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Carbohydrate quality and human health: a series of systematic reviews and meta-analyses
Abstract
Background:
Previous systematic reviews and meta-analyses explaining the relationship between carbohydrate quality and health have usually examined a single marker and a limited number of clinical outcomes. We aimed to more precisely quantify the predictive potential of several markers, to determine which markers are most useful, and to establish an evidence base for quantitative recommendations for intakes of dietary fibre.
Methods:
We did a series of systematic reviews and meta-analyses of prospective studies published from database inception to April 30, 2017, and randomised controlled trials published from database inception to Feb 28, 2018, which reported on indicators of carbohydrate quality and non-communicable disease incidence, mortality, and risk factors. Studies were identified by searches in PubMed, Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials, and by hand searching of previous publications. We excluded prospective studies and trials reporting on participants with a chronic disease, and weight loss trials or trials involving supplements. Searches, data extraction, and bias assessment were duplicated independently. Robustness of pooled estimates from random-effects models was considered with sensitivity analyses, meta-regression, dose-response testing, and subgroup analyses. The GRADE approach was used to assess quality of evidence.
Findings:
Just under 135 million person-years of data from 185 prospective studies and 58 clinical trials with 4635 adult participants were included in the analyses. Observational data suggest a 15-30% decrease in all-cause and cardiovascular related mortality, and incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer when comparing the highest dietary fibre consumers with the lowest consumers Clinical trials show significantly lower bodyweight, systolic blood pressure, and total cholesterol when comparing higher with lower intakes of dietary fibre. Risk reduction associated with a range of critical outcomes was greatest when daily intake of dietary fibre was between 25 g and 29 g. Dose-response curves suggested that higher intakes of dietary fibre could confer even greater benefit to protect against cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer. Similar findings for whole grain intake were observed. Smaller or no risk reductions were found with the observational data when comparing the effects of diets characterised by low rather than higher glycaemic index or load. The certainty of evidence for relationships between carbohydrate quality and critical outcomes was graded as moderate for dietary fibre, low to moderate for whole grains, and low to very low for dietary glycaemic index and glycaemic load. Data relating to other dietary exposures are scarce.
Interpretation:
Findings from prospective studies and clinical trials associated with relatively high intakes of dietary fibre and whole grains were complementary, and striking dose-response evidence indicates that the relationships to several non-communicable diseases could be causal. Implementation of recommendations to increase dietary fibre intake and to replace refined grains with whole grains is expected to benefit human health. A major strength of the study was the ability to examine key indicators of carbohydrate quality in relation to a range of non-communicable disease outcomes from cohort studies and randomised trials in a single study. Our findings are limited to risk reduction in the population at large rather than those with chronic disease.
Funding:
Health Research Council of New Zealand, WHO, Riddet Centre of Research Excellence, Healthier Lives National Science Challenge, University of Otago, and the Otago Southland Diabetes Research Trust.
... Dietary fibre varies in their physicochemical properties, such as hydrophilicity, solubility, viscosity, and fermentability, which leads to various physiological effects. Since the viscous ones reduce the absorption of glucose and lipids in the intestinal tract [7,8], dietary fibre potentially contributes to the prevention of obesity, diabetes, and cardiovascular diseases (CVDs), which bear strong etiological links to metabolic disorders [9,10]. In addition, some etiological studies have shown that a lower intake of dietary fibre correlates with metabolic disorders such as obesity and diabetes [9], which are risk factors for CVDs. ...
... Since the viscous ones reduce the absorption of glucose and lipids in the intestinal tract [7,8], dietary fibre potentially contributes to the prevention of obesity, diabetes, and cardiovascular diseases (CVDs), which bear strong etiological links to metabolic disorders [9,10]. In addition, some etiological studies have shown that a lower intake of dietary fibre correlates with metabolic disorders such as obesity and diabetes [9], which are risk factors for CVDs. Given that the intake of dietary fibre is on the decline globally and is not at optimal levels (28-35 g/day for adults is recommended) [9,10], a lower intake of dietary fibre could serve as a breeding ground for liver steatosis. ...
... In addition, some etiological studies have shown that a lower intake of dietary fibre correlates with metabolic disorders such as obesity and diabetes [9], which are risk factors for CVDs. Given that the intake of dietary fibre is on the decline globally and is not at optimal levels (28-35 g/day for adults is recommended) [9,10], a lower intake of dietary fibre could serve as a breeding ground for liver steatosis. ...
This study investigated whether a standard calorie diet that is high in glucose and deficient in dietary fibre (described as HGD [high glucose diet]) induces hepatic fat accumulation in mice. We evaluated hepatic steatosis at 7 days and 14 days after the commencement of the HGD. Hepatic triglycerides and areas of oil droplets increased in the HGD group both at day 7 and day 14, whereas weight gain, weight of epididymal fat, and plasma levels of triglycerides were unaffected by HGD consumption. A microarray analysis of the livers revealed that the expression of lipogenesis-related genes was the most affected by HGD consumption. Furthermore, HGD consumption induced the expression of hepatic proteins of fatty acid synthetase, acetyl-CoA carboxylase alpha, and stearoyl-CoA desaturase 1, which are known to be involved in the synthesis of triglyceride. These results indicate that HGD consumption causes fat accumulation in the liver, with an increase in enzymes that are involved in de novo lipogenesis without an accompanying weight or obesity phenotype. Our new findings suggest that HGD consumption could serve as a breeding ground for liver steatosis.
... This study assessed the extent to which differences in adiposity and odds of metabolic syndrome in Pacific versus NZ European women could be explained by dietary fibre intakes. Our study showed that fibre intake is associated with lower adiposity (i.e., weight, BMI, WC, VAT%, and BF%) and metabolic syndrome, as has been demonstrated previously [27,28]. Our study also showed that fibre intakes were low across the whole group of women, for example, 89% of Pacific and 65% of NZ European women did not meet the recommendations (≥25 g/day [9]), and the main sources of fibre intake were discretionary foods for Pacific women suggesting lower overall diet quality. ...
... The association between higher fibre intake and lower risk of nutrition-related NCDs and their metabolic risk factors is well established [5,28]. These benefits have been attributed to the physiochemical and functional properties of dietary fibre [29] and more recently associated with gut microbiota composition and function [30][31][32]. ...
Background/Objectives: To assess associations between dietary fibre intake, adiposity, and odds of metabolic syndrome in Pacific and New Zealand European women. Methods: Pacific (n = 126) and New Zealand European (NZ European; n = 161) women (18–45 years) were recruited based on normal (18–24.9 kg/m²) and obese (≥30 kg/m²) BMIs. Body fat percentage (BF%), measured using whole body DXA, was subsequently used to stratify participants into low (<35%) or high (≥35%) BF% groups. Habitual dietary intake was calculated using the National Cancer Institute (NCI) method, involving a five-day food record and semi-quantitative food frequency questionnaire. Fasting blood was analysed for glucose and lipid profile. Metabolic syndrome was assessed with a harmonized definition. Results: NZ European women in both the low- and high-BF% groups were older, less socioeconomically deprived, and consumed more dietary fibre (low-BF%: median 23.7 g/day [25–75-percentile, 20.1, 29.9]; high-BF%: 20.9 [19.4, 24.9]) than Pacific women (18.8 [15.6, 22.1]; and 17.8 [15.0, 20.8]; both p < 0.001). The main source of fibre was discretionary fast foods for Pacific women and whole grain breads and cereals for NZ European women. A regression analysis controlling for age, socioeconomic deprivation, ethnicity, energy intake, protein, fat, and total carbohydrate intake showed an inverse association between higher fibre intake and BF% (β= −0.47, 95% CI = −0.62, −0.31, p < 0.001), and odds of metabolic syndrome (OR = 0.91, 95% CI = 0.84, 0.98, p = 0.010) among both Pacific and NZ European women (results shown for both groups combined). Conclusions: Low dietary fibre intake was associated with increased metabolic disease risk. Pacific women had lower fibre intakes than NZ European women.
... Similarly, a systematic review of the local food environment and diet revealed that households that reported easy access to supermarkets consumed more portions of fruits and vegetables than those with poorer access [27]. Similar studies documented an association between perceived food access and consumption of fruits and vegetables [42,54]. ...
... Traditional food staples such as maize, cassava and yams remain rich sources of essential micronutrients, are low in glycaemic index, high in dietary fibre and protective against gastrointestinal cancers [62]. Evidence from a systematic review and meta-analysis indicated that a higher dietary fibre intake was associated with a 15-30% reduction in mortality from cardiovascular diseases (CVD), and a reduced incidence of NCDs and colorectal cancers [54]. These traditional staples are also low in saturated fat, sugar and salt, reducing the risk of cardiovascular diseases [63,64]. ...
Background
Rapid urbanisation without concomitant infrastructure development has led to the creation of urban slums throughout sub-Saharan Africa. People living in urban slums are particularly vulnerable to food insecurity due to the lack of physical and economic accessibility to food. Hence, it is important to explore how vulnerable groups living in slums interact with the food environment. This study assessed the relationships between food insecurity, including restrictive coping strategies, food purchasing patterns and perceptions about the food environment among dwellers of selected urban slums in Ibadan, Nigeria.
Methods
This community-based cross-sectional study was conducted with people responsible for food procurement from 590 randomly selected households in two urban slums in Ibadan. Food insecurity and restrictive coping strategies were assessed using the Household Food Insecurity Access Scale and the Coping Strategy Index, respectively. We examined purchasing patterns of participants by assessing the procurement of household foodstuffs in different categories, as well as by vendor type. Participants’ perceptions of the food environment were derived through a five-item composite score measuring food availability, affordability and quality. Chi-square tests and logistic regression models analysed associations between food insecurity, purchasing patterns and perceptions of the food environment.
Results
The prevalence of food insecurity in the sample was 88%, with 40.2% of the households experiencing severe food insecurity. Nearly a third (32.5%) of the households used restrictive coping strategies such as limiting the size of food portions at mealtimes, while 28.8% reduced the frequency of their daily meals. Participants purchased food multiple times a week, primarily from formal and informal food markets rather than from wholesalers and supermarkets. Only a few households grew food or had livestock (3.2%). Food insecure households had a lower perceived access to the food environment, with an approximate 10% increase in access score per one-unit decrease in food insecurity (AOR = 0.90, 95% CI: 0.84, 0.96). The most procured foods among all households were fish (72.5%), bread (60.3%), rice (56.3%), yam and cassava flours (50.2%). Food-secure households procured fruit, dairy and vegetable proteins more frequently.
Conclusion
Food insecurity remains a serious public health challenge in the urban slums of Ibadan. Perceptions of greater access to the food environment was associated with increasing food security. Interventions should focus on creating more robust social and financial protections, with efforts to improve livelihoods to ensure food security among urban slum-dwellers.
... Diets high in fiber, increase SCFA acid-producing bacteria, protect against pathogenic bacteria, lower blood pressure, reduce cardiac fibrosis and hypertrophy, and improve insulin sensitivity [334][335][336][337]. In addition, while intestinal SCFA decreased in the elderly, specific butyrate-producing bacteria have been detected in centenarians [338,339]. ...
Aging is a key risk factor for numerous diseases, including cardiac diseases. High energy demands of the heart require precise cellular energy sensing to prevent metabolic stress. AMPK and sirtuins are key intracellular metabolic sensors regulating numerous cell functions, like mitochondrial function and biogenesis, autophagy, and redox balance. However, their function is impaired during the aging process leading to mitochondrial dysfunction, oxidative stress, and inflammation culminating in cardiovascular diseases. The underlying molecular mechanisms leading to dysfunction of metabolic sensing in the aging heart are complex and comprise both intracellular and systemic age-related alterations. In this study, we overview the current knowledge on the impact of aging on cardiac metabolic sensing, with a focus on AMPK and sirtuins, while mTOR pathway was only marginally considered. A particular focus was given to systemic factors, e.g., inflammation, vascular diseases, and microbiome.
... 36-39 on the other hand, an excessive intake of simple sugars can induce the impairment of glucose metabolism, hyperinsulinemia, obesity, and T2d. [39][40][41][42] In addition, the lower intake of fish could explain the insufficiency of PUFA, in particular omega 3 fatty acids, that could increase a pro-inflammatory status. 43 Finally, the increased intake of sodium intake has been associated with hyper- The strength of this study is the use of the weighted 7-day food records that represent the gold standard for the assessment of eating habits at an individual level. ...
... 114 In addition to the above studies, several other studies have shown that dietary fiber has a positive effect on health and glycemic control in patients with diabetes. 115 These findings suggest that dietary fiber supplementation is a simple but effective way to improve glycemic control in T1DM patients. Therefore, it is recommended that T1DM patients moderately increase dietary fiber intake in their daily diets and choose foods rich in soluble fiber, such as oats, beans and apples. ...
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by destruction of pancreatic β-cells, leading to insulin deficiency and hyperglycemia, and its incidence is increasing year by year. The pathogenesis of T1DM is complex, mainly including genetic and environmental factors. Intestinal flora is the largest microbial community in the human body and plays a very important role in human health and disease. In recent years, more and more studies have shown that intestinal flora and its metabolites, as an environmental factor, regulate the development of T1DM through various mechanisms such as altering the intestinal mucosal barrier, influencing insulin secretion and body immune regulation. Intestinal flora transplantation, probiotic supplementation, and other approaches to modulate the intestinal flora appear to be potential therapeutic approaches for T1DM. This article reviews the dysbiosis of the intestinal flora in T1DM, the potential mechanisms by which the intestinal flora affects T1DM, as well as discusses potential approaches to treating T1DM by intervening in the intestinal flora.
... The quality of carbohydrates, classified as simple or complex carbohydrates or high-glycemic index (GI) and low-GI foods, plays a crucial role in cardiovascular health [39]. High-quality carbohydrates, such as whole grains, legumes, and fruits, are associated with lower CVD risk [40][41][42][43]. Diets rich in high-GI carbohydrates have been associated with increased heart disease risk, whereas low-GI diets appear protective [44]. ...
Background: Cardiovascular diseases (CVDs) are a major public health concern. The impact of dietary components on CVD risk has been recognized, but their interactions require further investigation. This study aimed to examine the associations between major nutrient intake and CVD risk and to assess potential causal relationships via Mendelian randomization. Methods: We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES) 2017–2020, with a sample size of 5464 adult participants. Nutrient intake was derived from two 24 h dietary recalls. Associations between four principal nutrients and CVD risk were evaluated via Mendelian randomization analysis. Additionally, weighted multivariable logistic regression analyses were performed to adjust for potential confounders, including age, sex, BMI, and other lifestyle factors. Results: An observational analysis revealed that increased log-transformed dietary fat intake was associated with reduced heart failure risk (OR = 0.722, 95% CI: 0.549–0.954). Log-transformed protein intake was protective against heart failure (OR = 0.645, 95% CI: 0.471–0.889), coronary artery disease (OR = 0.684, 95% CI: 0.504–0.931), and stroke (OR = 0.747, 95% CI: 0.568–0.988). IVW-MR analyses confirmed causal relationships between relative fat intake and heart failure risk (OR = 0.766, 95% CI: 0.598–0.982, p = 0.035) and between protein intake and stroke risk (OR = 0.993, 95% CI: 0.988–0.998, p = 0.010). MR analysis also revealed causal relationships between relative fat intake and coronary artery disease risk and between relative protein intake and hypertension risk. Conclusions: Both the observational and Mendelian randomization studies indicated that dietary fat is inversely associated with heart failure risk and that protein intake is correlated with reduced stroke risk. Future studies should investigate the optimal balance of macronutrients for CVD prevention, explore potential mechanisms underlying these associations, and consider long-term dietary interventions to validate these findings.
... Dietary fiber (DF) is a type of carbohydrate that is not/ only partially hydrolyzed or absorbed in the human small intestine [9]. DF has been shown to provide various benefits in disease prevention among healthy individuals, including, among other benefits, reduced risk of mortality, type-2 diabetes, and cardiovascular disease [10][11][12][13]. A recent narrative review suggested considerable benefits from DF in critically ill patients, attributed to its functions in maintaining gut barrier integrity, modulating immune responses, supporting the gut microbiome, and contributing to systemic anti-inflammatory responses [9]. ...
Background
Evidence on the benefits of fiber-supplemented enteral nutrition (EN) in critically ill patients is inconsistent, and critical care nutrition guidelines lack recommendations based on high-quality evidence. This systematic review and meta-analysis (SRMA) aims to provide a current synthesis of the literature on this topic.
Methods
For this SRMA of randomized controlled trials (RCT), electronic databases (MEDLINE, EMBASE, CENTRAL) were searched systematically from inception to January 2024 and updated in June 2024. Trials investigating clinical effects of fiber-supplemented EN versus placebo or usual care in adult critically ill patients were selected. Two independent reviewers extracted data and assessed the risk of bias of the included studies. Random-effect meta-analysis and trial sequential analysis (TSA) were conducted. The primary outcome was overall mortality, and one of the secondary outcomes was diarrhea incidence. Subgroup analyses were also performed for both outcomes.
Results
Twenty studies with 1405 critically ill patients were included. In conventional meta-analysis, fiber-supplemented EN was associated with a significant reduction of overall mortality (RR 0.66, 95% CI 0.47, 0.92, p = 0.01, I ² = 0%; 12 studies) and diarrhea incidence (RR 0.70, 95% CI 0.51, 0.96, p = 0.03, I ² = 51%; 11 studies). However, both outcomes were assessed to have very serious risk of bias, and, according to TSA, a type-1 error cannot be ruled out. No subgroup differences were found for the primary outcome.
Conclusion
Very low-certainty evidence suggests that fiber-supplemented EN has clinical benefits. High-quality multicenter RCTs with large sample sizes are needed to substantiate any firm recommendation for its routine use in this group of patients.
PROSPERO registration number: CRD42023492829.
... It reaches the large intestine and is fermented by resident gut bacteria to produce microbial metabolites such as short-chain fatty acids (SCFA) including acetate, propionate, and butyrate. Observational data suggest that higher intakes of dietary fibre, when compared with the lowest consumers, are associated with reduced risk of non-communicable diseases, including colorectal cancer, diabetes, and cardiovascular disease (2) . The proposed mechanisms through which dietary fibres exert their beneficial health effects include modulation of the gut microbiota and synthesis of microbial metabolites, primarily SCFAs. ...
The gut microbiome is impacted by certain types of dietary fibre. However, the type, duration, and dose needed to elicit gut microbial changes, and whether these changes also influence microbial metabolites, remains unclear. This study investigated the effects of supplementing healthy participants with two types of non-digestible carbohydrates (resistant starch (RS) and polydextrose (PD)), on the stool microbiota and microbial metabolite concentrations in plasma, stool, and urine, as secondary outcomes in the Dietary Intervention Stem Cells and Colorectal Cancer (DISC) Study.
The DISC Study was a double-blind, randomised controlled trial that supplemented healthy participants with RS and/or PD or placebo for 50 days in a 2*2 factorial design. DNA was extracted from stool samples collected pre- and post-intervention, and V4 16S rRNA gene sequencing was used to profile the gut microbiota. Metabolite concentrations were measured in stool, plasma, and urine by high-performance liquid chromatography.
A total of 58 participants with paired samples available were included. After 50 days, no effects of RS or PD were detected on composition of the gut microbiota diversity (alpha- and beta-diversity), on genus relative abundance, or on metabolite concentrations. However, Drichlet’s multinomial mixture clustering-based approach suggests that some participants changed microbial enterotype post-intervention.
The gut microbiome and faecal, plasma, and urinary microbial metabolites were stable in response to a 50-day fibre intervention in middle aged adults. Larger and longer studies, including those which explore the effects of specific fibre sub-types, may be required to determine the relationships between fibre intake, the gut microbiome, and host-health.
... The benefits of fiber consumption in reducing CVD risk align with the findings of Zhang et al. 's study conducted on a population of 14,947 individuals [46]. It appears that an education-based approach promoting a healthy diet, emphasizing increased consumption of whole grains, fruits, and fiber-rich vegetables, could be beneficial in preventing CVD [47][48][49]. ...
Background
Globorisk is one of the prediction tools for 10-year risk assessment of cardiovascular disease, featuring an office-based (non-laboratory-based) version. This version does not require laboratory tests for determining the CVD risk. The present study aims to determine the 10-year CVD risk using the office-based Globorisk model and factors associated with the 10-year CVD risk.
Methods
In this study, baseline data from 6810 individuals participating in the Fasa cohort study, with no history of CVD or stroke, were utilized. The risk equation of the office-based Globorisk model incorporates age, sex, systolic blood pressure (SBP), body mass index (BMI), and smoking status. The Globorisk model categorizes the risk into three groups: low risk (< 10%), moderate risk (10% to < 20%), and high risk (≥ 20%). To identify factors associated with the 10-year CVD risk, the predicted risk was categorized into two groups: <10% and ≥ 10%. Multivariable logistic regression analysis was employed to determine factors associated with an increased CVD risk.
Results
According to the 10-year CVD risk categorization, 78.3%, 16.4%, and 5.3% of men were in the low, moderate, and high risk groups, respectively, while 85.8%, 10.0%, and 4.2%, of women were in the respective risk groups. Multivariable logistic regression results indicated that in men, the 10-year CVD risk decreases with being an opium user, and increases with being illiterate, having abdominal obesity, and low or moderate physical activity compared to high physical activity. In women, being married, and higher fiber consumption decrease the 10-year CVD risk, while being illiterate, low or moderate physical activity compared to high physical activity, having abdominal obesity, opium use, and being in wealth quintiles 1 to 4 compared to quintile 5 increase the risk.
Conclusions
Considering the factors associated with increased CVD risk, there is a need to enhance awareness and modify lifestyle to mitigate and reduce the risk of CVD. Additionally, early identification of individuals at moderate to high risk is essential for preventing disease progression. The use of the office-based Globorisk model can be beneficial in settings where resources are limited for determining the 10-year CVD risk.
... Globally, the current fiber recommendations are largely based on daily energy intake (3-4 g/MJ per day), which is extrapolated to 25-32 g/day for adult women and 30-35 g/day for adult men (Stephen et al., 2017). It is agreed that a fiber intake of 25 g/day would be adequate for maintaining normal laxation in adults, and a higher intake of fiber would be necessary to reduce the risk of NCDs (O'Keefe, 2019; Reynolds et al., 2019). For example, an increment of 7 g/day total fiber intake was associated with significant risk reduction by 9% for coronary heart and cardiovascular diseases (Threapleton et al., 2013). ...
Clarification is required when the term “carbohydrate” is used interchangeably with “saccharide” and “glycan.” Carbohydrate classification based on human digestive enzyme activities brings clarity to the energy supply function of digestible sugars and starch. However, categorizing structurally diverse non‐digestible carbohydrates (NDCs) to make dietary intake recommendations for health promotion remains elusive. In this review, we present a summary of the strengths and weaknesses of the traditional dichotomic classifications of carbohydrates, which were introduced by food chemists, nutritionists, and microbiologists. In parallel, we discuss the current consensus on commonly used terms for NDCs such as “dietary fiber,” “prebiotics,” and “fermentable glycans” and highlight their inherent differences from the perspectives of gut microbiome. Moreover, we provide a historical perspective on the development of novel concepts such as microbiota‐accessible carbohydrates, microbiota‐directed fiber, targeted prebiotics, and glycobiome. Crucially, these novel concepts proposed by multidisciplinary scholars help to distinguish the interactions between diverse NDCs and the gut microbiome. In summary, the term NDCs created based on the inability of human digestive enzymes fails to denote their interactions with gut microbiome. Considering that the gut microbiome possesses sophisticated enzyme systems to harvest diverse NDCs, the subclassification of NDCs should be realigned to their metabolism by various gut microbes, particularly health‐promoting microbes. Such rigorous categorizations facilitate the development of microbiome‐targeted therapeutic strategies by incorporating specific types of NDCs.
... This variation may be influenced by the intake of specific food sources, such as tomatoes and other vegetables (Table S2), which contain bioactive compounds like lycopene and tomatine that can effectively reduce markers of oxidative stress [39][40][41]. These findings suggest that while the intake of high-quality carbohydrates is associated with a reduction in cardiovascular risk factors, weight loss, and a decreased risk of diabetes and cardiovascular diseases [42,43]-resulting in a lower all-cause mortality risk among participants consuming higher amounts of HQCs [44]-excessive intake can also adversely affect health and aging. Overconsumption of simple sugars may lead to various health issues [45]. ...
Background: There is growing evidence that diet and aging are associated; however, few studies have examined the relationship between macronutrient subtypes and phenotypic age acceleration, and the extent to which BMI (body mass index) mediates this association is unclear. Methods: This study included 6911 individuals who were 20 years or older and had participated in the National Health and Nutrition Examination Survey. Daily macronutrient intakes were calculated and classified by the quartile of their subtypes. PhenoAgeAccel was calculated as an aging index using nine chemistry biomarkers. Multivariable linear regression and isocaloric substitution effects were used to evaluate the association of macronutrients with PhenoAgeAccel. Mediation analyses were used to examine the mediation role of BMI in the association. Results: After adjusting for the potential covariates, the consumption of high-quality carbohydrates (β = −1.01, 95% CI: −1.91, −0.12), total protein (β = −2.00, 95% CI: −3.16, −0.84), and plant protein (β = −1.65, 95% CI: −2.52, −0.78) was negatively correlated with PhenoAgeAccel; the consumption of SFAs (β = 1.77, 95% CI: 0.72, 2.81) was positively correlated with PhenoAgeAccel. For every serving of low-quality carbohydrates/animal protein and other calories replaced by one serving of high-quality carbohydrates/plant protein, PhenoAgeAccel would be reduced by about 25 percent. The ratio between BMI-mediated high-quality carbohydrates and PhenoAgeAccel accounted for 19.76% of the total effect, while the ratio between BMI-mediated total fat and PhenoAgeAccel accounted for 30.78% of the total effect. Conclusions: Different macronutrient consumption subtypes are related to PhenoAgeAccel, which is partially mediated by BMI, depending on the quality of macronutrients. Replacing low-quality macronutrients with high-quality macronutrients might slow aging.
... The benefits of consuming a sustainable diet for cardiovascular health occur mainly through the replacement of saturated fats with unsaturated fats and increased dietary fiber intake, both mechanisms leading to a reduction in the absorption of LDL-c and glucose [13,14], recognized risk factors for CVD [15,16]. In addition to improving lipid profiles, regular fiber consumption may promote weight loss and reduce visceral adiposity due to the satiety effect [17,18]. ...
Background
The EAT-Lancet diet is a diet aimed at promoting population and planetary health from the perspective of sustainable diets in terms of environmental and health aspects. This study aimed to assess the association between adherence to the EAT-Lancet diet and cardiometabolic risk factors among adults and elderly individuals in a capital city in the northeastern region of Brazil.
Methods
This is an analytical cross-sectional observational study from a population-based sample conducted between 2019 and 2020, involving 398 non-institutionalized adults and elderly people, of both sexes from “Brazilian Usual Consumption Assessment” study (Brazuca-Natal). There was a 38% response rate due to the suspension of data collection due to the covid-19 pandemic, but According to the comparative analysis of socioeconomic and demographic variables between the surveyed and non-surveyed sectors, losses were found to be random (p = 0.135, Little’s MCAR test). Socioeconomic and lifestyle data, anthropometric measurements, and dietary consumption were collected. We used the Planetary Health Diet Index (PHDI) and the Cardiovascular Health Diet Index (CHDI) for cardiovascular health to assess adherence to the diet’s sustainability. The evaluated cardiometabolic parameters included fasting blood glucose, triglycerides, total cholesterol, HDL-C, LDL-C, and systolic and diastolic blood pressure measurements. We also assessed the presence of type 2 diabetes mellitus, arterial hypertension, and dyslipidemia. For the data analyses, sample weights and the effect of the study design were taken into account. Pearson’s chi-square test was used to evaluate the statistical significance of frequencies. Multiple linear regression models assessed the associations between PHDI and CHDI and its components and the cardiometabolic parameters.
Results
The mean PHDI was 29.4 (95% CI 28.04:30.81), on a total score ranging from 0 to 150 points and the mean CHDI was 32.63 (95% CI 31.50:33.78), on a total score ranging from 0 to 110 points. PHDI showed a significant positive association with the final CHDI score and components of fruits, vegetables, and legumes, and a negative association with Ultra-processed Food (UPF) (p < 0.05). Notably, among the most consumed UPF, the following stand out: “packaged snacks, shoestring potatoes, and crackers” (16.94%), followed by margarine (14.14%). The PHDI exhibited a significant association with diabetes and dyslipidemia, as well as with systolic blood pressure, total cholesterol, and LDL-C.
Conclusions
The results suggest that adopting the EAT-Lancet diet is associated with the improvement of key cardiovascular health indicators.
... High-fibre diets are associated with lower weight gain. 8 Dietary fibres are largely indigestible in the small intestine and reach the colon where gut bacteria ferment them to produce short-chain fatty acids (SCFAs): acetate, propionate, and butyrate. 9 In humans, SCFAs are natural ligands for free fatty acid receptor (FFARs) activation in the gastrointestinal tract and appear to play a role in modulating appetite and energy balance. ...
Background
Obesity drives metabolic disease development. Preventing weight gain during early adulthood could mitigate later-life chronic disease risk. Increased dietary fibre intake, leading to enhanced colonic microbial fermentation and short-chain fatty acid (SCFA) production, is associated with lower body weight. Despite national food policy recommendations to consume 30 g of dietary fibre daily, only 9% of adults achieve this target. Inulin-propionate ester (IPE) selectively increases the production of the SCFA propionate in the colon. In previous studies, IPE has prevented weight gain in middle-aged adults over 6 months, compared with the inulin control. IPE is a novel food ingredient that can be added to various commonly consumed foods with a potential health benefit. This 12-month study aimed to determine whether using IPE to increase colonic propionate prevents further weight gain in overweight younger adults.
Methods
This multi-centre randomised-controlled, double-blind trial was conducted in London and Glasgow, UK. Recruited participants were individuals at risk of weight gain, aged between 20 and 40 years and had an overweight body mass index. Sealed Envelope Software was used to randomise participants to consume 10 g of IPE or inulin (control), once per day for 12 months. The primary outcome was the weight gained from baseline to 12 months, analysed by an ‘Intention to Treat’ strategy. The safety profile and tolerability of IPE were monitored through adverse events and compliance. This study is registered with the International Standard Randomised Controlled Trials (ISRCT) Database (ISRCT number: 16299902).
Findings
Participants (n = 135 per study arm) were recruited from July 2019 to October 2021. At 12 months, there was no significant difference in baseline-adjusted mean weight gain for IPE compared with control (1.02 kg, 95% CI: −0.37 to 2.41; p = 0.15; n = 226). Neither the IPE (+1.22 kg) nor the control arm (+0.07 kg) unadjusted mean gains in body weight reached the expected 2 kg threshold. In the IPE arm, fat-free mass was greater by 1.07 kg (95% CI: 0.21–1.93), and blood glucose elevated by 0.11 mmol/L (95% CI: 0.01–0.21). Compliance, determined by intake of ≥50% sachets, was reached by 63% of IPE participants. There were no unexpected adverse events or safety concerns.
Interpretation
Our study indicates that at 12 months, IPE did not differentially affect weight gain, compared with the inulin control, in adults between 20 and 40 years of age, at risk of obesity.
Funding
NIHR EME Programme (15/185/16).
... Our findings that low dietary fiber intake is a major contributor to the global CVD burden align with prior evidence. Prospective studies and meta-analyses consistently demonstrate that higher fiber consumption lowers CVD incidence and mortality [16][17][18]. Each 7-10 gram per day increment in fiber intake reduces CVD events and coronary death by 10-20% [16,17]. ...
Objectives
This study aimed to quantify the global cardiovascular disease (CVD) burden attributable to diet low in fiber among adults aged 60 years and older using data from the Global Burden of Disease (GBD) Study 2019.
Methods
We extracted data on CVD mortality, disability-adjusted life-years (DALYs), and risk-factor exposures from the GBD 2019 study for people aged 60 and older. Age-period-cohort models were used to estimate the overall annual percentage change in mortality and DALY rate (net drift, % per year), mortality and DALY rate for each age group from 1990 to 2019 (local drift, % per year), longitudinal age-specific rate corrected for period bias (age effect), and mortality and Daly rate for each age group from 1990 to 2019 (local drift, % per year). And period/cohort relative risk (period/cohort effect).
Results
From 1990 to 2019, global age-standardized cardiovascular disease (CVD) mortality rates attributable to low dietary fiber intake decreased by 2.37% per year, while disability-adjusted life years (DALYs) fell by 2.48% annually. Decreases were observed across all sociodemographic index regions, with fastest declines in high and high-middle SDI areas. CVD mortality and DALY rates attributable to low fiber increased exponentially with age, peaking at 85–89 years, and were higher in men than women. Regarding period effects, mortality and DALY rates declined since 2000, reaching nadirs in 2015–2019. For birth cohort patterns, risks attributable to low fiber intake peaked among early 1900s births and subsequently fell, with more pronounced reductions over time in women.
Conclusions
Low dietary fiber intake is a leading contributor to the global cardiovascular disease burden, accounting for substantial mortality and disability specifically among older adults over recent decades.
... Dietary fibers are an important component of the diet associated with lowering risks of chronic diseases and promoting bowel health [1,2]. The health a major fuel source for colonocytes [5,6]. ...
BACKGROUND: Butyrate is a health promoting short-chain fatty acid (SCFA) metabolite of fiber fermentation in the gut. Supplementing directly with a butyrate generator may be a dietary alternative with health benefits. OBJECTIVE: To evaluate the effect of tributyrin, a butyrate generator, on tolerability, gut microbiome composition, gut permeability, inflammation and metabolic markers in healthy adults at two dose levels. METHODS: Healthy adults (n = 29) were randomized to this single-blinded, two-arm, 28-day parallel design pilot study. Participants ingested one or two placebo capsules for 7 days followed by one or two (200 or 400 mg, respectively) ButyraGen® capsules, a novel tributyrin complex, daily for 21 days. Tolerability was assessed weekly by questionnaire. Blood and stool were collected at baseline and weekly for metabolic and inflammation markers, gut microbiome composition and SCFA concentrations, respectively. Urine was collected at baseline and end of the study for permeability assays. RESULTS: Twenty-four participants (n = 24, 25±8 years; 24.0±2.8 kg/m2; 66% male) completed the study. ButyraGen® was well-tolerated, with less than 10% (n = 2) reporting gastrointestinal-related discomfort. Fecal acetic (p = 0.03) and propionic (p = 0.03) acids decreased after supplementation (p = 0.03 and p = 0.03, respectively, n = 24) compared to baseline, and triglycerides increased (p = 0.02, 400 mg only, n = 11). Trends in decreased hs-CRP after 200 mg (p = 0.08) and 400 mg (p = 0.07) supplementation and decreased glucose (p = 0.10) after 200 mg supplementation was observed. No other changes in endpoints were observed. CONCLUSIONS: Tributyrin supplementation using ButyraGen® was safe and tolerable at the doses provided. Biological effects were observed suggesting butyrate generation and absorption in the small intestine followed by activity in the liver, though further investigation on mechanism of action is needed for confirmation.
... 41 Consume foods high in dietary fiber to reach a daily intake >25 g A meta-analysis revealed that high dietary fiber intake reduces total cholesterol compared with low fiber intake, with 25-29 g/day showing health benefits. 42 Dietary fiber, especially water-soluble fiber, reduces intestinal fat absorption and increases hepatic LDLR with lower VLDL secretion, thereby lowering blood cholesterol levels in animals. 43 The WHO recommends consuming at least 400 g of fruits and vegetables per day to increase dietary fiber intake. ...
... The magnitude of reduction we observed is similar to another meta-analysis that demonstrated a MD of À0.90 kg (95% CI À1.77, À0.02 kg) from interventional trials utilizing prebiotics in adults with BMI of !25 [11]. Surprisingly, the magnitude of body weight reduction in the present meta-analysis is even greater than other meta-analyses evaluating the effect of different sources of dietary fiber (MD: À0.37 kg; 95% CI: À0.63, À0.11 kg) [59], fiber-fortified food (MD: À0.31 kg; 95% CI: À0.59, À0.03 kg) [60], and dietary viscous fiber (MD: À0.33 kg; 95% CI: À0.51, À0.14 kg) [61]. The mechanisms underlying the greater weight management-related outcomes induced by prebiotic frutans could include their role as a selective substrate for beneficial gut microbiota and the metabolites they produce including SCFAs [9]. ...
Background: Excess body weight and adiposity can adversely affect metabolic health. Prebiotics such as inulin-type fructans (ITFs) from chicory root are known to modulate gut microbiota and may improve body weight regulation.
Objectives: This study aimed to assess evidence for chicory ITF supplementation to support weight management.
Methods: Eligible articles (initial search to 2021, updated to February 2023) were searched from EMBASE, MEDLINE (PubMed), and Cochrane Library. Data on primary (body weight) and secondary outcomes [body mass index (BMI), total fat mass, body fat percentage, and waist circumference] were extracted by 2 reviewers independently. Random-effects model using inverse-variance method was used. Subgroup analysis (health status and ITF type) and meta-regression (dose and duration) were evaluated.
Results: A total of 32 eligible studies were included. Chicory ITF significantly reduced body weight [mean difference (MD): -0.97 kg; 95% CI: 1.34, 0.59); n=1184] compared with placebo. ITF favored overall effects reduction in BMI (MD: -0.39 kg/m2; 95% CI: -0.57, -0.20; n=985), fat mass (MD: -0.37 kg; 95% CI: -0.61, -0.13; n=397), waist circumference (MD: -1.03 cm; 95% CI: -1.69, -0.37; n=604), and for intervention duration of >8 wk, body fat percentage (MD: -0.78%; 95% CI: -1.17, -0.39; n=488). Except for considerable heterogeneity in body weight (I2: 73%) and body fat percentage (I2: 75%), all other outcomes had negligible to moderate heterogeneity. Significant reduction in body weight, BMI, and waist circumference was evident irrespective of participants' health status. There was minimal evidence that dose, duration, or type of ITF influenced the magnitude of reductions in outcomes.
Conclusions: Chicory ITF supplementation may benefit weight management by reducing body weight, BMI, fat mass, waist circumference, and, to a certain extent, body fat percentage.
This trial was registered at PROSPERO as CRD42020184908.
Keywords: inulin, oligofructose, weight management, meta-analysis, meta-regression, systematic review
... Overall glycaemic index (GI) and dietary glycaemic load (GL) have been used as indicators of carbohydrate quality (1,2) . These metrics are based on the acute impact of digestible carbohydrates on blood glucose (3)(4)(5) . ...
Previous studies have found direct associations between glycaemic index (GI) and glycaemic load (GL) with chronic diseases. However, this evidence has not been consistent in relation to mortality, and most data regarding this association come from high-income and low-carbohydrate-intake populations. The aim of this study was to evaluate the association between the overall GI and dietary GL and all-cause mortality, CVD and breast cancer mortality in Mexico. Participants from the Mexican Teachers’ Cohort (MTC) study in 2006–2008 were followed for a median of 10 years. Overall GI and dietary GL were calculated from a validated FFQ. Deaths were identified by the cross-linkage of MTC participants with two national mortality registries. Cox proportional hazard models were used to estimate the impact of GI and GL on mortality. We identified 1198 deaths. Comparing the lowest and highest quintile, dietary GI and GL appeared to be marginally associated with all-cause mortality; GI, 1·12 (95 % CI: 0·93, 1·35); GL, 1·12 (95 % CI: 0·87, 1·44). Higher GI and GL were associated with increased risk of CVD mortality, GI, 1·30 (95 % CI: 0·82, 2·08); GL, 1·64 (95 % CI: 0·87, 3·07) and with greater risk of breast cancer mortality; GI, 2·13 (95 % CI: 1·12, 4·06); GL, 2·43 (95 % CI: 0·90, 6·59). It is necessary to continue the improvement of carbohydrate quality indicators to better guide consumer choices and to lead the Mexican population to limit excessive intake of low-quality carbohydrate foods.
... However, adherence to dietary fibre recommendations in the UK and globally is low (13)(14)(15)(16)(17) . Therefore, it is important to put these values into context and understand how individuals can adhere to these 30 g/d recommendations (18) . ...
The UK population is living longer; therefore, promoting healthy ageing via positive nutrition could have widespread public health implications. Moreover, dietary fibre intake is associated with health benefits; however, intake is below UK recommendations (30 g/d). Utilising national dietary survey data can provide up-to-date information on a large representative cohort of UK older adults, so that tailored solutions can be developed in the future. This study used cross-sectional data from the National Diet and Nutrition Survey (years 2008–2009 to 2018–2019) for older adults’ (n 1863; 65–96 years) dietary fibre intake (three-to-four-day food diaries), top ten dietary fibre-rich foods, associated factors (demographics, dietary/lifestyle habits) and various health outcomes (anthropometric, blood and urine). Mean dietary fibre intake was 18·3 g/d (range: 2·9–55·1 g/d); therefore, below the UK dietary recommendations, with compliance at 5·7 %. In addition, there were five significant associations (P < 0·05) related to lower dietary fibre intake such as increasing age group, without own natural teeth, impaired chewing ability, lower education leaving age and poor general health. Older adults’ key foods containing dietary fibre were mainly based on convenience such as baked beans, bread and potatoes. Positively, higher dietary fibre consumption was significantly associated (P = 0·007) with reduced diastolic blood pressure. In summary, the benefits of dietary fibre consumption were identified in terms of health outcomes and oral health were key modulators of intake. Future work should focus on a life course approach and the role of food reformulation to help increase dietary fibre intake.
The Cereus genus includes medicinal plants native to the Neotropical region. Although their colorful fruits are consumed in arid and semi-arid areas, these are underused industrially due to limited knowledge. This review presents recent studies on the chemical, physicochemical, and bioactive aspects of Cereus fruits, along with pharmacotherapeutic benefits and potential applications of peel, pulp, and seed compounds. Cereus fruits exhibit high nutritional value and richness in bioactive compounds. Their peel has the highest antioxidant concentration, mainly phenolics, flavonoids, and carotenoids. Their pulp offers significant dietary fiber and energy. Seed flour and oil are rich in minerals (K, P and Mg), and also contain oleic, linoleic, and palmitic acids. Most studies focus on Cereus jamacaru, indicating the need to explore other Cereus species for their varied compositions, in addition to innovative physicochemical analyses to uncover relevant compounds.
Purpose
To assess the effects of carbohydrate timing and type on body composition and physical fitness.
Methods
Forty-two healthy, trained male volunteers underwent a four-week intervention, randomly divided into three groups: (i) Sleep Low-No Carbohydrates (SL-NCHO): consuming all carbohydrate intake at regular intervals prior to evening training, (ii) Sleep High-Low Glycemic Index (SH-LGI), and (iii) Sleep High-High Glycemic Index (SH-HGI). In both SH-LGI and SH-HGI, carbohydrates were distributed throughout the day, both pre-(60% of total intake) and post-evening training (40% of total intake). The SH-LGI and SH-HGI groups diverged in evening carbohydrate quality, featuring LGI and HGI foods, respectively. All participants performed a standardized exercise program combining resistance exercise and high-intensity interval training. Body composition was assessed using skinfold measurements and bioelectrical impendence analysis. Physical fitness was assessed by measuring VO2max, Visual Reaction Time (VRT), Countermovement Jump (CMJ), and 1-repetition maximum (1RM) in hack squat, chest press, shoulder press, and lat-pulldown exercises.
Results
There was a significant time-effect on both body composition and physical fitness indices. Bodyfat percentage decreased by an average of 1.5% (p < 0.001), fat-mass by 1.4 kg (p < 0.001) and fat-free mass increased by 0.9 kg (p = 0.006). A time-effect was also observed in VO2max, CMJ, 1RM testing, and VRT (all p < 0.05). There were no significant differences among interventions.
Conclusions
A balanced dietary plan with sufficient nutrient and energy intake promotes body composition optimization and physical fitness, independently of carbohydrate type or timing. This study points towards implementing flexible nutrition interventions, emphasizing the potential of tailored dietary strategies to optimize health and physical fitness.
Trial registration number
The trial was registered at clinicaltrials.gov as NCT05464342.
Eurasian clinical practice guidelines for dietary management of cardiovascular diseases include actual healthy diet recommendations and modern dietary approaches for prevention and treatment of cardiovascular diseases. Nutritional assessment and interventions based on pathogenesis of atherosclerosis and cardiovascular diseases are presented.
Modern nutritional and dietary recommendations for patients with arterial hypertension, coronary heart disease, chronic heart failure, heart rhythm disorders, dyslipidemia and gout are summarized in present recommendations. Particular attention is paid to the dietary management of cardiovascular patients with obesity and/or diabetes mellitus. This guide would be interesting and intended to a wide range of readers, primarily cardiologists, dietitians and nutritionists, general practitioners, endocrinologists, and medical students.
Purpose
Carbohydrate intake has been linked to colorectal cancer (CRC) risk, with variations depending on the quantity and quality of carbohydrates consumed. This study aimed to investigate the association between carbohydrate quantity and quality, using the low-carbohydrate diet score (LCD) and carbohydrate quality index (CQI), and the risk of CRC in the Chinese population.
Methods
We conducted a case–control study in Guangzhou, China, with 2,799 CRC cases and an equal number of sex- and age-matched controls. Dietary data were collected using a validated food frequency questionnaire to derive the LCD and CQI, assessing the quantity and quality of carbohydrate intake separately. Odds ratios (OR) and 95% confidence interval (CI) for CRC risk were estimated using unconditional logistic regression models, and restricted cubic splines were used to explore potential non-linear relationships.
Results
The results demonstrated that higher adherence to the overall LCD score, plant-based LCD score, and CQI was associated with a lower risk of CRC. The adjusted ORs (95%CIs) for the highest quintile of intake in comparison with the lowest quintile were 0.76 (0.63, 0.91) for the overall LCD score, 0.61 (0.50, 0.74) for the plant-based LCD score, and 0.70 (0.58,0.84) for the CQI, respectively. However, the animal-based LCD did not show a significant association with CRC risk, with the adjusted OR (95%CI) for the highest quintile compared to the lowest being 0.98 (0.81, 1.18). Restricted cubic splines analysis showed non-linear associations of the overall LCD score, animal-based LCD score, and plant-based LCD score with CRC risk. In contrast, a linear relationship was observed between CQI and CRC risk (Pnonlinear = 0.594).
Conclusions
Our findings indicate that the overall LCD score, the plant-based LCD score, and the CQI were inversely associated with the risk of CRC.
Cardiovascular disease (CVD) and cardiometabolic risk (CMR) are highly prevalent globally. The interplay between CVD/CMR and COVID-19 morbidity and mortality has been intensely studied over the last three years and has yielded some important discoveries and warnings for public health. Despite many advances in cardiovascular medicine, CVD continues to be the global leading cause of death. Much of this disease burden results from high CMR imposed by behaviors centered around poor nutrition related to lifestyle choices and systemic constraints. Increased CVD/CMR contributed to the COVID-19 pandemic’s unprecedented wave of disability and death, and the current state of cardiovascular health been equated to a “Population Code Blue.” There is an urgent and unmet need to reorient our priorities towards health promotion and disease prevention. This manuscript will review how nutrition and lifestyle affect outcomes in COVID-19 and how some interventions and healthy lifestyle choices can markedly reduce disease burden, morbidity, and mortality.
Grain products are a fundamental element in ensuring food security for the population. In recent years, the demand for whole grain products has significantly increased. Whole grain products are highly nutritious due to their balanced content of amino acids and other macro- and microelements. The aim of this study is to investigate the chemical and amino acid composition of whole grain raw materials such as triticale grain of the «Dauren» variety, buckwheat grain of the «Dikul» variety, and lentil grains of the «Sakura» and «Shyrayly» varieties. The chemical research revealed that whole leguminous crops have a high protein content, which is approximately twice as high as that of whole grains, with protein content values of 28,75% and 24,67%, respectively. The analysis of the conducted studies showed that the amino acid composition of the proteins in whole grains and whole leguminous crops is characterized by a high content of essential amino acids. Leguminous crops have a higher content of arginine and lysine compared to whole grains. Whole leguminous crops have a higher protein content than whole grains, making them important for increasing the nutritional value of food products when mixed. Additionally, various processing methods and their effects on preserving nutritional properties were studied.
Background: Obesity, a prevalent and multifactorial disease, is linked to a range of metabolic abnormalities, including insulin resistance, dyslipidemia, and chronic inflammation. These imbalances not only contribute to cardiometabolic diseases but also play a significant role in cancer pathogenesis. The rising prevalence of obesity underscores the need to investigate dietary strategies for effective weight management for individuals with overweight or obesity and cancer. This European Society for the Study of Obesity (EASO) position statement aimed to summarize current evidence on the role of obesity in cancer and to provide insights on the major nutritional interventions, including Mediterranean Diet (MedDiet), ketogenic diet (KD), and intermittent fasting (IF), that should be adopted to manage individuals with overweight or obesity and cancer. Results: The MedDiet, characterized by high consumption of plant-based foods and moderate intake of olive oil, fish, and nuts, has been associated with a reduced cancer risk. The KD and the IF are emerging dietary interventions with potential benefits for weight loss and metabolic health. KD, by inducing ketosis, and IF, through periodic fasting cycles, may offer anticancer effects by modifying tumor metabolism and improving insulin sensitivity. Key messages: Despite the promising results, current evidence on these dietary approaches in cancer management in individuals with overweight or obesity is limited and inconsistent, with challenges including variability in adherence and the need for personalized dietary plans.
Epidemiological investigation confirmed that the intake of dietary fiber (DF) is closely related to human health, and the most important factor affecting the physiological function of DF, besides its physicochemical properties, is the gut microbiota. This paper mainly summarizes the interaction between DF and gut microbiota, including the influence of DF on the colonization of gut microbiota based on its different physicochemical properties, and the physiological role of gut microbiota in destroying the complex molecular structure of DF by encoding carbohydrate-active enzymes, thus producing small molecular products that affect the metabolism of the host. Taking cardiovascular disease (Atherosclerosis and hypertension), liver disease, and immune diseases as examples, it is confirmed that some DF, such as fructo-oligosaccharide, galactooligosaccharide, xylo-oligosaccharide, and inulin, have prebiotic-like physiological effects. These effects are dependent on the metabolites produced by the gut microbiota. Therefore, this paper further explores how DF affects the gut microbiota’s production of substances such as short-chain fatty acids, bile acids, and tryptophan metabolites, and provides a preliminary explanation of the mechanisms associated with their impact on host health. Finally, based on the structural properties of DF and the large heterogeneity in the composition of the population gut microbiota, it may be a future trend to utilize DF and the gut microbiota to correlate host health for precision nutrition by combining the information from population disease databases.
The gut, often referred to as the "second brain," has significant contributions in the maintaining of the good bacteria contribute enormous role such as digestion, produce essential vitamins, support the immune system, and protect against harmful bacteria. The beneficial flora including Akkermansia muciniphila, Adlercreutzia equolifasciens, Barnesiella, Christensenella minuta, and Oxalobacter formigenes, along with their derived bioactive metabolites emerged as a key player in maintaining host metabolic and immune health. Dietary choices such as blending of prebiotic, fermented, symbiotic, anti-inflammatory foods, and secondary metabolites from a wide variety of plants and fruits promotes the diversity, composition, and stability of beneficial intestinal microbes. The colourful plant foods rich in phytochemicals bioactive compounds such as carotenoids, flavonoids, polyphenols, alkaloids, anthocyanins, and capsaicin offer a wide array of unique properties such as analgesics, antioxidants, anti-inflammatory, antimicrobials effect and promoting the abundance of beneficial gut bacteria and their bioactive metabolites confer numerous health-promoting effects. Here, we present knowledge about most beneficial gut bacteria and their derived metabolites in terms of their sources and health benefits. Finally, we discuss best foods that skew towards promoting healthy intestinal microbes.
Dietary fibres constitute a heterogeneous class of nutrients that are key in the prevention of various chronic diseases. Most dietary fibres are fermented by the gut microbiome and may, thereby, modulate the gut microbial ecology and metabolism, impacting human health. Dietary fibres may influence the occurrence of specific bacterial taxa, with this effect varying between individuals. The effect of dietary fibres on microbial diversity is a matter of debate. Most intervention studies with dietary fibres in the context of obesity and related metabolic disorders reveal the need for an accurate assessment of the microbiome to better understand the variable response to dietary fibres. Epidemiological studies confirm that a high dietary fibre intake is strongly associated with a reduced occurrence of many types of cancer. However, there is a need to determine the impact of intervention with specific dietary fibres on cancer risk, therapy efficacy and toxicity, as well as in cancer cachexia. In this Review, we summarize the mechanisms by which the gut microbiome can mediate the physiological benefits of dietary fibres in the contexts of obesity, cardiometabolic diseases and cancer, their incidence being clearly linked to low dietary fibre intake.
Epidemiological studies show associations between the consumption of ultra-processed food (UPF) and numerous diseases. So far, however, there is no evidence of a causal relationship from randomised controlled trials. In addition, the individual UPFs differ considerably regarding their nutritional profiles and physiological effects. Differentiated analyses of epidemiological data indicate that the association of UPF consumption with adverse health effects is dominated by two food groups only (meat products, sugar-sweetened beverages). Other UPFs show no respective or even protective associations. The UPF concept therefore has no advantage compared to the established classification systems; this applies in particular with regard to the health assessment of foods with a high content of (saturated) fatty acids, salt, and sugar. The undifferentiated assessment of all UPFs, regardless of their nutritional profile, contradicts the current data and therefore lacks a scientific basis.
Whilst metabolic inflexibility and substrate constraint have been observed in heart failure for many years, their exact causal role remains controversial. In parallel, many of our fundamental assumptions about cardiac fuel use are now being challenged like never before. For example, the emergence of sodium glucose cotransporter 2 inhibitor (SGLT2i) therapy as one of the four “pillars” of heart failure therapy is causing a revisit of metabolism as a key mechanism and therapeutic target in heart failure. Improvements in the field of cardiac metabolomics will lead to a far more granular understanding of the mechanisms underpinning normal and abnormal human cardiac fuel use, an appreciation of drug action, and novel therapeutic strategies. Technological advances and expanding biorepositories offer exciting opportunities to elucidate the novel aspects of these metabolic mechanisms. Methodologic advances include comprehensive and accurate substrate quantitation such as metabolomics and stable-isotope fluxomics, improved access to arterio-venous blood samples across the heart to determine fuel consumption and energy conversion, high quality cardiac tissue biopsies, biochemical analytics, and informatics. Pairing these technologies with recent discoveries in epigenetic regulation, mitochondrial dynamics, and organ-microbiome metabolic crosstalk will garner critical mechanistic insights in heart failure. In this state-of-the-art review, we focus on new metabolic insights, with an eye on emerging metabolic strategies for heart failure. Our synthesis of the field will be valuable for a diverse audience with an interest in cardiac metabolism.
Introduction
Mung beans contain various antinutritional components. Processing and cooking methods can reduce these antinutritional factors and increase the availability and digestibility of nutrients. Resistant starch is also known as dietary fiber, which helps to reduce the cholesterol and glucose level in blood. It is formed during cooking and storage of food at low temperature.
Objectives
This study aimed to assess the effects of cooking and storage temperature on the formation of resistant starch in processed mung bean, as well as its effect on blood glucose levels and lipid profile in humans and rats.
Methods
The common cooking methods namely boiling, steaming after germination, roasting, and pressure cooking were chosen. The cooked samples were stored at different temperatures including freshly prepared within 1 h (T1), stored for 24 h at room temperature (20–22°C) (T2), kept at 4°C for 24 h (T3), and reheated after storing at 4°C for 24 h (T4).
Results
The study revealed that germinated-steamed mung beans had significantly higher levels of resistant starch (27.63 ± 0.76), and lower level of glycemic index (26.28 ± 3.08) and amylose (40.91 ± 0.06) when stored at 4°C for 24 h (T3) followed by (T2), (T4), and (T1) as compared to other cooking methods (boiling, pressure cooking, and roasting). The germinated-steamed mung beans (T1) resulted in 96% decline in blood glucose parameters of rats (36 Wistar albino rats aged 2 to 3 months were selected) than the control group as observed in 28 days diet intervention (100 mg/kg resistant starch orally).
Conclusion
There is a need to make people aware about the selection of appropriate cooking (steamed after germination) and storage methods (T3) to increase the RS content and to lower the glycemic index of food at domestic level.
Obesity and colorectal cancer are global public health issues, with the prevalence of both conditions increasing over the last 4 decades. In the United States alone, the prevalence of obesity is greater than 40%, and this percentage is projected to increase past 50% by 2030. This review focuses on understanding the association between obesity and the risk of colorectal cancer while also highlighting hypotheses about molecular mechanisms underlying the link between these disease processes. We also consider whether those linkages can be disrupted via weight loss therapies, including lifestyle modifications, pharmacotherapy, bariatric surgery, and endobariatrics.
This study aimed to develop the ‘Healthy Eating Index for Older People’ (the index), based on New Zealand dietary guidelines, and measures the validity and reproducibility of a food frequency questionnaire (FFQ) to derive the index scores in older adults. In Auckland, New Zealand, participants (community-dwelling adults aged 65–74 years, [n = 273, 36% male]) completed a 109-item FFQ administered one month apart (FFQ1, FFQ2), with a four-day food record (4-DFR) collected in between. Adherence to the guidelines was scored using the index, comprising a total score (maximum = 100) and two sub-scores: adequacy (maximum = 60) and moderation (maximum = 40). A comparison of FFQ1 and FFQ2 determined reproducibility, and FFQ1 and 4-DFR determined validity. Higher index scores (from FFQ1) were associated with higher intakes of protein, fibre, vitamins and minerals and lower intakes of alcohol and saturated fats (nutrients from 4-DFR) after adjusting for age and sex (all p < 0.001). Total index and sub-indices correlation coefficients ranged from 0.42 to 0.77 (all p < 0.001); weighted kappa values ranged from 0.35 to 0.67; and mean differences were all <10% of FFQ1 for reproducibility and validity. The Bland–Altman analysis showed no bias for the total index score for reproducibility and validity. However, with validation, the sub-index scores became less reliable as food intake increased (p < 0.05). The index applied to the FFQ demonstrated good construct validity and reproducibility. Relative and absolute validity were acceptable, though caution is required when using the absolute sub-index scores. The index is suitable for measuring total diet quality in older New Zealand adults.
Background
Some dietary recommendations continue to recommend carbohydrate restriction as a cornerstone of dietary advice for people with diabetes.
Purpose
We compared the cardiometabolic effects of diets higher in both fiber and carbohydrate with lower carbohydrate lower fiber diets in type 1 or type 2 diabetes.
Data sources
MEDLINE, Embase, and the Cochrane Database of Systematic Reviews up to June 24, 2024, with additional hand searching.
Study selection
Randomized controlled trials in which both dietary fiber and carbohydrate amount had been modified were identified from source evidence syntheses on carbohydrate amount in people with diabetes.
Data extraction
Two reviewers independently.
Data synthesis
Ten eligible trials including 499 participants with diabetes (98% with T2) were identified from the potentially eligible 828 trials included in existing evidence syntheses. Pooled findings indicate that higher fiber higher carbohydrate diets reduced HbA1c (mean difference [MD] −0.50% [95% confidence interval −0.99 to −0.02]), fasting insulin (MD −0.99 μIU/mL [−1.83 to −0.15]), total cholesterol (MD −0.16 mmol/L [−0.27 to −0.05]) and low‐density lipoprotein cholesterol (MD −0.16 mmol/L (−0.31 to −0.01) when compared with lower carbohydrate lower fiber diets. Trials with larger differences in fiber and carbohydrate intakes between interventions reported greater reductions. Certainty of evidence for these outcomes was moderate or high, with most outcomes downgraded due to heterogeneity unexplained by any single variable.
Limitations
Our predefined scope excluded trials with co‐interventions such as energy restriction, which may have provided addition information.
Conclusions
Findings indicate the greater importance of promoting dietary fiber intakes, and the relative unimportance of carbohydrate amount in recommendations for people with diabetes.
Every year, atherosclerotic cardiovascular disease (ASCVD) kills the most individuals worldwide. Unfortunately, the foundation for the disease starts early on in life. However, healthful plant-based diets can help reduce the risk of ASCVD (e.g., coronary artery disease, stroke, heart failure, erectile dysfunction), and its risk factors (e.g., hypertension, diabetes, dyslipidemia, and obesity). The components (macronutrients and micronutrients) of whole-food plant-based diets modulate inflammation and promote a healthy microbiome, among other benefits. Based on the current literature, the authors propose consuming a whole-food plant-based diet (in conjunction with other healthful lifestyle habits) to decrease the risk of ASCVD and its risk factors.
This chapter discusses the evidence behind dietary and lifestyle modifications that aid in the reduction of cancer risk are synergistic with cancer therapies and improve long-term outcomes in survivors. Whole-food, plant-based (WFPB) diets may work to reduce cancer risk by helping maintain a healthy weight; increase dietary fiber, phytochemicals, short-chain fatty acids such as butyrate; and reduce inflammation, insulin resistance, and insulin-like growth factor 1 (IGF-1) levels. We also include practical guidance on transitioning to a more whole-foods, plant-based diet including resources for further information.
Research into the analysis, physical properties and health effects of dietary fibre has continued steadily over the last 40–50 years. From the knowledge gained, countries have developed guidelines for their populations on the optimal amount of fibre to be consumed each day. Food composition tables from many countries now contain values for the dietary fibre content of foods, and, from these, combined with dietary surveys, population intakes have been determined. The present review assessed the uniformity of the analytical methods used, health claims permitted, recommendations and intakes, particularly from national surveys across Europe and around the world. It also assessed current knowledge on health effects of dietary fibre and related the impact of different fibre types on health. The overall intent was to be able to provide more detailed guidance on the types of fibre which should be consumed for good health, rather than simply a total intake figure, the current situation. Analysis of data indicated a fair degree of uniformity in the definition of dietary fibre, the method used for analysis, the recommended amount to be consumed and a growing literature on effects on digestive health and disease risk. However, national dietary survey data showed that intakes do not reach recommendations and very few countries provide guidance on the types of fibre that are preferable to achieve recommended intakes. Research gaps were identified and ideas suggested to provide information for more detailed advice to the public about specific food sources that should be consumed to achieve health benefits.
For more than 200 years the fibre in plant foods has been known by animal nutritionists to have significant effects on digestion. Its role in human nutrition began to be investigated towards the end of the 19th century. However, between 1966 and 1972, Denis Burkitt, a surgeon who had recently returned from Africa, brought together ideas from a range of disciplines together with observations from his own experience to propose a radical view of the role of fibre in human health. Burkitt came late to the fibre story but built on the work of three physicians (Peter Cleave, G. D. Campbell and Hugh Trowell), a surgeon (Neil Painter) and a biochemist (Alec Walker) to propose that diets low in fibre increase the risk of CHD, obesity, diabetes, dental caries, various vascular disorders and large bowel conditions such as cancer, appendicitis and diverticulosis. Simply grouping these diseases together as having a common cause was groundbreaking. Proposing fibre as the key stimulated much research but also controversy. Credit for the dietary fibre hypothesis is given largely to Burkitt who became known as the ‘Fibre Man’. This paper sets out the story of the development of the fibre hypothesis, and the contribution to it of these individuals.
To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.
Background:
Questions remain about the strength and shape of the dose-response relationship between fruit and vegetable intake and risk of cardiovascular disease, cancer and mortality, and the effects of specific types of fruit and vegetables. We conducted a systematic review and meta-analysis to clarify these associations.
Methods:
PubMed and Embase were searched up to 29 September 2016. Prospective studies of fruit and vegetable intake and cardiovascular disease, total cancer and all-cause mortality were included. Summary relative risks (RRs) were calculated using a random effects model, and the mortality burden globally was estimated; 95 studies (142 publications) were included.
Results:
For fruits and vegetables combined, the summary RR per 200 g/day was 0.92 [95% confidence interval (CI): 0.90-0.94, I 2 = 0%, n = 15] for coronary heart disease, 0.84 (95% CI: 0.76-0.92, I 2 = 73%, n = 10) for stroke, 0.92 (95% CI: 0.90-0.95, I 2 = 31%, n = 13) for cardiovascular disease, 0.97 (95% CI: 0.95-0.99, I 2 = 49%, n = 12) for total cancer and 0.90 (95% CI: 0.87-0.93, I 2 = 83%, n = 15) for all-cause mortality. Similar associations were observed for fruits and vegetables separately. Reductions in risk were observed up to 800 g/day for all outcomes except cancer (600 g/day). Inverse associations were observed between the intake of apples and pears, citrus fruits, green leafy vegetables, cruciferous vegetables, and salads and cardiovascular disease and all-cause mortality, and between the intake of green-yellow vegetables and cruciferous vegetables and total cancer risk. An estimated 5.6 and 7.8 million premature deaths worldwide in 2013 may be attributable to a fruit and vegetable intake below 500 and 800 g/day, respectively, if the observed associations are causal.
Conclusions:
Fruit and vegetable intakes were associated with reduced risk of cardiovascular disease, cancer and all-cause mortality. These results support public health recommendations to increase fruit and vegetable intake for the prevention of cardiovascular disease, cancer, and premature mortality.
Objective:
To quantify the dose-response relation between consumption of whole grain and specific types of grains and the risk of cardiovascular disease, total cancer, and all cause and cause specific mortality.
Data sources:
PubMed and Embase searched up to 3 April 2016.
Study selection:
Prospective studies reporting adjusted relative risk estimates for the association between intake of whole grains or specific types of grains and cardiovascular disease, total cancer, all cause or cause specific mortality.
Data synthesis:
Summary relative risks and 95% confidence intervals calculated with a random effects model.
Results:
45 studies (64 publications) were included. The summary relative risks per 90 g/day increase in whole grain intake (90 g is equivalent to three servings-for example, two slices of bread and one bowl of cereal or one and a half pieces of pita bread made from whole grains) was 0.81 (95% confidence interval 0.75 to 0.87; I(2)=9%, n=7 studies) for coronary heart disease, 0.88 (0.75 to 1.03; I(2)=56%, n=6) for stroke, and 0.78 (0.73 to 0.85; I(2)=40%, n=10) for cardiovascular disease, with similar results when studies were stratified by whether the outcome was incidence or mortality. The relative risks for morality were 0.85 (0.80 to 0.91; I(2)=37%, n=6) for total cancer, 0.83 (0.77 to 0.90; I(2)=83%, n=11) for all causes, 0.78 (0.70 to 0.87; I(2)=0%, n=4) for respiratory disease, 0.49 (0.23 to 1.05; I(2)=85%, n=4) for diabetes, 0.74 (0.56 to 0.96; I(2)=0%, n=3) for infectious diseases, 1.15 (0.66 to 2.02; I(2)=79%, n=2) for diseases of the nervous system disease, and 0.78 (0.75 to 0.82; I(2)=0%, n=5) for all non-cardiovascular, non-cancer causes. Reductions in risk were observed up to an intake of 210-225 g/day (seven to seven and a half servings per day) for most of the outcomes. Intakes of specific types of whole grains including whole grain bread, whole grain breakfast cereals, and added bran, as well as total bread and total breakfast cereals were also associated with reduced risks of cardiovascular disease and/or all cause mortality, but there was little evidence of an association with refined grains, white rice, total rice, or total grains.
Conclusions:
This meta-analysis provides further evidence that whole grain intake is associated with a reduced risk of coronary heart disease, cardiovascular disease, and total cancer, and mortality from all causes, respiratory diseases, infectious diseases, diabetes, and all non-cardiovascular, non-cancer causes. These findings support dietary guidelines that recommend increased intake of whole grain to reduce the risk of chronic diseases and premature mortality.
Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field [1],[2], and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research [3], and some health care journals are moving in this direction [4]. As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews.
Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in four leading medical journals in 1985 and 1986 and found that none met all eight explicit scientific criteria, such as a quality assessment of included studies [5]. In 1987, Sacks and colleagues [6] evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in six domains. Reporting was generally poor; between one and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement [7].
In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials [8]. In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1).
Box 1: Conceptual Issues in the Evolution from QUOROM to PRISMA
Completing a Systematic Review Is an Iterative Process
The conduct of a systematic review depends heavily on the scope and quality of included studies: thus systematic reviewers may need to modify their original review protocol during its conduct. Any systematic review reporting guideline should recommend that such changes can be reported and explained without suggesting that they are inappropriate. The PRISMA Statement (Items 5, 11, 16, and 23) acknowledges this iterative process. Aside from Cochrane reviews, all of which should have a protocol, only about 10% of systematic reviewers report working from a protocol [22]. Without a protocol that is publicly accessible, it is difficult to judge between appropriate and inappropriate modifications.
Systematic reviews are generally considered to provide the most reliable form of evidence to guide decision makers. Here we describe ROBIS, a new tool for assessing the risk of bias in systematic reviews (rather than in primary studies). ROBIS has been developed using rigorous methodology and is currently aimed at four broad categories of reviews mainly within healthcare settings: interventions, diagnosis, prognosis and aetiology. The target audience of ROBIS is primarily guideline developers, authors of overviews of systematic reviews ("reviews of reviews") and review authors who might want to assess or avoid risk of bias in their reviews. The tool is completed in 3 phases: (1) assess relevance (optional), (2) identify concerns with the review process and (3) judge risk of bias. Phase 2 covers four domains through which bias may be introduced into a systematic review: study eligibility criteria; identification and selection of studies; data collection and study appraisal; and synthesis and findings. Phase 3 assesses the overall risk of bias in the interpretation of review findings and whether this considered limitations identified in any of the Phase 2 domains. Signalling questions are included to help judge concerns with the review process (Phase 2) and the overall risk of bias in the review (Phase 3); these questions flag aspects of review design related to the potential for bias and aim to help assessors judge risk of bias in the review process, results and conclusions.
Copyright © 2015 Elsevier Inc. All rights reserved.
To summarise evidence on the association between intake of dietary sugars and body weight in adults and children.
Systematic review and meta-analysis of randomised controlled trials and prospective cohort studies.
OVID Medline, Embase, PubMed, Cumulative Index to Nursing and Allied Health Literature, Scopus, and Web of Science (up to December 2011).
Eligible studies reported the intake of total sugars, intake of a component of total sugars, or intake of sugar containing foods or beverages; and at least one measure of body fatness. Minimum duration was two weeks for trials and one year for cohort studies. Trials of weight loss or confounded by additional medical or lifestyle interventions were excluded. Study selection, assessment, validity, data extraction, and analysis were undertaken as specified by the Cochrane Collaboration and the GRADE working group. For trials, we pooled data for weight change using inverse variance models with random effects. We pooled cohort study data where possible to estimate effect sizes, expressed as odds ratios for risk of obesity or β coefficients for change in adiposity per unit of intake.
30 of 7895 trials and 38 of 9445 cohort studies were eligible. In trials of adults with ad libitum diets (that is, with no strict control of food intake), reduced intake of dietary sugars was associated with a decrease in body weight (0.80 kg, 95% confidence interval 0.39 to 1.21; P<0.001); increased sugars intake was associated with a comparable weight increase (0.75 kg, 0.30 to 1.19; P=0.001). Isoenergetic exchange of dietary sugars with other carbohydrates showed no change in body weight (0.04 kg, -0.04 to 0.13). Trials in children, which involved recommendations to reduce intake of sugar sweetened foods and beverages, had low participant compliance to dietary advice; these trials showed no overall change in body weight. However, in relation to intakes of sugar sweetened beverages after one year follow-up in prospective studies, the odds ratio for being overweight or obese increased was 1.55 (1.32 to 1.82) among groups with the highest intake compared with those with the lowest intake. Despite significant heterogeneity in one meta-analysis and potential bias in some trials, sensitivity analyses showed that the trends were consistent and associations remained after these studies were excluded.
Among free living people involving ad libitum diets, intake of free sugars or sugar sweetened beverages is a determinant of body weight. The change in body fatness that occurs with modifying intakes seems to be mediated via changes in energy intakes, since isoenergetic exchange of sugars with other carbohydrates was not associated with weight change.
Glycemic index (GI) and glycemic load (GL) have been associated with coronary heart disease (CHD) risk in some but not all cohort studies. We therefore assessed the association of GI and GL with CHD risk in prospective cohorts.
We searched MEDLINE, EMBASE, and CINAHL (through April 5, 2012) and identified all prospective cohorts assessing associations of GI and GL with incidence of CHD. Meta-analysis of observational studies in epidemiology (MOOSE) methodologies were used. Relative measures of risk, comparing the group with the highest exposure (mean GI of cohorts=84.4 GI units, range 79.9 to 91; mean GL of cohorts=224.8, range 166 to 270) to the reference group (mean GI=72.3 GI units, range 68.1 to 77; mean GL=135.4, range 83 to 176), were pooled using random-effects models, expressed as relative risk (RR) with heterogeneity assessed by χ(2) and quantified by I(2). Subgroups included sex and duration of follow-up. Ten studies (n=240 936) were eligible. Pooled analyses showed an increase in CHD risk for the highest GI quantile compared with the lowest, with RR=1.11 (95% confidence interval [CI] 0.99 to 1.24) and for GL, RR=1.27 (95% CI 1.09 to 1.49), both with evidence of heterogeneity (I(2)>42%, P<0.07). Subgroup analyses revealed only a significant modification by sex, with the female cohorts showing significance for GI RR=1.26 (95% CI 1.12 to 1.41) and for GL RR=1.55 (95% CI 1.18 to 2.03).
High GI and GL diets were significantly associated with CHD events in women but not in men. Further studies are required to determine the relationship between GI and GL with CHD in men.
The relationship between dietary glycemic index, glycemic load and risk of coronary heart disease (CHD), stroke, and stroke-related mortality is inconsistent.
We systematically searched the MEDLINE, EMBASE, and Science Citation Index Expanded databases using glycemic index, glycemic load, and cardiovascular disease and reference lists of retrieved articles up to April 30, 2012. We included prospective studies with glycemic index and glycemic load as the exposure and incidence of fatal and nonfatal CHD, stroke, and stroke-related mortality as the outcome variable. Pooled relative risks (RR) and 95% confidence intervals (CI) were calculated using random-effects models.
Fifteen prospective studies with a total of 438,073 participants and 9,424 CHD cases, 2,123 stroke cases, and 342 deaths from stroke were included in the meta-analysis. Gender significantly modified the effects of glycemic index and glycemic load on CHD risk, and high glycemic load level was associated with higher risk of CHD in women (RR = 1.49, 95%CI 1.27-1.73), but not in men (RR = 1.08, 95%CI 0.91-1.27). Stratified meta-analysis by body mass index indicated that among overweight and obese subjects, dietary glycemic load level were associated with increased risk of CHD (RR = 1.49, 95%CI 1.27-1.76; P for interaction = 0.003). Higher dietary glycemic load, but not glycemic index, was positively associated with stroke (RR = 1.19, 95% CI 1.00-1.43). There is a linear dose-response relationship between dietary glycemic load and increased risk of CHD, with pooled RR of 1.05 (95%CI 1.02-1.08) per 50-unit increment in glycemic load level.
High dietary glycemic load is associated with a higher risk of CHD and stroke, and there is a linear dose-response relationship between glycemic load and CHD risk. Dietary glycemic index is slightly associated with risk of CHD, but not with stroke and stroke-related death. Further studies are needed to verify the effects of gender and body weight on cardiovascular diseases.
Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30
To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.
Systematic review and meta-analysis of prospective observational studies.
PubMed and several other databases up to December 2010 and the reference lists of studies included in the analysis as well as those listed in published meta-analyses.
Prospective cohort and nested case-control studies of dietary fibre or whole grain intake and incidence of colorectal cancer.
25 prospective studies were included in the analysis. The summary relative risk of developing colorectal cancer for 10 g daily of total dietary fibre (16 studies) was 0.90 (95% confidence interval 0.86 to 0.94, I(2) = 0%), for fruit fibre (n = 9) was 0.93 (0.82 to 1.05, I(2) = 23%), for vegetable fibre (n = 9) was 0.98 (0.91 to 1.06, I(2) = 0%), for legume fibre (n = 4) was 0.62 (0.27 to 1.42, I(2) = 58%), and for cereal fibre (n = 8) was 0.90 (0.83 to 0.97, I(2) = 0%). The summary relative risk for an increment of three servings daily of whole grains (n = 6) was 0.83 (0.78 to 0.89, I(2) = 18%).
A high intake of dietary fibre, in particular cereal fibre and whole grains, was associated with a reduced risk of colorectal cancer. Further studies should report more detailed results, including those for subtypes of fibre and be stratified by other risk factors to rule out residual confounding. Further assessment of the impact of measurement errors on the risk estimates is also warranted.
To systematically tabulate published and unpublished sources of reliable glycemic index (GI) values.
A literature search identified 205 articles published between 1981 and 2007. Unpublished data were also included where the data quality could be verified. The data were separated into two lists: the first representing more precise data derived from testing healthy subjects and the second primarily from individuals with impaired glucose metabolism.
The tables, which are available in the online-only appendix, list the GI of over 2,480 individual food items. Dairy products, legumes, and fruits were found to have a low GI. Breads, breakfast cereals, and rice, including whole grain, were available in both high and low GI versions. The correlation coefficient for 20 staple foods tested in both healthy and diabetic subjects was r = 0.94 (P < 0.001).
These tables improve the quality and quantity of GI data available for research and clinical practice.
For nutritional purposes, starch in foods may be classified into rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). RS may be further divided into three categories according to the reason for resistance to digestion. A method is reported for the measurement of total starch, RDS, SDS, RS and three RS fractions in starchy foods, using controlled enzymic hydrolysis with pancreatin and amyloglucosidase. The released glucose is measured by colorimetry, using a glucose oxidase kit. Values for RDS and SDS in foods obtained by the method reflect the rate of starch digestion in vivo. Values for RS are similar to the amounts of starch escaping digestion in the small intestine of ileostomates, and are a guide to the amounts of starch likely to enter the colon for fermentation. Results are given for a number of starchy foods.
To evaluate the effects of varying the glycemic index (GI) of carbohydrate-rich foods on metabolic control in type 2 diabetic patients.
In a randomized crossover study, 20 patients, 5 women and 15 men, were given preweighed diets with different GIs during two consecutive 24-day periods. Both diets were composed in accordance with dietary recommendations for people with diabetes. The macronutrient composition and type and amount of dietary fiber were identical. Differences in GI were achieved mainly by altering the structure of the starchy foods.
Peripheral insulin sensitivity increased significantly and fasting plasma glucose decreased during both treatment periods. There was a significant difference in the changes of serum fructosamine concentrations between the diets (P < 0.05). The incremental area under the curve for both blood glucose and plasma insulin was approximately 30% lower after the low- than after the high-GI diet. LDL cholesterol was significantly lowered on both diets, with a significantly more pronounced reduction on the low-GI diet. Plasminogen activator inhibitor-1 activity was normalized on the low-GI diet, (-54%, P < 0.001), but remained unchanged on the high-GI diet.
A diet characterized by low-GI starchy foods lowers the glucose and insulin responses throughout the day and improves the lipid profile and capacity for fibrinolysis, suggesting a therapeutic potential in diabetes.
We study recently developed nonparametric methods for estimating the number of missing studies that might exist in a meta-analysis and the effect that these studies might have had on its outcome. These are simple rank-based data augmentation techniques, which formalize the use of funnel plots. We show that they provide effective and relatively powerful tests for evaluating the existence of such publication bias. After adjusting for missing studies, we find that the point estimate of the overall effect size is approximately correct and coverage of the effect size confidence intervals is substantially improved, in many cases recovering the nominal confidence levels entirely. We illustrate the trim and fill method on existing meta-analyses of studies in clinical trials and psychometrics.
Iron and zinc are currently the trace minerals of greatest concern when considering the nutritional value of vegetarian diets. With elimination of meat and increased intake of phytate-containing legumes and whole grains, the absorption of both iron and zinc is lower with vegetarian than with nonvegetarian, diets. The health consequences of lower iron and zinc bioavailability are not clear, especially in industrialized countries with abundant, varied food supplies, where nutrition and health research has generally supported recommendations to reduce meat and increase legume and whole-grain consumption. Although it is clear that vegetarians have lower iron stores, adverse health effects from lower iron and zinc absorption have not been demonstrated with varied vegetarian diets in developed countries, and moderately lower iron stores have even been hypothesized to reduce the risk of chronic diseases. Premenopausal women cannot easily achieve recommended iron intakes, as modified for vegetarians, with foods alone; however, the benefit of routine iron supplementation has not been demonstrated. It may be prudent to monitor the hemoglobin of vegetarian children and women of childbearing age. Improved assessment methods are required to determine whether vegetarians are at risk of zinc deficiency. In contrast with iron and zinc, elements such as copper appear to be adequately provided by vegetarian diets. Although the iron and zinc deficiencies commonly associated with plant-based diets in impoverished nations are not associated with vegetarian diets in wealthier countries, these nutrients warrant attention as nutritional assessment methods become more sensitive and plant-based diets receive greater emphasis.
Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice?
Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis.
Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4
Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted?
A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …
Guidelines are inconsistent in how they rate the quality of evidence and the strength of recommendations. This article explores the advantages of the GRADE system, which is increasingly being adopted by organisations worldwide Summary points Failure to consider the quality of evidence can lead to misguided recommendations; hormone replacement therapy for post-menopausal women provides an instructive example High quality evidence that an intervention’s desirable effects are clearly greater than its undesirable effects, or are clearly not, warrants a strong recommendationUncertainty about the trade-offs (because of low quality evidence or because the desirable and undesirable effects are closely balanced) warrants a weak recommendationGuidelines should inform clinicians what the quality of the underlying evidence is and whether recommendations are strong or weakThe Grading of Recommendations Assessment, Development and Evaluation (GRADE ) approach provides a system for rating quality of evidence and strength of recommendations that is explicit, comprehensive, transparent, and pragmatic and is increasingly being adopted by organisations worldwideGuideline developers around the world are inconsistent in how they rate quality of evidence and grade strength of recommendations. As a result, guideline users face challenges in understanding the messages that grading systems try to communicate. Since 2006 the BMJ has requested in its “Instructions to Authors” on bmj.com that authors should preferably use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system for grading evidence when submitting a clinical guidelines article. What was behind this decision?In this first in a series of five articles we will explain why many organisations use formal systems to grade evidence and recommendations and why this is important for clinicians; we will focus on the GRADE approach to recommendations. In the next two articles we will examine how the GRADE system categorises quality of evidence and strength of recommendations. The final two articles will …
Dietary fiber is widely recognized as an essential element of good nutrition. In fact, research on the use of fiber in food science and medicine is being conducted at an incredible pace. CRC Handbook of Dietary Fiber in Human Nutrition, Third Edition explores the chemistry, analytical methodologies, physiological and biochemical aspects, clinical and epidemiological studies, and consumption patterns of dietary fiber. Featuring new chapters and tables, in addition to updated sections, the third edition of this popular book includes important information that has become available since the publication of the second edition. What’s new in the Third Edition? o Definitions and consumption of dietary fiber from 1992-2000 o A new chapter on the physical chemistry of dietary fiber o Updated dietary fiber values for common foods o New table: Tartaric Acid Content of Foods o Coverage of non-plant food fibers, such as chitin and chitosan o An entire section devoted to the effect of whole grains, cereal fiber, and phytic acid on health o Discussion of the interaction of fiber and phytochemicals Quickly retrieve and understand current data with the book’s concise, easy-to-read tables and definitions. Covering all aspects of dietary fiber, including chemistry and definitions, analytical procedures, and basic physiological functions, the CRC Handbook of Dietary Fiber in Human Nutrition provides you with a unique collection of dietary fiber information unlike that found in any other book.
Objective:
To develop ROBIS, a new tool for assessing the risk of bias in systematic reviews (rather than in primary studies).
Study design and setting:
We used four-stage approach to develop ROBIS: define the scope, review the evidence base, hold a face-to-face meeting, and refine the tool through piloting.
Results:
ROBIS is currently aimed at four broad categories of reviews mainly within health care settings: interventions, diagnosis, prognosis, and etiology. The target audience of ROBIS is primarily guideline developers, authors of overviews of systematic reviews ("reviews of reviews"), and review authors who might want to assess or avoid risk of bias in their reviews. The tool is completed in three phases: 1) assess relevance (optional), 2) identify concerns with the review process, and 3) judge risk of bias. Phase 2 covers four domains through which bias may be introduced into a systematic review: 1) study eligibility criteria; 2) identification and selection of studies; 3) data collection and study appraisal; and 4) synthesis and findings. Phase 3 assesses the overall risk of bias in the interpretation of review findings and whether this considered limitations identified in any of the phase 2 domains. Signaling questions are included to help judge concerns with the review process (phase 2) and the overall risk of bias in the review (phase 3); these questions flag aspects of review design related to the potential for bias and aim to help assessors judge risk of bias in the review process, results, and conclusions.
Conclusions:
ROBIS is the first rigorously developed tool designed specifically to assess the risk of bias in systematic reviews.
Importance
Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets.
Objective
To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss.
Design, Setting, and Participants
The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss.
Interventions
Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality.
Main Outcomes and Measures
Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss.
Results
Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was −5.3 kg for the HLF diet vs −6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, −0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups.
Conclusions and Relevance
In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom.
Trial Registration
clinicaltrials.gov Identifier: NCT01826591
Advances in microbiome science cast light on traditional concepts on nutritional science, and are poised for clinical translation. Epidemiologic observations which linked lifestyle factors to risk of disease are being re-interpreted with mechanistic insight based on improved understanding of the microbiota. Examples include the role of dietary fibre in disease prevention, the deleterious effects of highly restricted diets, and the contribution of the microbiota to over- and undernutrition. While the microbiota transduces nutrient signals for the host, food and habitual diet shape the composition of the gut microbiota at every stage of life. The composition and diversity of food intake determines which microbes will colonise, flourish, persist, or become extinct. Disruption of the developing microbiota in infancy contributes to the risk of immune and metabolic disease in later life, whereas loss of microbes in the elderly due to monotonous diets has been linked with unhealthy ageing and frailty. This should influence modern dietary advice regarding prevention and management of chronic non-communicable inflammatory and metabolic disorders, and will inform the design of infant and future food formula. The microbiota profile is also emerging as a biomarker to predict responsiveness to dietary interventions and promises to make personalised nutrition a reality.
This paper presents a command, glst, for trend estimation across different exposure levels for either single or multiple summarized case-control, incidence-rate, and cumulative incidence data. This approach is based on constructing an approximate covariance estimate for the log relative risks and estimating a corrected linear trend using generalized least squares. For trend analysis of multiple studies, glst can estimate fixed- and random-effects metaregression models. Copyright 2006 by StataCorp LP.
To obtain an up-to-date quantification of the association between dietary glycemic index (GI) and glycemic load (GL) and the risk of cancer.
We conducted a systematic review and meta-analysis of observational studies updated January 2015. Summary relative risks (RR) were derived using random-effects models. Seventy-five reports were evaluated in the systematic review (147090 cases), and 72 were included in the meta-analyses. Considering hormone-related cancers, summary RRs comparing the highest versus the lowest GI and GL intake were, respectively, 1.05 and 1.07 for breast, 1.13 and 1.17 for endometrial, 1.11 and 1.19 for ovarian, and 1.06 and 1.04 for prostate cancers. Considering digestive-tract cancers, summary RRs for GI and GL were, respectively, 1.46 and 1.25 for esophageal (squamous cell carcinoma), 1.17 and 1.10 for stomach, 1.16 (significant) and 1.10 for colorectal, 1.11 and 1.14 for liver, and 1.10 and 1.01 for pancreatic cancers. In most of these meta-analyses, significant heterogeneity among studies was observed. In subgroup analyses, case-control studies and studies from Europe tended to estimate higher RRs.
High GI and GL diets are related to moderately increased risk of cancer at several common sites. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Aims: The present meta-analysis aimed to investigate fiber consumption and all-cause mortality, and cause-specific mortality.Methods: Medline and web of science database were searched for cohort studies published from inception to August 2014.Studies were included if they provided a hazard ratio (HR) and corresponding 95% CI for mortality in relation to fiber consumption.Results: Compared with those who consumed lowest fiber, for individuals who ate highest fiber, mortality rate was lower by 23% (HR, 0.77; 95% CI, 0.72-0.81) for CVD, by 17% (HR, 0.83; 95% CI, 0.74- 0.91) for cancer, by 23% (HR, 0.77; 95% CI, 0.73-0.81) for all-cause mortality. For each 10 gram/day increase in fiber intake, the pooled HR was estimated to be 0.89 (95% CI, 0.86-0.93) for all-cause mortality, 0.80 (95% CI, 0.72-0.88) for CHD mortality, and 0.66 (95% CI, 0.40-0.92) for IHD mortality, 0.91 (95% CI, 0.88-0.94) for cancer. Dietary fiber and CVD mortality showed a strong dose-response relation.Conclusions: Fiber consumption is inversely associated with all-cause mortality and CVD, IHD, cancer mortality.This article is protected by copyright. All rights reserved
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Epidemiologic evidence for the relation between carbohydrate quality and risk of type 2 diabetes (T2D) has been mixed.
We prospectively examined the association of dietary glycemic index (GI) and glycemic load (GL) with T2D risk.
We prospectively followed 74,248 women from the Nurses' Health Study (1984-2008), 90,411women from the Nurses' Health Study II (1991-2009), and 40,498 men from the Health Professionals Follow-Up Study (1986-2008) who were free of diabetes, cardiovascular disease, and cancer at baseline. Diet was assessed by using a validated questionnaire and updated every 4 y. We also conducted an updated meta-analysis, including results from our 3 cohorts and other studies.
During 3,800,618 person-years of follow-up, we documented 15,027 cases of incident T2D. In pooled multivariable analyses, those in the highest quintile of energy-adjusted GI had a 33% higher risk (95% CI: 26%, 41%) of T2D than those in the lowest quintile. Participants in the highest quintile of energy-adjusted GL had a 10% higher risk (95% CI: 2%, 18%) of T2D. Participants who consumed a combination diet that was high in GI or GL and low in cereal fiber had an ∼50% higher risk of T2D. In the updated meta-analysis, the summary RRs (95% CIs) comparing the highest with the lowest categories of GI and GL were 1.19 (1.14, 1.24) and 1.13 (1.08, 1.17), respectively.
The updated analyses from our 3 cohorts and meta-analyses provide further evidence that higher dietary GI and GL are associated with increased risk of T2D.
High glycemic load (GL) has been associated with excess stroke risk. Data suggest a different role of diet in the etiology of ischemic and hemorrhagic stroke.
We analyzed data from 19,824 participants of the Greek cohort of the population-based European Prospective Investigation into Cancer and nutrition (EPIC), who were free of cardiovascular diseases, cancer, and diabetes at baseline and had not developed diabetes. Diet was assessed at enrollment through a validated, interviewer-administered semi-quantitative food frequency questionnaire. The average daily GL was derived using standard tables. We also conducted a meta-analysis on GL and stroke (overall, ischemic and hemorrhagic), using random-effects models.
In the Greek EPIC cohort, 304 incident stroke cases were identified (67 ischemic, 49 hemorrhagic). Using Cox proportional hazards regression models adjusted for potential confounders, the hazard ratios for the highest versus the lowest GL tertiles were 1.07 [95 % confidence interval (CI) 0.74-1.54] for overall stroke, 1.55 (95 % CI 0.72-3.36) for ischemic and 0.48 (95 % CI 0.18-1.25) for hemorrhagic stroke (p-heterogeneity <0.01). The meta-analysis, including a total of 3,088 incident cases and 247 deaths from stroke (1,469 cases and 126 deaths ischemic; 576 cases and 94 deaths hemorrhagic), estimated pooled relative risks for the highest versus the lowest GL levels of 1.23 (95 % CI 1.07-1.41) for overall, 1.35 (95 % CI 1.06-1.72) for ischemic, and 1.09 (95 % CI 0.81-1.47) for hemorrhagic stroke (p-heterogeneity = 0.275).
This study indicates that GL is an important determinant of the more common ischemic-though not of the hemorrhagic-stroke.
Epidemiologic studies have shown that fiber intake is associated with a lower body weight. Satiety and energy intake are possible explanations for this effect. The purpose of this study was to recommend fiber types and doses that are effective in reducing appetite and energy intake. A systematic review was conducted using the American Dietetic Association's evidence analysis process as a guide. Studies were identified from PubMed and bibliographies of review articles. Studies measuring appetite, food and/or energy intake with a treatment period of ≤24 hours, a reported fiber type and amount, a low- or no-fiber control, and healthy human participants were included. Forty-four publications were identified, from which 107 treatments were analyzed. Thirty-eight fiber sources were identified. The percentage of treatments that significantly reduced subjective appetite rating compared with the control was 39%. The percentage that significantly reduced food or energy intake was 22%. The satiety-enhancing effects of β-glucan, lupin kernel fiber, rye bran, whole grain rye, or a mixed high-fiber diet were supported in more than one publication. Most fibers do not reduce appetite or energy intake in acute study designs. Key teaching points: • Dietary fiber intake is associated with lower body weight in epidemiologic studies. • Most acute fiber treatments (61%) did not enhance satiety. • Most acute fiber treatments (78%) did not reduce food intake. • Neither fiber type nor fiber dose were related to satiety response or food intake.
Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases; however, there are no comprehensive and quantitative assessments of available data in humans. The aim of this study was to systematically examine longitudinal studies investigating whole-grain and fiber intake in relation to risk of type 2 diabetes (T2D), cardiovascular disease (CVD), weight gain, and metabolic risk factors. We identified 45 prospective cohort studies and 21 randomized-controlled trials (RCT) between 1966 and February 2012 by searching the Cumulative Index to Nursing and Allied Health Literature, Cochrane, Elsevier Medical Database, and PubMed. Study characteristics, whole-grain and dietary fiber intakes, and risk estimates were extracted using a standardized protocol. Using random effects models, we found that compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of T2D [RR = 0.74 (95% CI: 0.69, 0.80)], ~21% lower risk of CVD [RR = 0.79 (95% CI: 0.74, 0.85)], and consistently less weight gain during 8-13 y (1.27 vs 1.64 kg; P = 0.001). Among RCT, weighted mean differences in post-intervention circulating concentrations of fasting glucose and total and LDL-cholesterol comparing whole-grain intervention groups with controls indicated significantly lower concentrations after whole-grain interventions [differences in fasting glucose: -0.93 mmol/L (95% CI: -1.65, -0.21), total cholesterol: -0.83 mmol/L (-1.24, -0.42); and LDL-cholesterol: -0.72 mmol/L (-1.34, -0.11)]. Findings from this meta-analysis provide evidence to support beneficial effects of whole-grain intake on vascular disease prevention. Potential mechanisms responsible for whole grains' effects on metabolic intermediates require further investigation in large intervention trials.