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Health Benefits of Oat Phytochemicals
Abstract
As a unique whole grain with multifunctional characteristics, oats and oat products have gained popularity with known benefits in the prevention of cardiovascular disease, coronary heart disease, hypertension, type 2 diabetes, obesity, and colon health. Phytochemicals in oats play important roles in these health benefits. β-glucan content in oats is higher than in other whole grains and can reach around 10% of the dry weight of oat bran. Syringaresinol is the predominant lignan in oats; it is a precursor of mammalian lignans. Avenanthramides are a group of alkaloids first discovered in oats and their health benefits are closely related to their antioxidant activity. Phytosterols found in oats include β-sitosterol, sitostanol, campesterol, campestanol, and others. Phenolics, carotenoids, and vitamin E are also commonly found in oats. In this paper, those oat phytochemicals and the health benefits associated with their consumption are reviewed.
... Oat seeds and other oat products are classified as functional foods due to their high content of β-glucans, polyunsaturated fatty acids, phytosterols, antioxidant compounds such as polyphenolic acids, tocols, phytic acid and avenanthramides (Lange, 2010). Also, the research data of numerous authors indicate that the health benefits of consuming oat seeds are related to the content of (1, Cui and Liu, 2013). A number of epidemiological studies indicate that the intake of oat products is associated with a reduced risk of type 2 diabetes and the maintenance of normal blood sugar levels (Ciu and Liu, 2013). ...
... β-Glucan is the main active component of oats,Sang and Chu (2017) report, primarily due to lowering intestinal glucose absorption and blood cholesterol, thereby preventing numerous inflammatory conditions, type 2 diabetes, hypertension, dyslipidemia(Alemayehu et al., 2023). Also, β-glucan maintains a healthy digestive and intestinal system(Cui and Liu, 2013). The wheat protein gliadin is known to cause inflammation in celiac patients. ...
... Recent studies demonstrated the bioaccessibility and bioavailability of plant lignans during digestion and fermentation in foodstuffs (13,14). Grain such as wheat, corn, rice, oats, millet, barley, spelt, and rye, are commonly consumed worldwide (15,16). Various studies have investigated the absorption and role of dietary lignans from grains (17)(18)(19). ...
Lignans are phytoestrogens found in various forms such as glycosides, ester-linked oligomers, and aglycones in a variety of foods, including soy products, legumes, grains, nuts, vegetables, and fruits. This study aimed to optimize the extraction of lignans from cereal grains using response surface methodology (RSM). Lignans, including secoisolariciresinol (Seco), matairesinol (Mat), pinoresinol (Pin), lariciresinol (Lar), and syringaresinol (Syr), were quantified using high-performance liquid chromatography–tandem mass spectrometry. A Box–Behnken design was employed to determine the optimal values for three extraction parameters: temperature (X1: 20°C–60°C), methanol concentration (X2: 60%–100%), and extraction time (X3: 30–90 min). The highest lignan contents were obtained at X1 = 44.24°C, X2 = 84.64%, and X3 = 53.63 min. To apply these experimental conditions to the actual experiment, the optimal conditions were slightly adjusted to X1 = 40°C, X2 = 80%, and X3 = 60 min. The predicted results closely matched the experimental results obtained using the modified optimal extraction conditions. The highest lignan content found in barley sprouts (85.930 μg/100 g), however, most grains exhibited relatively low concentrations of lignans. These findings provide valuable insights into the lignan content of grains and contribute to the generation of reliable data in this field.
... β-Glucan is a polysaccharide with a D-glucose unit linkage. Oat β-glucan is unique in that; it is composed of a group of linear polymers of glucose molecules linked by roughly 30% −(1-3) and 70% −(1-4) linkages [47]. Tese linkages are not arranged randomly, with (1-4) links appearing in groups of two to four and (1-3) links appearing singly [46]. ...
Oats (Avena sativa L.) are a popular functional cereal grain due to their numerous health benefits. This review article summarized the information on the chemical composition and phytonutrients of oats grown in different countries. It also reviewed recently developed fermented oat products to highlight their potential for human health. Oats have an interesting nutritional profile that includes high-quality protein, unsaturated fats, soluble fiber, polyphenolic compounds, and micronutrients. Oat grain has a unique protein composition, with globulins serving as the primary storage protein, in contrast to other cereals, where prolamins are the main storage proteins. Oats have the highest fat content of any cereal, with low saturated fatty acids and high essential unsaturated fatty acid content, which can help reduce the risk of cardiovascular diseases. Oats are a good source of soluble dietary fiber, particularly β-glucan, which has outstanding functional properties and is extremely important in human nutrition. β-Glucan has been shown to lower blood cholesterol and glucose absorption in the intestine, thereby preventing diseases such as cardiovascular injury, dyslipidemia, hypertension, inflammatory state, and type 2 diabetes. Oats also contain high concentration of antioxidant compounds. Avenanthramides, which are unique to oats, are powerful antioxidants with high antioxidative activity in humans. Recognizing the nutritional benefits of oats, oat-based fermented food products are gaining popularity as functional foods with high probiotic potential.
... 32,33 Oats are rich in a unique group of alkaloids first discovered in oats, namely avenanthramides and avenacosides A and B. 34 In addition, oat grains are rich in phenolic compounds, carotenoids, and phytosterols, including b-sitosterol, sitostanol, campesterol, and campestanol. 35 Rice bran is particularly rich in a unique group of phytochemicals, oryzanols, that are conjugates of ferulic acid esters of phytosterols and triterpenoids. 36 Various aspects affect the composition and bioavailability of phytochemicals in dietary cereals. ...
Cereal grains are the main dietary source of energy, carbohydrates, and plant proteins world-wide. Currently, only 41% of grains are used for human consumption, and up to 35% are used for animal feed. Cereals have been overlooked as a source of environmentally sustainable and healthy plant proteins and could play a major role in transitioning towards a more sustainable food system for healthy diets. Cereal plant proteins are of good nutritional quality, but lysine is often the limiting amino acid. When consumed as whole grains, cereals provide health-protecting components such as dietary fiber and phytochemicals. Shifting grain use from feed to traditional foods and conceptually new foods and ingredients could improve protein security and alleviate climate change. Rapid development of new grain-based food ingredients and use of grains in new food contexts, such as dairy replacements and meat analogues, could accelerate the transition. This review discusses recent developments and outlines future perspectives for cereal grain use.
... In this way, plant sources, have taken special interest among the population, especially oat; in Canada alone, its consumption has increased from 0.2 to 0.4 million tons in the last three years (USDA-FAS, 2020). Oat (Avena sativa L.) is the fifth most-cultivated cereal in the world (Guerrieri, 2018;FAO, 2019), and it is well-known as a source rich in bioactive compounds, including β-glucan, arabinoxylan, oligosaccharides, polyphenols, avenanthramides, indole-gramine alkaloids, flavonolignans, triterpenoid, saponins, sterols and tocols (Cui and Liu, 2014). ...
Oat (Avena sativa) is one of the most cultivated and consumed cereals worldwide. Recognized among cereals for its high protein content (12% to 24%), it makes it an excellent source of bioactive peptides, which could be modified during processes such as heating and gastrointestinal digestion (GID). This work aims to evaluate the impact of heat treatment on the proteolysis of oat proteins and on the evolution of antioxidant peptide release during in vitro static GID, in terms of comparative analysis between cooked oat protein concentrate (COPC) and non-heated oat protein concentrate (OPC) samples. The protein extraction method and cooking procedure used showed no detrimental effects on protein quality. After GID, the proportion of free amino acids/dipeptides (<0.2 kDa) reached >40% for both samples (OPC and COPC), thus producing peptides with low molecular weight and enhanced bioactivity. Furthermore, during GID, the amino acid profile showed an increase in essential, positively-charged, hydrophobic and aromatic amino acids. At the end of GID, the reducing power of OPC and COPC increased >0.3 and 8-fold, respectively, in comparison to the non-digested samples; while ABTS•+ and DPPH• showed a >20-fold increase. Fe2+ chelating capacity of OPC and COPC was enhanced >4 times; similarly, Cu2+ chelation showed a >19-fold enhancement for OPC and >10 for COPC. β-carotene bleaching activity was improved 0.8 times in OPC and >9 times in COPC; the oxygen radical antioxidant capacity assay increased 2 times in OPC and >4.7 times in COPC, respectively. This study suggests that OPC after cooking and GID positively influenced the nutritional and bioactive properties of oat peptides. Thus, COPC could be used as a functional food ingredient with health-promoting effects, as hydrothermal treatment is frequently used for this type of cereals.
Pre-harvest glyphosate is applied to cereal grains to control weed growth. However, it has been claimed that oat (Avena sativa L.) composition is affected by pre-harvest glyphosate application. The research was conducted to evaluate differences in properties of β-glucan in grains of pre-harvest glyphosate treated versus untreated oat plants. Two oat cultivars (Rockford and Souris) were grown at Minot and Prosper, ND, in 2015, and glyphosate was sprayed during the soft dough stage, hard dough stage, or not applied. β-glucan viscosity was not significantly (p > 0.05) affected by treatment at soft dough (1082 cP) or mature (1166 cP) stages compared with untreated (1150 cP) controls. Applying glyphosate at the soft dough stage significantly (p < 0.05) reduced the content and solubility of the β-glucan versus untreated samples. β-glucan content and solubility in oat treated at soft dough were 4.35% and 52.1%, respectively, while in untreated samples were 4.65% and 60.6%, respectively. Treatment at soft dough and hard dough stages significantly (p < 0.05) increased weight average molecular weight (Mw) of the high molecular weight fraction of soluble β-glucan (4.4 × 10⁶ and 3.8 × 10⁶, respectively), compared with untreated controls (3.5 × 10⁶). The Mw of the low molecular weight fraction of soluble β-glucan fraction significantly (p < 0.05) increased at soft and hard dough treatments (5.5 × 10⁵ and 3.3 × 10⁵, respectively), versus untreated samples (3.0 × 10⁵). Therefore, glyphosate can be applied when the grain has reached physiological maturity or thereafter.
This article presents an overview of the recent advances into the health promoting potentials of oat β‐glucan. Oat β‐glucan (OβG) consists mainly of the linear polysaccharide (1→3), (1→4)‐β‐D‐glucan and is often called β‐glucan. This soluble oat fiber is able to attenuate blood postprandial glycemic and insulinemic responses, to lower blood total cholesterol and low‐density lipoprotein (LDL) cholesterol, and to improve high‐density lipoprotein (HDL) cholesterol and blood lipid profiles as well as to maintain body weight. Thus, OβG intake is beneficial in the prevention, treatment, and control of diabetes and cardiovascular diseases. In addition, OβG can stimulate immune functions by activating monocytes/macrophages and increasing the amounts of immunoglobulin, NK cells, killer T‐cells, and so on, which will improve resistance to cancer and infectious and parasitic diseases, as well as increase biological therapies and their prevention. All these health benefits of OβG may be explained by its physicochemical properties (such as viscosity, molecular weight) which can be affected by extraction methods and its behavior in gastrointestinal tract. Articles documenting these health benefits and effects are reviewed.
π π π electrons are delocalised over the entire length of the polyene chain is responsible for the molecular shape, chemical and physical reactivity and the antioxidant properties of carotenoids. It is sensitive to heat, light and oxygen. Enzymatic and non-enzymatic oxidation is the major cause of carotenoid destruction during processing and storage of food. Bio- availability of carotenoids from different food requires disruption of the food matrices. Thermal treatment and freezing increases the extractability of β β β β-carotene from the food matrices. Ripening is accompanied by increased carotenoid biosynthesis.
Context Epidemiological studies of men suggest that dietary
fiber intake protects against coronary heart disease (CHD), but data on
this association in women are sparse.Objective To examine the association between long-term intake of
total dietary fiber as well as fiber from different sources and risk of
CHD in women.Design and Setting The Nurses' Health Study, a large, prospective
cohort study of US women followed up for 10 years from 1984. Dietary
data were collected in 1984, 1986, and 1990, using a validated
semiquantitative food frequency questionnaire.Participants A total of 68,782 women aged 37 to 64 years
without previously diagnosed angina, myocardial infarction (MI),
stroke, cancer, hypercholesterolemia, or diabetes at baseline.Main Outcome Measure Incidence of acute MI or death due to CHD by
amount of fiber intake.Results Response rate averaged 80% to 90% during the
10-year follow-up. We documented 591 major CHD events (429 nonfatal MIs
and 162 CHD deaths). The age-adjusted relative risk (RR) for major CHD
events was 0.53 (95% confidence interval [CI], 0.40-0.69) for women
in the highest quintile of total dietary fiber intake (median, 22.9
g/d) compared with women in the lowest quintile (median, 11.5 g/d).
After controlling for age, cardiovascular risk factors, dietary
factors, and multivitamin supplement use, the RR was 0.77 (95% CI,
0.57-1.04). For a 10-g/d increase in total fiber intake (the difference
between the lowest and highest quintiles), the multivariate RR of total
CHD events was 0.81 (95% CI, 0.66-0.99). Among different sources of
dietary fiber (eg, cereal, vegetables, fruit), only cereal fiber was
strongly associated with a reduced risk of CHD (multivariate RR, 0.63;
95% CI, 0.49-0.81 for each 5-g/d increase in cereal fiber).Conclusions Our findings in women support the hypothesis that
higher fiber intake, particularly from cereal sources, reduces the risk
of CHD.
Phytosterols are hypocholesterolemic. Like corn fiber oil, the lipid extracts of certain cereal by-products may be rich sources
of these health-promoting compounds. The objective of this research was to examine the phytosterol content and composition
of various cereal by-products. Total lipids in rice bran, wheat bran, wheat germ, durum wheat (bran and germ mixture), oat
bran, oat hull, and corn fine fiber were extracted, and the sterol profiles of the extracted lipids were analyzed by GC. Rice
bran contained the most lipids (22.2%), followed by wheat germ, durum wheat, oat bran, wheat bran, and oat hull; corn fine
fiber contained the least amount of lipids (1.7%). Sitosterol, campesterol, and stigmasterol were the major phytosterols in
these lipid extracts, whereas brassicasterol was detected only in wheat samples. Rice bran oil contained considerable amounts
of cycloartenol and 24-methylenecycloartanol, which were unique to these samples. Total sterol concentrations in extracted
lipids were similar for rice bran, wheat bran, wheat germ, and durum wheat (21.3–15.1 mg/g), but they were very low in oat
bran lipids and oat hull lipids (3.4 and 8.2 mg/g, respectively). Corn fine fiber lipids contained the highest amount of sterols
(48.3 mg/g). Rice bran appears to be the best source of phytosterols, with the highest oil content and high concentration
of sterols.
The strong male predominance in esophageal and gastroesophageal junctional adenocarcinoma remains unexplained. Sex hormonal influence has been suggested, but not proven. A protective role of dietary phytoestrogen lignans was hypothesized.
A Swedish nationwide population-based case-control study was conducted in 1995-1997, including 181 cases of esophageal adenocarcinoma, 255 cases of gastroesophageal junctional adenocarcinoma, 158 cases of esophageal squamous cell carcinoma, and 806 control subjects. Data on various exposures, including dietary data, were collected through personal interviews and questionnaires. Dietary intake of lignans was assessed using a food frequency questionnaire and categorized into quartiles based on the consumption among the control participants. Unconditional logistic regression was used to calculate odds ratios (ORs) with 95 % confidence intervals (CIs), including adjustment for all established risk factors.
Participants in the highest quartile of intake of lignans compared with the lowest quartile were at a decreased risk of esophageal adenocarcinoma (OR, 0.65; 95 % CI, 0.38-1.12; p for trend =0.03), gastroesophageal junctional adenocarcinoma (OR, 0.37; 95 % CI, 0.23-0.58; p for trend <0.0001), and these adenocarcinomas combined (OR, 0.45; 95 % CI, 0.31-0.67; p for trend <0.0001). No clear associations were found between lignan intake and risk of esophageal squamous cell carcinoma.
This population-based study indicates that a high dietary intake of lignans decreases the risk of adenocarcinoma of the esophagus and gastroesophageal junction.
Avenanthramides are a group of alkaloids that consist of an anthranilic acid derivative linked to a hydroxycinnamic acid derivative by a pseudo peptide bond, which are constituents of oat (Avena sativa L.) grain. The three most abundant avenanthramides, N-(4′-hydroxy-3′-methoxycinnamoyl)-5-hydroxyanthranilic acid (Bf), N-(4′-hydroxycinnamoyl)-5-hydroxyanthranilic acid (Bp), and N-(3′,4′-dihydroxycinnamoyl)-5-hydroxyanthranilic acid (Bc), were synthesized and purified. These were tested for antioxidant activity using two in vitro systems: inhibition of β-carotene bleaching and reaction with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Each avenanthramide displayed antioxidant activity in both systems. Bc had greater activity than Bp and Bf. Bc was nearly as active as the standard synthetic antioxidant, butylated hydroxytoluene (BHT) in the β-carotene system. In the DPPH system, Bc and Bf were more active than 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox®). The relative activities of the avenanthramides corresponded to those determined for their component hydroxycinnamic acid moieties using an aqueous DPPH system or in a lipophilic system that measured the autoxidation of methyl linoleate.
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.
Oat milling fractions were examined for concentrations of total phenolics, tocols, and phenolic acids and in vitro antioxidant activity to determine their potential as dietary antioxidants. Methanolic extracts of pearling fractions, flour and aspirations from flaking, and trichomes had high, intermediate, and low antioxidant activities, respectively, evaluated by the beta-carotene bleaching method. Pearling fractions were also highest in total phenolics and tocols. p-Hydroxybenzoic acid, vanillic acid, caffeic acid, vanillin, p-coumaric acid, and ferulic acid were identified and quantified by HPLC. Three avenanthramides and an unidentified ferulate derivative were also detected. Total phenolic content was significantly correlated with antioxidant activity, and regression equations that predicted antioxidant activity from phenolic and tocol concentrations were calculated. Antioxidant activity, evaluated by beta-carotene bleaching, was correlated with measures of oxygen radical absorbance capacity and low-density lipoprotein oxidation. These data indicate a potential for oat products, especially those enriched in outer layers of the groat, to contribute to dietary intakes of antioxidant phytonutrients.
Elevated total and low-density lipoprotein (LDL) cholesterol levels are considered major risk factors for cardiovascular disease. Oat β-glucan, a soluble dietary fiber that is found in the endosperm cell walls of oats, has generated considerable interest due to its cholesterol-lowering properties. The United States Food and Drug Administration (FDA) approved a health claim for β-glucan soluble fiber from oats for reducing plasma cholesterol levels and risk of heart disease in 1997. Similarly, in 2004 the United Kingdom Joint Health Claims Initiative (JHCI) allowed a cholesterol-lowering health claim for oat β-glucan. The present review aims to investigate if results from more recent studies are consistent with the original conclusions reached by the FDA and JHCI. Results of this analysis show that studies conducted during the past 13 years support the suggestion that intake of oat β-glucan at daily doses of at least 3 g may reduce plasma total and low-density lipoprotein (LDL) cholesterol levels by 5-10% in normocholesterolemic or hypercholesterolemic subjects. Studies described herein have shown that, on average, oat consumption is associated with 5% and 7% reductions in total and LDL cholesterol levels, respectively. Significant scientific agreement continues to support a relationship between oat β-glucan and blood cholesterol levels, with newer data being consistent with earlier conclusions made by the FDA and JHCI.
Consumption of wholegrain (WG) products may protect against colon and rectal cancer.
The associations between total and individual WG product consumption and colon and rectal cancer risk were prospectively examined using data on 461 incident cases of colon cancer and 283 incident cases of rectal cancer that developed during 10.6 years (median) of follow-up among 26 630 men and 29 189 women taking part in the Diet, Cancer and Health cohort. Incidence rate ratios (IRRs) of colon and rectal cancer related to total or individual WG product intake were calculated using Cox regression.
Higher WG product intake was associated with lower risk of colon cancer and rectal cancer in men. The adjusted IRR (95% CI) was 0.85 (0.77-0.94) for colon cancer and 0.90 (0.80-1.01) for rectal cancer per daily 50 g increment in intake. For colon cancer the association was confined to intake of WG bread in particular. No consistent associations between total or individual WG product consumption and colon or rectal cancer risk were observed in women.
The findings suggest that higher total WG product intake is associated with a lower risk of colon and perhaps rectal cancer in men, but not in women.
Consumption of 3 g oat β-glucan/d is considered sufficient to lower serum LDL cholesterol, but some studies have shown no effect. LDL cholesterol lowering by oat β-glucan may depend on viscosity, which is controlled by the molecular weight (MW) and amount of oat β-glucan solubilized in the intestine (C).
Our 2 primary objectives were to determine whether consumption of 3 g high-MW oat β-glucan/d would reduce LDL cholesterol and whether LDL cholesterol lowering was related to the log(MW × C) of oat β-glucan.
In a double-blind, parallel-design, multicenter clinical trial, subjects with LDL cholesterol ≥3.0 and ≤5.0 mmol/L (n = 786 screened, n = 400 ineligible, n = 19 refused, n = 367 enrolled, and n = 345 completed) were randomly assigned to receive cereal containing wheat fiber (n = 87) or 3 g high-MW (2,210,000 g/mol, n = 86), 4 g medium-MW (850,000 g/mol, n = 67), 3 g medium-MW (530,000 g/mol, n = 64), or 4 g low-MW (210,000 g/mol, n = 63) oat β-glucan/d (divided doses, twice daily) for 4 wk.
LDL cholesterol was significantly less with 3 g high-MW, 4 g medium-MW, and 3 g medium-MW oat β-glucan cereals than with the wheat-fiber cereal by 0.21 (5.5%; 95% CI: -0.11, -0.30; P = 0.002), 0.26 (6.5%; 95% CI: -0.14, -0.37; P = 0.0007), and 0.19 (4.7%; 95% CI: -0.08, -0.30; P = 0.01) mmol/L, respectively. However, the effect of 4 g low-MW oat β-glucan/d (0.10 mmol/L) was not significant (2.3%; 95% CI: 0.02, -0.20). By analysis of covariance, log(MW × C) was a significant determinant of LDL cholesterol (P = 0.003). Treatment effects were not significantly influenced by age, sex, study center, or baseline LDL cholesterol.
The physicochemical properties of oat β-glucan should be considered when assessing the cholesterol-lowering ability of oat-containing products; an extruded breakfast cereal containing 3 g oat β-glucan/d with a high-MW (2,210,000 g/mol) or a medium-MW (530,000 g/mol) lowered LDL cholesterol similarly by ≈0.2 mmol/L (5%), but efficacy was reduced by 50% when MW was reduced to 210,000 g/mol. This trial was registered at www.clinicaltrials.gov as NCT00981981.
Results of epidemiological studies of dietary fiber and colorectal cancer risk have not been consistent, possibly because of attenuation of associations due to measurement error in dietary exposure ascertainment.
To examine the association between dietary fiber intake and colorectal cancer risk, we conducted a prospective case-control study nested within seven UK cohort studies, which included 579 case patients who developed incident colorectal cancer and 1996 matched control subjects. We used standardized dietary data obtained from 4- to 7-day food diaries that were completed by all participants to calculate the odds ratios for colorectal, colon, and rectal cancers with the use of conditional logistic regression models that adjusted for relevant covariates. We also calculated odds ratios for colorectal cancer by using dietary data obtained from food-frequency questionnaires that were completed by most participants. All statistical tests were two-sided.
Intakes of absolute fiber and of fiber intake density, ascertained by food diaries, were statistically significantly inversely associated with the risks of colorectal and colon cancers in both age-adjusted models and multivariable models that adjusted for age; anthropomorphic and socioeconomic factors; and dietary intakes of folate, alcohol, and energy. For example, the multivariable-adjusted odds ratio of colorectal cancer for highest vs the lowest quintile of fiber intake density was 0.66 (95% confidence interval = 0.45 to 0.96). However, no statistically significant association was observed when the same analysis was conducted using dietary data obtained by food-frequency questionnaire (multivariable odds ratio = 0.88, 95% confidence interval = 0.57 to 1.36).
Intake of dietary fiber is inversely associated with colorectal cancer risk. Methodological differences (ie, study design, dietary assessment instruments, definition of fiber) may account for the lack of convincing evidence for the inverse association between fiber intake and colorectal cancer risk in some previous studies.
Diets rich in flavonoids may reduce the risk of developing colorectal cancer. Flavonoids are widely distributed in foods of plant origin, though in the UK tea is the main dietary source. Our objective was to evaluate any independent associations of total dietary and non-tea intake of four flavonoid subclasses and the risk of developing colorectal cancer in a tea-drinking population with a high colorectal cancer incidence. A population-based case-control study (264 cases with histologically confirmed incident colorectal cancer and 408 controls) was carried out. Dietary data gathered by FFQ were used to calculate flavonoid intake. Adjusted OR and 95 % CI were estimated by logistic regression. No linear association between risk of developing colorectal cancer and total dietary flavonol, procyanidin, flavon-3-ol or flavanone intakes was found, but non-tea flavonol intake was inversely associated with colorectal cancer risk (OR 0.6; 95 % CI 0.4, 1.0). Stratification by site of cancer and assessment of individual flavonols showed a reduced risk of developing colon but not rectal cancer with increasing non-tea quercetin intake (OR 0.5; 95 % CI 0.3, 0.8; P(trend) < 0.01). We concluded that flavonols, specifically quercetin, obtained from non-tea components of the diet may be linked with reduced risk of developing colon cancer.
Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as beta-glucans. beta-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, beta-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by beta-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1-->3 linear beta-glycosidic chain of beta-glucans cannot be digested. Most beta-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small beta-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, beta-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate beta-glucans is essential if we wish to investigate the effects of beta-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified beta-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of beta-glucans or beta-glucans containing compounds.
Phytosterols (plant sterols and stanols) are well known for their LDL-cholesterol (LDL-C)-lowering effect. A meta-analysis of randomized controlled trials in adults was performed to establish a continuous dose-response relationship that would allow predicting the LDL-C-lowering efficacy of different phytosterol doses. Eighty-four trials including 141 trial arms were included. A nonlinear equation comprising 2 parameters (the maximal LDL-C lowering and an incremental dose step) was used to describe the dose-response curve. The overall pooled absolute (mmol/L) and relative (%) LDL-C-lowering effects of phytosterols were also assessed with a random effects model. The pooled LDL-C reduction was 0.34 mmol/L (95% CI: -0.36, -0.31) or 8.8% (95% CI: -9.4, -8.3) for a mean daily dose of 2.15 g phytosterols. The impacts of subject baseline characteristics, food formats, type of phytosterols, and study quality on the continuous dose-response curve were determined by regression or subgroup analyses. Higher baseline LDL-C concentrations resulted in greater absolute LDL-C reductions. No significant differences were found between dose-response curves established for plant sterols vs. stanols, fat-based vs. non fat-based food formats and dairy vs. nondairy foods. A larger effect was observed with solid foods than with liquid foods only at high phytosterol doses (>2 g/d). There was a strong tendency (P = 0.054) towards a slightly lower efficacy of single vs. multiple daily intakes of phytosterols. In conclusion, the dose-dependent LDL-C-lowering efficacy of phytosterols incorporated in various food formats was confirmed and equations of the continuous relationship were established to predict the effect of a given phytosterol dose. Further investigations are warranted to investigate the impact of solid vs. liquid food formats and frequency of intake on phytosterol efficacy.
Clinical trials using antihyperglycemic medications to improve glycemic control have not demonstrated the anticipated cardiovascular benefits. Low-glycemic index diets may improve both glycemic control and cardiovascular risk factors for patients with type 2 diabetes but debate over their effectiveness continues due to trial limitations.
To test the effects of low-glycemic index diets on glycemic control and cardiovascular risk factors in patients with type 2 diabetes.
A randomized, parallel study design at a Canadian university hospital research center of 210 participants with type 2 diabetes treated with antihyperglycemic medications who were recruited by newspaper advertisement and randomly assigned to receive 1 of 2 diet treatments each for 6 months between September 16, 2004, and May 22, 2007.
High-cereal fiber or low-glycemic index dietary advice.
Absolute change in glycated hemoglobin A(1c) (HbA(1c)), with fasting blood glucose and cardiovascular disease risk factors as secondary measures.
In the intention-to-treat analysis, HbA(1c) decreased by -0.18% absolute HbA(1c) units (95% confidence interval [CI], -0.29% to -0.07%) in the high-cereal fiber diet compared with -0.50% absolute HbA(1c) units (95% CI, -0.61% to -0.39%) in the low-glycemic index diet (P < .001). There was also an increase of high-density lipoprotein cholesterol in the low-glycemic index diet by 1.7 mg/dL (95% CI, 0.8-2.6 mg/dL) compared with a decrease of high-density lipoprotein cholesterol by -0.2 mg/dL (95% CI, -0.9 to 0.5 mg/dL) in the high-cereal fiber diet (P = .005). The reduction in dietary glycemic index related positively to the reduction in HbA(1c) concentration (r = 0.35, P < .001) and negatively to the increase in high-density lipoprotein cholesterol (r = -0.19, P = .009).
In patients with type 2 diabetes, 6-month treatment with a low-glycemic index diet resulted in moderately lower HbA(1c) levels compared with a high-cereal fiber diet. Trial Registration clinicaltrials.gov identifier: NCT00438698.
Background: Plant lignans are converted to enterolignans that have antioxidant and weak estrogen-like activities, and therefore they may lower cardiovascular disease and cancer risks.
Objective: We investigated whether the intakes of 4 plant lignans (lariciresinol, pinoresinol, secoisolariciresinol, and matairesinol) were inversely associated with coronary heart disease (CHD), cardiovascular diseases (CVD), cancer, and all-cause mortality.
Design: The Zutphen Elderly Study is a prospective cohort study in which 570 men aged 64–84 y were followed for 15 y. We recently developed a database and used it to estimate the dietary intakes of 4 plant lignans. Lignan intake was related to mortality with the use of Cox proportional hazards analysis.
Results: The median total lignan intake in 1985 was 977 μg/d. Tea, vegetables, bread, coffee, fruit, and wine were the major sources of lignan. The total lignan intake was not related to mortality. However, the intake of matairesinol was inversely associated with CHD, CVD, and all-cause mortality (P ≤ 0.05 for all) and cancer (P = 0.06). Multivariate-adjusted rate ratios (95% CI) per 1-SD increase in intake were 0.72 (0.53, 0.98) for CHD, 0.83 (0.69, 1.00) for CVD, 0.86 (0.76, 0.97) for all-cause mortality, and 0.81 (0.65, 1.00) for cancer.
Conclusions: Total lignan intake was not associated with mortality. The intake of matairesinol was inversely associated with mortality due to CHD, CVD, cancer, and all causes. We cannot exclude the possibility that the inverse association between matairesinol intake and mortality is due to an associated factor, such as wine consumption.
A prudent diet, physical exercise, and weight loss represent the main components of the lifestyle critical to prevent diabetes in susceptible individuals.
Estimating flavonoid intake is a first step toward documenting the protective effects of flavonoids against risk of chronic diseases. Although flavonoids are important dietary sources of antioxidants, insufficient data on the comprehensive food composition of flavonoids have delayed the assessment of dietary intake in a population. We aimed to estimate the dietary flavonoid intake in U.S. adults and its sociodemographic subgroups and to document major dietary sources of flavonoids. We expanded the recently released USDA Flavonoid Database to increase its correspondence with the 24-h dietary recall (DR) of the NHANES 1999–2002. We systematically assigned a particular food code to all foods that were prepared or processed similarly. This expanded database included 87% of fruits and fruit juices, 86% of vegetables, 75% of legumes, and, overall, 45% of all foods reported by the 24-h DR of the NHANES 1999–2002. Estimated mean daily total flavonoid intake, 189.7 mg/d, was mainly from flavan-3-ols (83.5%), followed by flavanones (7.6%), flavonols (6.8%), anthocyanidins (1.6%), flavones (0.8%), and isoflavones (0.6%). The flavonoid density of diets increased with age (P < 0.001) and income (P < 0.05). It was higher in women (P < 0.001), Caucasians (P < 0.001), and vitamin supplement users (P < 0.001) and lower in adults with high levels of nonleisure time physical activity (P < 0.01) compared with their counterparts. The greatest daily mean intake of flavonoids was from the following foods: tea (157 mg), citrus fruit juices (8 mg), wine (4 mg), and citrus fruits (3 mg). The proposed relation between flavonoid intake and the prevention of chronic diseases needs further investigation using the estimates introduced in this study.
Lignans are present in a wide range of foods consumed daily in the Western world such as flaxseed and other seeds, as well as vegetables, fruits and beverages such as coffee, tea and wine. Secoisolariciresinol diglucoside, a plant lignan, is metabolised to enterodiol and, then, to enterolactone. Matairesinol, another plant lignan, is also metabolised to enterolactone. Other dietary enterolignan precursors include lariciresinol, pinoresinol, medioresinol, syringaresinol, arctigenin and sesamin. Enterolignan-producing bacteria are common and accordingly enterolignans can be detected in the blood of most individuals; therefore, inter-individual differences in cell densities of the aforementioned bacteria may explain inter-individual differences in concentrations of enterolignan in blood. Research into the role of lignans in breast, colon and prostate cancer has generally shown they exert beneficial effects, although there are also some inconclusive studies or others that report negative effects. There are several possible mechanistic explanations for the observed bioactivities, including involvement in hormonal metabolism or availability, angiogenesis, anti-oxidation and gene suppression. Moreover, physiologically relevant concentrations of enterolignan have been shown to lead to “in vitro” and “in vivo” activation of oestrogen receptors.
Using a combination GLC-mass spectrometer the presence of saturated C27 (I), C28 (II) and C29 (III) sterols together with the corresponding Δ5- (IV–VI) and Δ7-monounsaturated (VII–IX) sterols, both 24-methylene-Δ5- (X) and 24-methylene-Δ7-3β-ol (XI), the corresponding 24-ethylidene compounds (XII–XIII) and stigmasterol (XIV) in oat seed has been demonstrated.
Purpose
To review the evidence from high quality human intervention studies that reported links between oat consumption and cardiovascular disease (CVD) risk factors.
Design/methodology/approach
Using Medline, a search was made for all randomized controlled trials published between 1990 and 2008 that met defined inclusion criteria. Studies had a minimum duration of 14 days, used oat products rather than purified extracts, and included plasma lipid levels as outcome variables.
Findings
A total of 21 eligible studies were located 13 of which reported significant reductions in total cholesterol when oats were consumed, while 14 reported significant reductions in low‐density lipoprotein cholesterol. A few studies found increases in high‐density lipoprotein cholesterol and more favourable cholesterol ratios when oats were consumed.
Research limitations/implications
It was not possible to analyse differences in response between health and “at risk” subjects. A meta‐analysis would be a useful step forward, as would research on the long‐term impact of oats on body weight.
Practical implications
Intakes of oats in successful intervention studies were impractical for most consumers. However, expert bodies base approved health claims on an achievable 3 g β‐glucan per day. Additional research on portion sizes for commercially‐available foods would increase consumer awareness of how to access the cholesterol‐lowering benefits of oats. Effective portion sizes may differ by gender, age and CVD risk.
Originality/value
This review provides further evidence that regular oat consumption is an effective dietary strategy for helping to attenuate CVD risk and sets this within the context of claims for food stuffs.
Objectives.
—To test the a priori hypothesis that consumption of oats will lower the blood total cholesterol level and to assess modifiers and confounders of this association.
Data Sources.
—A computerized literature (MEDLINE) search and the Quaker Oats Co identified published and unpublished trials as of March 1991. Raw data were requested for all trials.
Study Selection.
—Trials were included in summary effect size estimates if they were randomized and controlled, if a formal assessment of diet and body weight changes occurred, and, if raw data were not received, if there was enough information in the published report to perform calculations.
Data Synthesis.
—Twenty trials were identified. Using the methods of DerSimonian and Laird, a summary effect size for change in blood total cholesterol level of -0.13 mmol/L (-5.9 mg/dL) (95% confidence interval [Cl], -0.19 to -0.017 mmol/L [-8.4 to -3.3 mg/dL]) was calculated for the 10 trials meeting the inclusion criteria. The summary effect size for trials using wheat control groups was -0.11 mmol/L (-4.4 mg/dL) (95% Cl, -0.21 to -0.01 mmol/L [-8.3 to -0.38 mg/dL]). Calculation of Keys scores demonstrated that substituting carbohydrates for dietary fats and cholesterol did not account for the majority of blood cholesterol reduction. Larger reductions were seen in trials in which subjects had initially higher blood cholesterol levels (≥5.9 mmol/L [≥229 mg/dL]), particularly when a dose of 3 g or more of soluble fiber was employed.
Conclusion.
—This analysis supports the hypothesis that incorporating oat products into the diet causes a modest reduction in blood cholesterol level.(JAMA. 1992;267:3317-3325)
Low molecular weight phenolic compounds present in heat processed oats (Avena sativaL) were analysed. The oat grains were of three varieties (Kapp, Mustang and Svea), stored at different relative humidities (30, 55 or 80%) and periods (3·5 or 15·5 months) and processed with or without hulls. Eleven UV-absorbing compounds detected by High Performance Liquid Chromatography were subjected to univariate and multivariate statistical analysis. The selected compounds included caffeic acid,p-coumaric acid, ferulic acid, vanillic acid,p-hydroxybenzaldehyde, vanillin, coniferyl alcohol, three avenanthramides and one unidentified substance. The levels of vanillic acid, vanillin and, especially,p-coumaric acid,p-hydroxybenzaldehyde and coniferyl alcohol increased significantly in samples processed with hulls, but not in samples processed without hulls. Ferulic acid increased in both processes, while caffeic acid and the avenanthramides were found to decrease during processing. Storage of unprocessed samples for 1 year generally increased the levels of phenolic acids and aldehydes. For the phenolic acids (except ferulic acid), this increase was most pronounced after storage at high relative humidity (80%). The avenanthramides were present at their highest levels in Mustang, caffeic acid in Svea and Mustang, the unidentified compound in Svea, while all the other compounds studied were present predominantly in the variety Kapp.
The total phenolic acid content of wheat, rice, and oat flours ranged from 71 to 87 ppm while corn flour contained 309 ppm and potato flour 410 ppm. Cis- and trans-ferulic and -p-coumaric acids and syringic acid were the principal phenolic compounds in the free acid or soluble ester fractions of the cereal flours. Alkaline hydrolysis of the insoluble residue of the cereals released the major proportion of phenolic acids, principally trans-ferulic acid. Free chlorogenic acid was the principal phenolic acid in potato flour, and a significant proportion of caffeic acid was released on hydrolysis of soluble esters. Wheat flour which had been stored for 6 months contained only 26 ppm of total phenolic acids, primarily in the bound form.
Fractionation of methanolic extracts of oat groats and hulls by anion-exchange chromatography revealed the presence of a series of anionic, substituted cinnamic acid conjugates, trivially named avenanthramides. Two-dimensional thin-layer chromatography (TLC) showed groat extracts contain more than 25 distinct avenanthramides, while hull extracts contained about 20. Some 15 were common to both groat and hull preparations. The substances were purified by repeated column chromatography on Sephadex LH-20, using TLC to monitor purity, and crystallized from aqueous acetone. The complete structures of 10 avenanthramides have been elucidated using 1H and 13C nuclear magnetic resonance (NMR), mass spectroscopy (MS), ultraviolet absorption spectroscopy (UV), and hydrolytic techniques and confirmed by total synthesis. The physicochemical properties, potential biological activity, and distribution within the oat grain are discussed.
The total and individual sterol content in 21 oat samples (seven cultivars grown at three different locations in Sweden) were analysed by gas chromatography after acid hydrolysis. The total sterol content in these oat cultivars varied between 350–491 µg g−1 of dry weight of kernel. The most abundant phytosterol was β-sitosterol (237–321 µg g−1) followed by campesterol (32–46 µg g−1), Δ5-avenasterol (15–47 µg g−1) and stigmasterol (11–21 µg g−1). There was a statistically significant difference in total sterol content between cultivars (p < 0.05) but no effect was found for cultivation location. Furthermore when contents of Δ5-avenasterol in hexane-extracted oat oil and acid-hydrolysed oat samples were compared, it was noticed that the content of Δ5-avenasterol was lowered due to acid hydrolysis. © 1999 Society of Chemical Industry
This case–cohort study examined the association between plasma enterolactone concentration and incidence of colon and rectal
cancer in the Diet, Cancer and Health cohort, which enrolled 57,053 participants aged 50–64. Information about diet and lifestyle
was obtained by questionnaire, and data on prescriptions of antibiotics were obtained from the Danish Prescription Registry.
Cases diagnosed during 5.9years of follow-up and a randomly selected sample of the cohort had a plasma sample analyzed for
enterolactone by time-resolved fluoro-immuno assay. Associations were analyzed by Cox proportional hazards model. A total
of 244 colon cancer cases, 137 rectal cancer cases, and 370 sub-cohort members were included in the statistical analyses.
For each doubling in enterolactone concentration, we found lower risk of colon cancer among women [IRR (95% CI)=0.76 (0.60–0.96)]
and a tendency toward lower risk of rectal cancer [IRR (95% CI)=0.83 (0.60–1.14)]. Among men, a doubling in enterolactone
tended to be associated with higher risk of colon cancer [IRR (95% CI)=1.09 (0.89–1.34)] and was associated with statistically
significantly higher risk of rectal cancer [IRR (95% CI)=1.74 (1.25–2.44)]. Exclusion of antibiotics users strengthened
the results slightly. In conclusion, with higher enterolactone levels, we found lower risk of colon cancer among women and
higher risk of rectal cancer among men.
β-glucan was isolated from oat bran in a highly purified form. The bran was characterized for its contents of dietary fiber, β-glucan, fat and protein. The isolated β-glucan was free of protein and contained only glucose in GC sugar analysis. Two types of β-glucan were obtained with different solubilities. Their molar masses were 1.6 million for the less soluble and 1.1 million for the more readily soluble type. No structural differences were found. The two-dimensional correlation NMR spectrum of the isolated β-glucan showed that the glucose units are joined with 1,3- and 1,4-linkages only. The oligosaccharides produced by the action of a specific enzyme, lichenase, were analyzed by HPLC and capillary zone electrophoresis. The major products are 32-β-d-glucosyl cellobiose (trisaccharide) and 33-β-d-glucosyl cellotriose (tetrasaccharide), which account for 95% of the whole. Also, 34-β-d-glucosyl cellotetraose (pentasaccharide) and other oligosaccharides with degree of polymerization (DP) higher than 5 were detected as minor components.
Oat (Avena sativa L.) is a source of many compounds that exhibit antioxidant activity. Vitamin E (tocols), phytic acid, phenolic compounds, and avenanthramides are the most abundant antioxidants in oat, and flavonoids and sterols are also present. These antioxidants are concentrated in the outer layers of the kernel. Several in vitro tests have been used to evaluate antioxidant activity of oat extracts. A few examples show that an oat-containing diet boosted the antioxidant capacity of serum or meat in animals. Avenanthramides may be a plant defense response, as these compounds are induced in oat leaves by rust spores or elicitors. Antioxidants function in helping to maintain the stability of processed oat products, and oat can stabilise oils and fats against rancidity. Possible future research should be aimed at increasing antioxidants by plant breeding and through a nutritional genomics approach. Additionally, we need to acquire knowledge about the bioavailability and function of antioxidants in human and animal systems. Methods for fractionation of oat to produce antioxidant co-products along with other high-value components should also be studied.
Oat β-glucan, present in oat bran in greater concentrations than in the whole oat groat, is mainly composed of β-(1 → 3)-linked cellotriosyl and cellotetraosyl units, present at 52 and 34% by weight of the molecule, respectively. The remaining structure consits of β-(1 → 3)-linked blocks composed of four or more consecutive β-(1 → 4)-linked d-glucopyranosyl units. Size-exclusion chromatography indicated a molecular weight for oat β-glucan of 2–3 × 106. This was significantly reduced during digestion in the small intestine of rats and chicks. In healthy human volunteers, oat β-glucan reduced the postprandial glucose response to an oral glucose load similarly to guar gum. The effectiveness of oat β-glucan was proportional to the logarithm of the viscosity of the solution fed.
In addition to the well-known effects of reducing blood cholesterol and affecting glycaemic response, dietary fibre of oat bran has been shown to have numerous other physiological effects. It delays gastric emptying, diminishes absorption of nutrients, affects the motility in the small bowel, and prolongs satiety after the meal. In the large bowel, soluble dietary fibre increases the fermentation activity, especially production of butyric acid, enhances growth and colonisation of some probiotic bacterial strains, increases production of microbial mass and thereby aids the removal of nitrogen via faeces. It also increases wet weight of stools, thereby alleviating constipation. Short-chain fatty acids formed enhance cell proliferation of the colonic mucosa. According to the present view, this reduces the risk of colon cancer. In addition to the effects of the viscosity of the intestinal contents and colon fermentation, the physiological effects are in part mediated via insulin and gastrointestinal hormone secretion. Papers documenting these effects are reviewed.
Phytochemicals and antioxidants in whole grains have not received as much attention as the phytochemicals in fruits and vegetables although the increased consumption of whole grains and whole grain products has been associated with reduced risk of developing chronic diseases such as cardiovascular disease, type 2 diabetes, some cancers and all-cause mortality. Recent research has shown that the total phytochemical content and antioxidant activity of whole grains have been commonly underestimated in the literature, and that whole grains contain more phytochemicals than was previously reported. Most whole grain phenolics are in bound form, 85% in corn, 76% in wheat, and 75% in oats. In addition, whole grains contain unique phytochemicals that complement those in fruits and vegetables when consumed together. The beneficial effects associated with whole grain consumption are in part due to the existence of the unique phytochemicals of whole grains. The majority of phytochemicals of whole grains that are beneficial for health are present in the bran/germ fraction. In whole wheat flour, the bran/germ fraction contributed 83% of total phenolic content, 79% of total flavonoid content, 78% of total zeaxanthin, 51% of total lutein, and 42% of total β-cryptoxanthin. The bran/germ fraction of whole wheat may therefore impart greater health benefits when consumed as part of a diet, and help reduce the risk of chronic diseases. This paper will review recent research on the phytochemicals and antioxidant activity of whole grains and their unique contribution to the health benefits of whole grains.
The evidence of the relationship between fiber intake and control of diabetes is mixed. The purpose of this study was to determine if an increase in dietary fiber affects glycosylated hemoglobin (HbA1c) and fasting blood glucose in patients with type 2 diabetes mellitus.
Randomized studies published from January 1, 1980, to December 31, 2010, that involved an increase in dietary fiber intake as an intervention, evaluated HbA1c and/or fasting blood glucose as an outcome, and used human participants with known type 2 diabetes mellitus were selected for review.
Fifteen studies met inclusion and exclusion criteria. The overall mean difference of fiber versus placebo was a reduction of fasting blood glucose of 0.85 mmol/L (95% CI, 0.46-1.25). Dietary fiber as an intervention also had an effect on HbA1c over placebo, with an overall mean difference of a decrease in HbA1c of 0.26% (95% CI, 0.02-0.51).
Overall, an intervention involving fiber supplementation for type 2 diabetes mellitus can reduce fasting blood glucose and HbA1c. This suggests that increasing dietary fiber in the diet of patients with type 2 diabetes is beneficial and should be encouraged as a disease management strategy.
Hypertension is a major public health problem. While many dietary factors affect the risk of developing hypertension, limited data are available on the association between consumption of breakfast cereal and incident hypertension. We examined the association between breakfast cereal consumption and the risk of hypertension.
We prospectively analyzed data from 13,368 male participants of the Physicians' Health Study I. Consumption of breakfast cereals was estimated using an abbreviated food frequency questionnaire and incident hypertension was ascertained through yearly follow-up questionnaires.
The average age of study participants was 52.4 ± 8.9 years (range 39.7-85.9) during the initial assessment of cereal intake (1981-1983). During a mean follow up of 16.3 years, 7267 cases of hypertension occurred. The crude incidence rates of hypertension were 36.7, 34.0, 31.7, and 29.6 cases/1000 person-years for people reporting breakfast cereal intake of 0, ≤1, 2-6, and ≥7 servings/week, respectively. In a Cox regression model adjusting for age, smoking, body mass index, alcohol consumption, fruit and vegetable consumption, physical activity, and history of diabetes mellitus, hazard ratios (95% CI) for hypertension were 1.0 (reference), 0.93 (0.88-0.99), 0.88 (0.83-0.94), and 0.81 (0.75-0.86) from the lowest to the highest category of cereal consumption, respectively (p for trend <0.0001). This association was strongest for whole grain cereals and was observed in lean as well as overweight or obese participants.
The results of this longitudinal cohort study suggest that whole grain breakfast cereal consumption confers a lower risk of hypertension in middle-aged adult males.
Plant flavonoids show anti-inflammatory activity in vitro and in vivo. Although not fully understood, several action mechanisms are proposed to explain in vivo anti-inflammatory action. One of the important mechanisms is an inhibition of eicosanoid generating enzymes including phospholipase A2, cyclooxygenases, and lipoxygenases, thereby reducing the concentrations of prostanoids and leukotrienes. Recent studies have also shown that certain flavonoids, especially flavone derivatives, express their anti-inflammatory activity at least in part by modulation of proinflammatory gene expression such as cyclooxygenase-2, inducible nitric oxide synthase, and several pivotal cytokines. Due to these unique action mechanisms and significant in vivo activity, flavonoids are considered to be reasonable candidates for new anti-inflammatory drugs. To clearly establish the therapeutic value in inflammatory disorders, in vivo anti-inflammatory activity, and action mechanism of varieties of flavonoids need to be further elucidated. This review summarizes the effect of flavonoids on eicosanoid and nitric oxide generating enzymes and the effect on expression of proinflammatory genes. In vivo anti-inflammatory activity is also discussed. As natural modulators of proinflammatory gene expression, certain flavonoids have a potential for new anti-inflammatory agents.
A meta-analysis was performed on epidemiologic studies to assess the relation between β-glucan consumption from oats and from barley on blood cholesterol level, triglyceride/triacylglycerol (TGL/TAG) level, and blood glucose level (BGL) in humans. In addition, the effect of β-glucan on total cholesterol (TC) and BGL was translated into an empirical dose-response model.
Thirty research articles that evaluated the effect of different exposure levels of β-glucan on blood cholesterol and BGL were analyzed, yielding 126 clinical studies.
There was a significant inverse relation in TC (-0.60 mmol/L, 95% confidence interval [CI] -0.85 to -0.34), low-density lipoprotein (-0.66 mmol/L, 95% CI -0.96 to -0.36), and TGL/TAG (-0.04 mmol/L, 95% CI -0.15 to 0.07) after consumption of β-glucan. In contrast, an increase in high-density lipoprotein cholesterol was noted (0.03 mmol/L, 95% CI -0.06 to 0.13) with the random-effect model. The analysis showed a significant change in BGL (-2.58 mmol/L, 95% CI -3.22 to -1.84) with high heterogeneity between (I(2) = 97%) and across (τ(2) = 5.88) the studies. The fixed-effect model showed a significant change in TC, low-density lipoprotein, and BGL, whereas it showed no significant changes in high-density lipoprotein and TGL/TAG. The dose-response model showed that a 3-g/d dose of oat or barley β-glucan was sufficient to decrease TC.
Consumption of 3 g/d of oat or barley β-glucan is sufficient to decrease blood cholesterol, whereas the effect on BGL is still inconclusive, with high heterogeneity, and requires further clinical research studies with longer intervention periods.
The present review of the literature on lignan physiology and lignan intervention and epidemiological studies was conducted to determine if lignans decrease the risks of cardiovascular disease in Western populations. Five intervention studies using flaxseed lignan supplements indicated beneficial associations with C-reactive protein, and a meta-analysis that included these studies also suggested lignans have a lowering effect on plasma total and low-density lipoprotein cholesterol. Three intervention studies using sesamin supplements indicated possible lipid- and blood pressure-lowering associations. Eleven human observational epidemiological studies examined dietary intakes of lignans in relation to cardiovascular disease risk. Five showed decreased risk with either increasing dietary intakes of lignans or increased levels of serum enterolactone (an enterolignan used as a biomarker of lignan intake), five studies were of borderline significance, and one was null. The associations between lignans and decreased risk of cardiovascular disease are promising, but they are yet not well established, perhaps due to low lignan intakes in habitual Western diets. At the higher doses used in intervention studies, associations were more evident.
A whole grain consists of the intact, ground, cracked, or flaked caryopsis, whose principal anatomical components--the starchy endosperm, germ, and bran--are present in the same relative proportions as they exist in the intact caryopsis. Whole grain food products can be intact, consisting of the original composition of bran, germ, and endosperm, throughout the entire lifetime of the product, or reconstituted, in which one or more of the original components of a whole grain is recombined to the relative proportion naturally occurring in the grain kernel. Increased consumption of whole grains has been associated with reduced risk of major chronic diseases including cardiovascular disease, type II diabetes, and some cancers. Whole grain foods offer a wide range of phytochemicals with health benefits that are only recently becoming recognized. The unique phytochemicals in whole grains are proposed to be responsible for the health benefits of whole grain consumption. In this paper, whole grain phytochemicals and the health benefits associated with their consumption are reviewed.
Preventieve maatregelen zijn nodig om de snelle toename van type 2 diabetes mellitus (T2DM) patiënten te stoppen. Veranderingen in het voedselpatroon, bv reductie van verzadigde vetten, kunnen daaraan een aanzienlijke bijdrage leveren. De rol van zetmeelrijke producten, zoals aardappelen en graanproducten, is echter nog niet systematisch onderzocht. Granen worden vóór de verwerking meestal geraffineerd, hetgeen betekent dat de kiem en het zemelgedeelte worden verwijderd; volkorengraanproducten daarentegen bevatten nog al deze bestanddelen. In ons onderzoek hebben wij gevonden dat het risico op het ontstaan van T2DM lager is bij een hoge inname van volkorengraanproducten. Dit zou kunnen worden toegeschreven aan langzaam verteerbare koolhydraten in volkorengraanproducten of aan het hoge gehalte aan niet-verteerbare koolhydraten (zemelen). We hebben verder onderzocht welke van deze eigenschappen risicofactoren voor T2DM kunnen beïnvloeden. Belangrijke factoren bij het ontstaan van T2DM zijn weefselongevoeligheid voor insuline en een lage chronische ontsteking. Het effect van langzaam verteerbare koolhydraten op deze risicofactoren is nog niet duidelijk. Echter, de niet-verteerbare koolhydraten blijken de potentie te hebben de weefselgevoeligheid voor insuline te verhogen. Ons experimenteel onderzoek heeft aangetoond dat dit effect veroorzaakt kan worden door korte-keten vetzuren, die in het dikke darm ontstaan door omzetting van niet-verteerbare koolhydraten. Verder hebben we vastgesteld dat volkorengraanproducten, die ’s avonds worden gegeten de volgende ochtend de ontstekingsreactie na een glucosebelasting verminderen. Dit effect zou door korte-keten vetzuren of fytochemicaliën in graanvezels kunnen worden veroorzaakt. Deze interessante nieuwe bevinding kan een aanknopingspunt zijn voor nader onderzoek naar de ontstekingsremmende capaciteit van volkorengraanproducten. Zie: Samenvatting.
Weight loss and consumption of viscous fibers both lower low-density lipoprotein (LDL) cholesterol levels. We evaluated whether or not a whole-grain, ready-to-eat (RTE) oat cereal containing viscous fiber, as part of a dietary program for weight loss, lowers LDL cholesterol levels and improves other cardiovascular disease risk markers more than a dietary program alone.
Randomized, parallel-arm, controlled trial.
Free-living, overweight and obese adults (N=204, body mass index 25 to 45) with baseline LDL cholesterol levels 130 to 200 mg/dL (3.4 to 5.2 mmol/L) were randomized; 144 were included in the main analysis of participants who completed the trial without significant protocol violations.
Two portions per day of whole-grain RTE oat cereal (3 g/day oat b-glucan) or energy-matched low-fiber foods (control), as part of a reduced energy ( approximately 500 kcal/day deficit) dietary program that encouraged limiting consumption of foods high in energy and fat, portion control, and regular physical activity.
Fasting lipoprotein levels, waist circumference, triceps skinfold thickness, and body weight were measured at baseline and weeks 4, 8, 10, and 12.
LDL cholesterol level was reduced significantly more with whole-grain RTE oat cereal vs control (-8.7+/-1.0 vs -4.3+/-1.1%, P=0.005). Total cholesterol (-5.4+/-0.8 vs -2.9+/-0.9%, P=0.038) and non-high-density lipoprotein-cholesterol (-6.3+/-1.0 vs -3.3+/-1.1%, P=0.046) were also lowered significantly more with whole-grain RTE oat cereal, whereas high-density lipoprotein and triglyceride responses did not differ between groups. Weight loss was not different between groups (-2.2+/-0.3 vs -1.7+/-0.3 kg, P=0.325), but waist circumference decreased more (-3.3+/-0.4 vs -1.9+/-0.4 cm, P=0.012) with whole-grain RTE oat cereal. Larger reductions in LDL, total, and non-high-density lipoprotein cholesterol levels and waist circumference were evident as early as week 4 in the whole-grain RTE oat cereal group.
Consumption of a whole-grain RTE oat cereal as part of a dietary program for weight loss had favorable effects on fasting lipid levels and waist circumference.
Oats are known to be a healthy food for the heart due mainly to their high beta-glucan content. In addition, they contain more than 20 unique polyphenols, avenanthramides, which have shown strong antioxidant activity in vitro and in vivo. The polyphenols of oats have also recently been shown to exhibit anti-inflammatory, antiproliferative, and anti-itching activity, which may provide additional protection against coronary heart disease, colon cancer, and skin irritation.
Although dietary fiber has been hypothesized to lower risk of breast cancer by modulating estrogen metabolism, the association between dietary fiber intake and risk of breast cancer by hormone receptor status is unclear.
The objective was to examine the relation of dietary fiber intake to breast cancer by hormone receptor status and histologic type among postmenopausal women in the National Institutes of Health-AARP Diet and Health Study (n = 185,598; mean age: 62 y).
Dietary intakes were assessed with a food-frequency questionnaire. Incident breast cancer cases were identified through linkage with state cancer registries. Cox proportional hazard models were used to estimate relative risks (RRs) and 2-sided 95% CIs.
During an average of 7 y of follow-up, 5461 breast cancer cases were identified, of which 3341 cases had estrogen receptor (ER) and progesterone receptor (PR) status. Dietary fiber intake was inversely associated with breast cancer risk [RR for the highest quintile (Q5) compared with the lowest quintile (Q1): 0.87; 95% CI: 0.77, 0.98; P for trend: 0.02]. The inverse association appeared to be stronger for ER(-)/PR(-) tumors (RR(Q5vsQ1): 0.56; 95% CI: 0.35, 0.90; P for trend: 0.008; 366 cases) than for ER(+)/PR(+) tumors (RR(Q5vsQ1): 0.95; 95% CI: 0.76, 1.20; P for trend: 0.47; 1641 cases). The RR(Q5vsQ1) of lobular tumors was 0.66 (95% CI: 0.44, 0.97; P for trend: 0.04), and the RR(Q5vsQ1) of ductal tumors was 0.90 (95% CI: 0.77, 1.04; P for trend: 0.10). Fiber from grains, fruit, vegetables, and beans was not related to breast cancer.
Our findings suggest that dietary fiber can play a role in preventing breast cancer through nonestrogen pathways among postmenopausal women.
To characterize the range of variation in lignan content and composition caused by genotype and environment, seven dietary lignans, i.e., 7-hydroxymatairesinol, secoisolariciresinol, matairesinol, lariciresinol, pinoresinol, medioresinol, and syringaresinol, were analyzed by high-performance liquid chromatography-tandem mass spectrometry in whole-grain extracts of cereal samples collected at eight locations in Finland. In all, 28 winter rye, 73 spring wheat, and 55 spring oat samples were analyzed, representing 6, 9, and 5 cultivars, respectively. The total lignan content showed huge variations within the same cereal species: the range was 2500-6700 microg/100 g in the rye samples, 340-2270 microg/100 g in the wheat samples, and 820-2550 microg/100 g in the oat samples. The variations seemed to depend largely upon genetic differences. In rye, also environmental conditions affected the lignan content through grain size; smaller grains had significantly lower total lignan, syringaresinol, and lariciresinol content than larger grains. This study shows that varying cereal lignan concentrations reported in different studies may be, besides differences in analytical methods, largely dependent upon natural variations.
It has been suggested that lignan intake may decrease the risk for cardiovascular disease (CVD) by modifying traditional risk factors as well as aortic stiffness. However, the role of dietary lignans on the vascular system is largely unknown. The objective was to investigate whether dietary intake of plant lignans in a free-living population was associated with markers of vascular inflammation and function.
We performed a cross-sectional study in 242 (151 males) men and post-menopausal women. Anthropometric characteristics and lignan intake were evaluated. Soluble intercellular adhesion molecule-1 (sICAM-1), insulin, high-sensitive C-reactive protein, glucose, total cholesterol, HDL-cholesterol and triacylglycerols were measured in fasting blood samples. Brachial flow-mediated dilation (FMD) measurements were available for 101 subjects (56 males). Median (interquartile range) daily intake of matairesinol (MAT), secoisolariciresinol (SECO), pinoresinol (PINO), lariciresinol (LARI), and total lignans was 20.9 microg (17.4), 335.3 microg (289.1), 96.7 microg (91.1), 175.7 microg (135.8), and 665.5 microg (413.7), respectively, as assessed by 3-day weighed food record. Plasma concentrations of sICAM-1 (whole sample) significantly decreased (mean (95%CI) = 358 microg/L (320-401), 276 microg/L (252-303), 298 microg/L (271-326), and 269 microg/L (239-303), P per trend 0.013) and FMD values (FMD sub-group) significantly increased (4.1% (2.2-6.0), 5.7% (4.3-7.2), 6.4% (4.9-7.8), and 8.1% (6.3-10.0), P per trend 0.016) across quartiles of energy-adjusted MAT intake, even after adjustment for relevant clinical and dietary variables. Intake of SECO was also inversely related to plasma sICAM-1 (P per trend 0.018), but not to FMD values. No relationship between intake of PINO, LARI or total lignans and either sICAM-1 or FMD values was observed.
Higher MAT intakes in the context of a typical Northern Italian diet are associated to lower vascular inflammation and endothelial dysfunction, which could have some implications in CVD prevention.