[Show abstract][Hide abstract] ABSTRACT: Background:
Debate over the role of fructose in mediating cardiovascular risk remains active. To update the evidence on the effect of fructose on established therapeutic lipid targets for cardiovascular disease (low-density lipoprotein cholesterol [LDL]-C, apolipoprotein B, non-high-density lipoprotein cholesterol [HDL-C]), and metabolic syndrome (triglycerides and HDL-C), we conducted a systematic review and meta-analysis of controlled feeding trials.
Methods and results:
MEDLINE, EMBASE, CINHAL, and the Cochrane Library were searched through July 7, 2015 for controlled feeding trials with follow-up ≥7 days, which investigated the effect of oral fructose compared to a control carbohydrate on lipids (LDL-C, apolipoprotein B, non-HDL-C, triglycerides, and HDL-C) in participants of all health backgrounds. Two independent reviewers extracted relevant data. Data were pooled using random effects models and expressed as mean difference with 95% CI. Interstudy heterogeneity was assessed (Cochran Q statistic) and quantified (I(2) statistic). Eligibility criteria were met by 51 isocaloric trials (n=943), in which fructose was provided in isocaloric exchange for other carbohydrates, and 8 hypercaloric trials (n=125), in which fructose supplemented control diets with excess calories compared to the control diets alone without the excess calories. Fructose had no effect on LDL-C, non-HDL-C, apolipoprotein B, triglycerides, or HDL-C in isocaloric trials. However, in hypercaloric trials, fructose increased apolipoprotein B (n=2 trials; mean difference = 0.18 mmol/L; 95% CI: 0.05, 0.30; P=0.005) and triglycerides (n=8 trials; mean difference = 0.26 mmol/L; 95% CI: 0.11, 0.41; P<0.001). The study is limited by small sample sizes, limited follow-up, and low quality scores of the included trials.
Pooled analyses showed that fructose only had an adverse effect on established lipid targets when added to existing diets so as to provide excess calories (+21% to 35% energy). When isocalorically exchanged for other carbohydrates, fructose had no adverse effects on blood lipids. More trials that are larger, longer, and higher quality are required.
Clinical trials registration:
URL: https://www.clinicaltrials.gov/. Unique Identifier: NCT01363791.
Journal of the American Heart Association 09/2015; 4(9). DOI:10.1161/JAHA.114.001700 · 4.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The cell walls (dietary fibre) of edible plants, which consist of mainly non-starch polysaccharides, play an important role in regulating nutrient bioaccessibility (release) during digestion in the upper gastrointestinal tract. Recent studies have shown that structurally-intact cell walls hinder lipid release from the parenchyma cells of almond seeds. A theoretical model was developed to predict the bioaccessibility of lipid using simple geometry and data on cell dimensions and particle size for calculating the number of ruptured cells in cut almond cubes. Cubes (2 mm) and finely-ground flour of low and high lipid bioaccessibility, respectively, were prepared from almond cotyledon. The model predictions were compared with data from in vitro gastric and duodenal digestion of almond cubes and flour. The model showed that lipid bioaccessibility is highly dependent on particle size and cell diameter. Only a modified version of the model (the Extended Theoretical Model, ETM), in which the cells at the edges and corners were counted once only, was acceptable for the full range of particle sizes. Lipid release values predicted from the ETM were 5.7% for almond cubes and 42% for almond flour. In vitro digestion of cubes and flour showed that lipid released from ruptured cells was available for hydrolysis and resulted in lipid losses of 9.9 and 39.3%, respectively. The ETM shows considerable potential for predicting lipid release in the upper gastrointestinal tract. Further work is warranted to evaluate the efficacy of this model to accurately predict nutrient bioaccessibility in a broad range of edible plants.
Food & Function 10/2014; 5(12). DOI:10.1039/C4FO00659C · 2.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives: Although most controlled feeding trials have failed to show an adverse effect of fructose on blood pressure, concerns continue to be raised regarding the role of fructose in hypertension. To quantify the association between fructose-containing sugar (high-fructose corn syrup, sucrose, and fructose) intake and incident hypertension, a systematic review and meta-analysis of prospective cohort studies was undertaken.
Methods: MEDLINE, EMBASE, CINAHL and the Cochrane Library (through February 5, 2014) were searched for relevant studies. Two independent reviewers reviewed and extracted relevant data. Risk estimates were aggregated comparing the lowest (reference) quintile with highest quintile of intake using inverse variance random effect models and expressed as risk ratios (RR) with 95% confidence intervals (CIs). Interstudy heterogeneity was assessed (Cochran Q statistic) and quantified (I
2 statistic). The Newcastle–Ottawa Scale assessed study quality. Clinicaltrials.gov NCT01608620.
Results: Eligibility criteria were met by 3 prospective cohorts (n = 37,375 men and 185,855 women) with 58,162 cases of hypertension observed over 2,502,357 person-years of follow-up. Median fructose intake was 5.7–6.0% total energy in the lowest quintile and 13.9–14.3% total energy in the highest quintile. Fructose intake was not associated with incident hypertension (RR = 1.02, 95% CI, 0.99–1.04), with no evidence of heterogeneity (I
2 = 0%, p = 0.59). Spline curve modeling showed a U-shaped relationship with a negative association at intakes ≤50th percentile (∼10% total energy) and a positive association at higher intakes.
Conclusions: Total fructose intake was not associated with an increased risk of hypertension in 3 large prospective cohorts of U.S. men and women.
Journal of the American College of Nutrition 08/2014; 33(4):1-12. DOI:10.1080/07315724.2014.916237 · 1.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Consumption of almonds has been shown to be associated with a decreased risk of CHD, which may be related to their fatty acid (FA) composition. However, the effect of almond consumption on the serum FA composition is not known. Therefore, in the present study, we investigated whether almond consumption would alter the serum FA profile and risk of CHD, as calculated using Framingham's 10-year risk score, in a dose-dependent manner in hyperlipidaemic individuals when compared with a higher-carbohydrate control group using dietary interventions incorporating almonds. A total of twenty-seven hyperlipidaemic individuals consumed three isoenergetic (mean 1770 kJ/d) supplements during three 1-month dietary phases: (1) full-dose almonds (50-100 g/d); (2) half-dose almonds with half-dose muffins; (3) full-dose muffins. Fasting blood samples were obtained at weeks 0 and 4 for the determination of FA concentrations. Almond intake (g/d) was found to be inversely associated with the estimated Framingham 10-year CHD risk score (P= 0·026). In both the half-dose and full-dose almond groups, the proportions of oleic acid (OA) and MUFA in the TAG fraction (half-almond: OA P= 0·003; MUFA P= 0·004; full-almond: OA P< 0·001; MUFA P< 0·001) and in the NEFA fraction (half-almond: OA P= 0·01; MUFA P= 0·04; full-almond: OA P= 0·12; MUFA P= 0·06) increased. The estimated Framingham 10-year CHD risk score was inversely associated with the percentage change of OA (P= 0·011) and MUFA (P= 0·016) content in the TAG fraction. The proportions of MUFA in the TAG and NEFA fractions were positively associated with changes in HDL-cholesterol concentrations. Similarly, the estimated Framingham 10-year CHD risk score was inversely associated with the percentage change of OA (P= 0·069) and MUFA content in the NEFA fraction (P= 0·009). In conclusion, the results of the present study indicate that almond consumption increases OA and MUFA content in serum TAG and NEFA fractions, which are inversely associated with CHD lipid risk factors and overall estimated 10-year CHD risk.
British Journal Of Nutrition 08/2014; 112(7):1-10. DOI:10.1017/S0007114514001640 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective
To assess the effect of dietary pulses (beans, peas, chickpeas, lentils) on acute satiety and second meal intake, a systematic review and meta-analysis was conducted.MethodsMEDLINE, EMBASE, CINAHL, and the Cochrane Registry (through May 6, 2013) were searched for acute controlled trials examining the effect of dietary pulses on postprandial satiety or second meal intake compared with isocaloric controls. Two independent reviewers extracted data and assessed methodological quality and risk of bias. Data were pooled by generic inverse variance random effects models and expressed as ratio of means (RoMs) for satiety and mean differences (MDs) for second meal food intake, with 95% confidence intervals (95% CIs). Heterogeneity was assessed (Q statistic) and quantified (I2 statistic). Protocol registration: clinicaltrials.gov identifier, NCT01605422.ResultsNine trials met the eligibility criteria. Dietary pulses produced a 31% greater satiety incremental area under the curve (IAUC) (RoM = 1.31, 95% CI: 1.09 to 1.58, P = 0.004; Phet = 0.96; I2 = 0%) without affecting second meal intake (MD = −19.94, 95% CI: −75-35, P = 0.48; Phet = 0.01; I2 = 63%). Our data are limited by the small sample sizes, narrow participant characteristics and significant unexplained heterogeneity among the available trials.Conclusions
Pooled analyses show that dietary pulses contribute to acute satiety but not second meal intake.
[Show abstract][Hide abstract] ABSTRACT: Background and Aims
Nut consumption has been associated with decreased risk of coronary heart disease (CHD) and type 2 diabetes which has been largely attributed to their healthy fatty acid profile, yet this has not been ascertained. Therefore, we investigated the effect of nut consumption on serum fatty acid concentrations and how these relate to changes in markers of glycemic control and calculated CHD risk score in type 2 diabetes.
Methods and Results
117 subjects with type 2 diabetes consumed one of three iso-energetic (mean 475 kcal/d) supplements for 12 weeks: 1. full-dose nuts (50-100g/d); 2. half-dose nuts with half-dose muffins; and 3. full-dose muffins. In this secondary analysis, fatty acid concentrations in the phospholipid, triacylglycerol, free fatty acid, and cholesteryl ester fractions from fasting blood samples obtained at baseline and week 12 were analyzed using thin layer and gas chromatography. Full-dose nut supplementation significantly increased serum oleic acid (OA) and MUFAs compared to the control in the phospholipid fraction (OA: P=0.036; MUFAs: P=0.024). Inverse associations were found with changes in CHD risk versus changes in OA and MUFAs in the triacylglycerol (r=-0.256, P=0.011; r=-0.228, P=0.024, respectively) and phospholipid (r=-0.278, P=0.006; r=-0.260, P=0.010, respectively) fractions. In the cholesteryl ester fraction, change in MUFAs was inversely associated with markers of glycemic control (HbA1c: r=-0.250, P=0.013; fasting blood glucose: r=-0.395, P<0.0001).
Nut consumption increased OA and MUFA content of the serum phospholipid fraction, which was inversely associated with CHD risk factors and 10-year CHD risk.
Clinical Trial Reg. No.
[Show abstract][Hide abstract] ABSTRACT: Background: Tree nut consumption has been associated with reduced diabetes risk, however, results from randomized trials on glycemic control have been inconsistent. Objective: To provide better evidence for diabetes guidelines development, we conducted a systematic review and meta-analysis of randomized controlled trials to assess the effects of tree nuts on markers of glycemic control in individuals with diabetes. Data Sources: MEDLINE, EMBASE, CINAHL, and Cochrane databases through 6 April 2014. Study Selection: Randomized controlled trials >= 3 weeks conducted in individuals with diabetes that compare the effect of diets emphasizing tree nuts to isocaloric diets without tree nuts on HbA1c, fasting glucose, fasting insulin, and HOMA-IR. Data Extraction and Synthesis: Two independent reviewer's extracted relevant data and assessed study quality and risk of bias. Data were pooled by the generic inverse variance method and expressed as mean differences (MD) with 95% CI's. Heterogeneity was assessed (Cochran Q-statistic) and quantified (I-2). Results: Twelve trials (n = 450) were included. Diets emphasizing tree nuts at a median dose of 56 g/d significantly lowered HbA1c (MD = -0.07% [95% CI: -0.10, -0.03%]; P = 0.0003) and fasting glucose (MD = -0.15 mmol/L [95% CI: -0.27, -0.02 mmol/L]; P = 0.03) compared with control diets. No significant treatment effects were observed for fasting insulin and HOMA-IR, however the direction of effect favoured tree nuts. Limitations: Majority of trials were of short duration and poor quality. Conclusions: Pooled analyses show that tree nuts improve glycemic control in individuals with type 2 diabetes, supporting their inclusion in a healthy diet. Owing to the uncertainties in our analyses there is a need for longer, higher quality trials with a focus on using nuts to displace high-glycemic index carbohydrates.
PLoS ONE 07/2014; 9(7):e103376. DOI:10.1371/journal.pone.0103376 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective To provide a broader evidence summary to inform dietary guidelines of the effect of tree nuts on criteria of the metabolic syndrome (MetS).
Design We conducted a systematic review and meta-analysis of the effect of tree nuts on criteria of the MetS.
Data sources We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library (through 4 April 2014).
Eligibility criteria for selecting studies We included relevant randomised controlled trials (RCTs) of ≥3 weeks reporting at least one criterion of the MetS.
Data extraction Two or more independent reviewers extracted all relevant data. Data were pooled using the generic inverse variance method using random effects models and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed by the Cochran Q statistic and quantified by the I2 statistic. Study quality and risk of bias were assessed.
Results Eligibility criteria were met by 49 RCTs including 2226 participants who were otherwise healthy or had dyslipidaemia, MetS or type 2 diabetes mellitus. Tree nut interventions lowered triglycerides (MD=−0.06 mmol/L (95% CI −0.09 to −0.03 mmol/L)) and fasting blood glucose (MD=−0.08 mmol/L (95% CI −0.16 to −0.01 mmol/L)) compared with control diet interventions. There was no effect on waist circumference, high-density lipoprotein cholesterol or blood pressure with the direction of effect favouring tree nuts for waist circumference. There was evidence of significant unexplained heterogeneity in all analyses (p<0.05).
Conclusions Pooled analyses show a MetS benefit of tree nuts through modest decreases in triglycerides and fasting blood glucose with no adverse effects on other criteria across nut types. As our conclusions are limited by the short duration and poor quality of the majority of trials, as well as significant unexplained between-study heterogeneity, there remains a need for larger, longer, high-quality trials.
Trial registration number NCT01630980.
BMJ Open 07/2014; 4(7):e004660. DOI:10.1136/bmjopen-2013-004660 · 2.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
Despite their independent cardiovascular disease (CVD) advantages, effects of α-linolenic acid (ALA), monounsaturated fatty acid (MUFA), and low-glycemic-load (GL) diets have not been assessed in combination. We therefore determined the combined effect of ALA, MUFA, and low GL on glycemic control and CVD risk factors in type 2 diabetes.
Research design and methods:
The study was a parallel design, randomized trial wherein each 3-month treatment was conducted in a Canadian academic center between March 2011 and September 2012 and involved 141 participants with type 2 diabetes (HbA1c 6.5%-8.5% [48-69 mmol/mol]) treated with oral antihyperglycemic agents. Participants were provided with dietary advice on either a low-GL diet with ALA and MUFA given as a canola oil-enriched bread supplement (31 g canola oil per 2,000 kcal) (test) or a whole-grain diet with a whole-wheat bread supplement (control). The primary outcome was HbA1c change. Secondary outcomes included calculated Framingham CVD risk score and reactive hyperemia index (RHI) ratio.
Seventy-nine percent of the test group and 90% of the control group completed the trial. The test diet reduction in HbA1c units of -0.47% (-5.15 mmol/mol) (95% CI -0.54% to -0.40% [-5.92 to -4.38 mmol/mol]) was greater than that for the control diet (-0.31% [-3.44 mmol/mol] [95% CI -0.38% to -0.25% (-4.17 to -2.71 mmol/mol)], P = 0.002), with the greatest benefit observed in those with higher systolic blood pressure (SBP). Greater reductions were seen in CVD risk score for the test diet, whereas the RHI ratio increased for the control diet.
A canola oil-enriched low-GL diet improved glycemic control in type 2 diabetes, particularly in participants with raised SBP, whereas whole grains improved vascular reactivity.
Diabetes Care 06/2014; 37(7). DOI:10.2337/dc13-2990 · 8.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND:Evidence from controlled trials encourages the intake of dietary pulses (beans, chickpeas, lentils and peas) as a method of improving dyslipidemia, but heart health guidelines have stopped short of ascribing specific benefits to this type of intervention or have graded the beneficial evidence as low. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction. METHODS:We searched electronic databases and bibliographies of selected trials for relevant articles published through Feb. 5, 2014. We included RCTs of at least 3 weeks' duration that compared a diet emphasizing dietary pulse intake with an isocaloric diet that did not include dietary pulses. The lipid targets investigated were low-density lipoprotein (LDL) cholesterol, apolipoprotein B and non-high-density lipoprotein (non-HDL) cholesterol. We pooled data using a randomeffects model. RESULTS:We identified 26 RCTs (n = 1037) that satisfied the inclusion criteria. Diets emphasizing dietary pulse intake at a median dose of 130 g/d (about 1 serving daily) significantly lowered LDL cholesterol levels compared with the control diets (mean difference -0.17 mmol/L, 95% confidence interval -0.25 to -0.09 mmol/L). Treatment effects on apolipoprotein B and non-HDL cholesterol were not observed. INTERPRETATION:Our findings suggest that dietary pulse intake significantly reduces LDL cholesterol levels. Trials of longer duration and higher quality are needed to verify these results. Trial registration: ClinicalTrials.gov, no. NCT01594567.
Canadian Medical Association Journal 04/2014; 186(8). DOI:10.1503/cmaj.131727 · 5.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background/Objectives:
In the absence of consistent clinical evidence, there are concerns that fructose contributes to non-alcoholic fatty liver disease (NAFLD). To determine the effect of fructose on markers of NAFLD, we conducted a systematic review and meta-analysis of controlled feeding trials.
We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library (through 3 September 2013). We included relevant trials that involved a follow-up of ⩾7 days. Two reviewers independently extracted relevant data. Data were pooled by the generic inverse variance method using random effects models and expressed as standardized mean difference (SMD) for intrahepatocellular lipids (IHCL) and mean difference (MD) for alanine aminotransferase (ALT). Inter-study heterogeneity was assessed (Cochran Q statistic) and quantified (I2 statistic).
Eligibility criteria were met by eight reports containing 13 trials in 260 healthy participants: seven isocaloric trials, in which fructose was exchanged isocalorically for other carbohydrates, and six hypercaloric trials, in which the diet was supplemented with excess energy (+21–35% energy) from high-dose fructose (+104–220 g/day). Although there was no effect of fructose in isocaloric trials, fructose in hypercaloric trials increased both IHCL (SMD=0.45 (95% confidence interval (CI): 0.18, 0.72)) and ALT (MD=4.94 U/l (95% CI: 0.03, 9.85)).
Few trials were available for inclusion, most of which were small, short (⩽4 weeks), and of poor quality.
Isocaloric exchange of fructose for other carbohydrates does not induce NAFLD changes in healthy participants. Fructose providing excess energy at extreme doses, however, does raise IHCL and ALT, an effect that may be more attributable to excess energy than fructose. Larger, longer and higher-quality trials of the effect of fructose on histopathological NAFLD changes are required.
Canadian Journal of Diabetes 02/2014; 36(5):S10. DOI:10.1016/j.jcjd.2012.07.048 · 2.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
In the absence of consistent clinical evidence, concerns have been raised that fructose raises postprandial triglycerides.
A systematic review and meta-analysis was conducted to assess the effect of fructose on postprandial triglycerides.
Relevant studies were identified from MEDLINE, EMBASE, and Cochrane databases (through September 3, 2013).
Relevant clinical trials of ≥7-days were included in the analysis.
Two independent reviewers extracted relevant data with disagreements reconciled by consensus. The Heyland Methodological Quality Score (MQS) assessed study quality. Data were pooled by the generic inverse variance method using random effects models and expressed as standardized mean differences (SMD) with 95% confidence intervals (CI). Heterogeneity was assessed (Cochran Q statistic) and quantified (I2 statistic).
Eligibility criteria were met by 14 isocaloric trials (n = 290), in which fructose was exchanged isocalorically for other carbohydrate in the diet, and two hypercaloric trials (n = 33), in which fructose supplemented the background diet with excess energy from high-dose fructose compared with the background diet alone (without the excess energy). There was no significant effect in the isocaloric trials (SMD: 0.14 [95% CI: −0.02, 0.30]) with evidence of considerable heterogeneity explained by a single trial. Hypercaloric trials, however, showed a significant postprandial triglyceride raising-effect of fructose (SMD: 0.65 [95% CI: 0.30, 1.01]).
Most of the available trials were small, short, and of poor quality. Interpretation of the isocaloric trials is complicated by the large influence of a single trial.
Pooled analyses show that fructose in isocaloric exchange for other carbohydrate does not increase postprandial triglycerides, although an effect cannot be excluded under all conditions. Fructose providing excess energy does increase postprandial triglycerides. Larger, longer, and higher-quality trials are needed.
ClinicalTrials.gov identifier, NCT01363791.
Canadian Journal of Diabetes 01/2014; 36(5):S19. DOI:10.1016/j.jcjd.2012.07.079 · 2.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Low-carbohydrate diets may be useful for weight loss. Diets high in vegetable proteins and oils may reduce the risk of coronary heart disease. The main objective was to determine the longer term effect of a diet that was both low-carbohydrate and plant-based on weight loss and low-density lipoprotein cholesterol (LDL-C).
A parallel design study of 39 overweight hyperlipidaemic men and postmenopausal women conducted at a Canadian university-affiliated hospital nutrition research centre from April 2005 to November 2006.
Participants were advised to consume either a low-carbohydrate vegan diet or a high-carbohydrate lacto-ovo vegetarian diet for 6 months after completing 1-month metabolic (all foods provided) versions of these diets. The prescribed macronutrient intakes for the low-carbohydrate and high-carbohydrate diets were: 26% and 58% of energy from carbohydrate, 31% and 16% from protein and 43% and 25% from fat, respectively.
Change in body weight.
23 participants (50% test, 68% control) completed the 6-month ad libitum study. The approximate 4 kg weight loss on the metabolic study was increased to -6.9 kg on low-carbohydrate and -5.8 kg on high-carbohydrate 6-month ad libitum treatments (treatment difference (95% CI) -1.1 kg (-2.1 to 0.0), p=0.047). The relative LDL-C and triglyceride reductions were also greater on the low-carbohydrate treatment (treatment difference (95% CI) -0.49 mmol/L (-0.70 to -0.28), p<0.001 and -0.34 mmol/L (-0.57 to -0.11), p=0.005, respectively), as were the total cholesterol:HDL-C and apolipoprotein B:A1 ratios (-0.57 (-0.83, -0.32), p<0.001 and -0.05 (-0.09, -0.02), p=0.003, respectively).
A self-selected low-carbohydrate vegan diet, containing increased protein and fat from gluten and soy products, nuts and vegetable oils, had lipid lowering advantages over a high-carbohydrate, low-fat weight loss diet, thus improving heart disease risk factors.
clinicaltrials.gov (http://www.clinicaltrials.gov/), #NCT00256516.
BMJ Open 01/2014; 4(2):e003505. DOI:10.1136/bmjopen-2013-003505 · 2.27 Impact Factor