Effects of wheat and oat-based whole grain foods on serum lipoprotein size and distribution in overweight middle aged people: a randomised controlled trial.

INTRODUCTION: Epidemiological studies suggest three daily servings of whole-grain foods (WGF) might lower cardiovascular disease risk, at least partly by lowering serum lipid levels. We have assessed the effects of consuming three daily portions of wholegrain food (provided as wheat or a mixture of wheat and oats) on lipoprotein subclass size and concentration in a dietary randomised controlled trial involving middle aged healthy individuals. METHODS: After a 4-week run-in period on a refined diet, volunteers were randomly allocated to a control (refined diet), wheat, or wheat + oats group for 12 weeks. Our servings were determined in order to significantly increase the intakes of non starch polysaccharides to the UK Dietary Reference Value of 18 g per day in the whole grain groups (18.5 g and 16.8 g per day in the wheat and wheat + oats groups respectively in comparison with 11.3 g per day in the control group). Outcome measures were serum lipoprotein subclasses' size and concentration. Habitual dietary intake was assessed prior and during the intervention. Of the 233 volunteers recruited, 24 withdrew and 3 were excluded. RESULTS: At baseline, significant associations were found between lipoprotein size and subclasses' concentrations and some markers of cardiovascular risk such as insulin resistance, blood pressure and serum Inter cellular adhesion molecule 1 concentration. Furthermore, alcohol and vitamin C intake were positively associated with an anti-atherogenic lipoprotein profile, with regards to lipoprotein size and subclasses' distribution. However, none of the interventions with whole grain affected lipoprotein size and profile. CONCLUSION: Our results indicate that three portions of wholegrain foods, irrelevant of the type (wheat or oat-based) do not reduce cardiovascular risk by beneficially altering the size and distribution of lipoprotein subclasses. TRIAL REGISTRATION: www.Controlled-Trials.com ISRCTN 27657880.

A dose-finding trial of the effect of long-term folic acid intervention: implications for food fortification policy.

BACKGROUND: The lowest dose of folic acid required to achieve effective reductions in homocysteine is controversial but important for food fortification policy given recent concerns about the potential adverse effects of overexposure to this vitamin. OBJECTIVE: We compared the effectiveness of 0.2 mg folic acid/d with that of 0.4 and 0.8 mg/d at lowering homocysteine concentrations over a 6-mo period. DESIGN: A randomized dose-finding trial with folic acid was conducted. Of 203 participants screened, 101 patients with ischemic heart disease and 71 healthy volunteers completed the study. Participants were randomly assigned to receive placebo or folic acid at doses of 0.2, 0.4, or 0.8 mg/d for 26 wk; subsamples of patients with ischemic heart disease were also examined at 6 or 12 wk. RESULTS: Participants with higher baseline homocysteine concentrations had the greatest reductions in homocysteine in response to folic acid doses of 0.2 mg (-20.6%), 0.4 mg (-20.7%), and 0.8 mg (-27.8%); in those with lower baseline homocysteine concentrations, the responses were -8.2%, -8.9%, and -8.3%, respectively. No significant differences in homocysteine responses to the different doses were observed. In the patient group sampled at intervals during the intervention, the maximal homocysteine response appeared to be achieved by 6 wk in the 0.8-mg/d group and by 12 wk in the 0.4-mg/d group. However, the homocysteine response was suboptimal in the 0.2-mg/d group at both 6 and 12 wk compared with that at 26 wk. CONCLUSIONS: A folic acid dose as low as 0.2 mg/d can, if administered for 6 mo, effectively lower homocysteine concentrations. Higher doses may not be necessary because they result in no further significant lowering, whereas doses even lower than 0.2 mg/d may be effective in the longer term. Previous trials probably overestimated the folic acid dose required because of a treatment duration that was too short. This trial was registered at clinicaltrials.gov as ISRCTN45296887.

Effect of increased consumption of whole-grain foods on blood pressure and other cardiovascular risk markers in healthy middle-aged persons: a randomized controlled trial.

BACKGROUND: Three daily portions of whole-grain foods could lower cardiovascular disease risk, but a comprehensive intervention trial was needed to confirm this recommendation. OBJECTIVES: We aimed to assess the effects of consumption of 3 daily portions of whole-grain foods (provided as only wheat or a mixture of wheat and oats) on markers of cardiovascular disease risk in relatively high-risk individuals. DESIGN: This was a randomized controlled dietary trial in middle-aged healthy individuals. After a 4-wk run-in period with a refined diet, we randomly allocated volunteers to a control (refined diet), wheat, or wheat + oats group for 12 wk. The primary outcome was a reduction of cardiovascular disease risk factors by dietary intervention with whole grains, which included lipid and inflammatory marker concentrations, insulin sensitivity, and blood pressure. RESULTS: We recruited a total of 233 volunteers; 24 volunteers withdrew, and 3 volunteers were excluded. Systolic blood pressure and pulse pressure were significantly reduced by 6 and 3 mm Hg, respectively, in the whole-grain foods groups compared with the control group. Systemic markers of cardiovascular disease risk remained unchanged apart from cholesterol concentrations, which decreased slightly but significantly in the refined group. CONCLUSIONS: Daily consumption of 3 portions of whole-grain foods can significantly reduce cardiovascular disease risk in middle-aged people mainly through blood pressure-lowering mechanisms. The observed decrease in systolic blood pressure could decrease the incidence of coronary artery disease and stroke by ≥15% and 25%, respectively. This trial was registered at clinicaltrials.gov as ISRCTN27657880.