Nutritional advice to increase soluble fibre intake does not change plasma folate or homocysteine in men with angina: a randomised controlled trial

Objective: To study the effect of advice to increase dietary soluble fibre, including fruit and vegetables, on plasma folate and homocysteine in men with angina. Design: Data were collected on a subset of subjects from the Diet and Angina Randomised Trial (DART II). In a randomised (2 × 2) factorial design, subjects received advice on either, neither or both interventions to: (1) increase soluble fibre intake to 8.0 g day−1 (fruit, vegetables and oats); (2) increase oily fish intake to 2 portions week−1. Those who received soluble fibre advice were compared with those who did not. Subjects were genotyped for C677T variant 5,10-methylenetetrahydrofolate reductase (MTHFR). Setting/subjects: Seven hundred and fifty-three male angina patients were recruited from general practice. Results: Plasma homocysteine concentrations were at the upper end of the normal range (median 11.5, 25% 9.4, 75% 14.0 μmol l−1). Baseline intake of fruit and vegetables was positively correlated with plasma folate (rs = 0.29, P < 0.01). Smokers had lower intakes of fruit and vegetables, lower plasma folate and higher homocysteine (all P < 0.01). Homozygotes for variant MTHFR had higher homocysteine concentrations at low plasma folate (P < 0.01). Reported intakes of fruit and vegetables and estimated dietary folate increased in the intervention group (ca. +75 g day−1, P < 0.01 and ca. +20 g day−1, P < 0.05, respectively). However, neither plasma folate (baseline/follow-up 4.5 vs. 4.4 μg l−1, P = 0.40) nor homocysteine (baseline/follow-up 11.7 vs. 11.7 μmol l−1, P = 0.31) changed. Conclusions: Plasma homocysteine, a cardiovascular risk factor, is influenced by MTHFR genotype, plasma folate and smoking status. Dietary advice successfully led to changes in fruit and vegetable intake, but not to changes in plasma folate or homocysteine, possibly because the fruits and vegetables that were chosen were not those richest in folate

Lack of benefit of dietary advice to men with angina: results of a controlled trial

Objective: To see whether mortality among men with angina can be reduced by dietary advice. Design: A randomized controlled factorial trial. Setting: Male patients of general practitioners in south Wales. Subjects: A total of 3114 men under 70 y of age with angina. Interventions: Subjects were randomly allocated to four groups: (1) advised to eat two portions of oily fish each week, or to take three fish oil capsules daily; (2) advised to eat more fruit, vegetables and oats; (3) given both the above types of advice; and (4) given no specific dietary advice. Mortality was ascertained after 3–9 y. Results: Compliance was better with the fish advice than with the fruit advice. All-cause mortality was not reduced by either form of advice, and no other effects were attributable to fruit advice. Risk of cardiac death was higher among subjects advised to take oily fish than among those not so advised; the adjusted hazard ratio was 1.26 (95% confidence interval 1.00, 1.58; P=0.047), and even greater for sudden cardiac death (1.54; 95% CI 1.06, 2.23; P=0.025). The excess risk was largely located among the subgroup given fish oil capsules. There was no evidence that it was due to interactions with medication. Conclusion: Advice to eat more fruit was poorly complied with and had no detectable effect on mortality. Men advised to eat oily fish, and particularly those supplied with fish oil capsules, had a higher risk of cardiac death. This result is unexplained; it may arise from risk compensation or some other effect on patients' or doctors' behaviour. Sponsorship: British Heart Foundation, Seven Seas Limited, Novex Pharma Limited, The Fish Foundation