A prospective randomised trial to determine the efficacy of a low glycaemic index diet given in addition to healthy eating and weight loss advice in patients with coronary heart disease

Objective: Recent epidemiological and prospective trial evidence suggests that consumption of a low glycaemic index (LGI) diet will reduce coronary risk. We hypothesise that introduction of an LGI diet will improve the metabolic profile of patients who have undergone coronary artery bypass grafting. Design: We conducted a randomised parallel group trial comparing a control group (n = 29, age 61.8 +/- 9 y), who received currently advocated healthy eating dietary advice only, to an intervention group, who received healthy eating advice emphasising LGI carbohydrates (n = 26, age 63.6 +/- 9.4 y) over a 12-week period in free-living patients with coronary heart disease. Outcome measures included fasting glucose, insulin, total cholesterol, high-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides. Results: A significant lower dietary glycaemic index was achieved in the group assigned to an LGI diet compared to the healthy eating control group (71 +/- 1 vs 81 +/- 1); fibre intake was also higher in the LGI group (20 +/- 1 vs 15 +/- 1 g). All biochemical markers of glucose and lipid metabolism measured were similar after 12 weeks of the LGI diet or control diet. Discussion: The LGI group achieved a significant LGI and a higher dietary fibre intake. However, there was no measurable significant effect of either the LGI diet or the health eating diet on lipid levels; this may have been hidden by concurrent drug therapy.