Effects on blood pressure, glucose, and lipid levels of a high-monounsaturated fat diet compared with a high-carbohydrate diet in NIDDM subjects.

OBJECTIVE: To compare the influence on blood pressure, glucose, and lipid levels of a diet rich in monounsaturated fatty acids with an isocaloric, high-carbohydrate diet in 15 NIDDM subjects.

RESEARCH DESIGN AND METHODS: A crossover design with diet interventions and wash-out periods of 3 wk was applied. The patients were randomly assigned to a 3-wk treatment with a high-carbohydrate diet containing 50% of energy as carbohydrate and 30% of energy as fat (10% of energy as monounsaturated fatty acids) or an isocaloric diet with 30% of energy as carbohydrate and 50% of energy as fat (30% of energy as monounsaturated fatty acids). On the last day of the two diets, 24-h ambulatory blood pressure was measured and day profiles of glucose, hormones, and lipids were performed to a test menu rich in carbohydrates.

RESULTS: The diet rich in monounsaturated fat reduced daytime systolic (131 +/- 3 vs. 137 +/- 3 mmHg, P < 0.04) and 24-h systolic blood pressure (126 +/- 8 vs. 130 +/- 10 mmHg, P < 0.03) as well as daytime diastolic (78 +/- 2 vs. 84 +/- 2 mmHg, P < 0.02) and diurnal diastolic blood pressure (75 +/- 6 vs. 78 +/- 5 mmHg, P < 0.03) as compared with the high-carbohydrate diet. Evidence of lowered blood glucose levels on the high-monounsaturated diet compared with the high-carbohydrate diet were found with lower fasting blood glucose (6.1 +/- 0.3 vs. 6.8 +/- 0.5 mM, P < 0.05), lower average blood glucose levels (7.4 +/- 0.5 vs. 8.2 +/- 0.6 mM, P < 0.04), and peak blood glucose responses (9.9 +/- 0.6 vs. 11.3 +/- 0.7 mM, P < 0.02). The two diets had the same impact on lipid levels.

CONCLUSIONS: A diet rich in monounsaturated fat has beneficial effects on blood pressure and glucose metabolism, whereas no adverse effects on lipid composition in NIDDM subjects is detected.