Objective: Two dietary regimens recommended for the reduction of coronary risk, by way of their effects on lipid profile, are the diet low in saturated fat and a diet rich in monounsaturated fats (MUFA). However the effects of these diets on carbohydrate metabolism in healthy subjects are not well known. The objective of this study was to compare the effect of both diets on various parameters of carbohydrate metabolism.
Methods: 41 healthy young males were submitted to 3 consecutive diets, each for a duration of 4 weeks. The first diet was rich in saturated fat (SAT) (38% fat, 20% saturated). The second was rich in carbohydrates following the recommendations of the NCEP-I (National Cholesterol Education Program type I) (28% fat, 47% carbohydrates). The last one was a diet rich in monounsaturated fatty acids (38% fat, 22% MUFA). At the end of each dietary period, blood pressure (BP) and blood levels of glucose, insulin and free fatty acids were determined. 29 subjects were also submitted to an oral glucose tolerance test (OGTT) at the end of each diet.
Results: The SAT diet induced the highest levels of insulin after the OGTT. The consumption of the MUFA diet determined the lowest levels of fasting blood glucose (-0.60 mmol/l [13%], p < 0.0002), insulin (-9 microUl/ml [47%], p < 0.0002) and free fatty acids (-0.11 mmol/l [24%], p = 0.006), compared to the NCEP-I diet. Systolic and diastolic blood pressure were higher in the NCEP-I diet than during the other periods (SBP: +6 mmHg compare with SAT [5%], p = 0.0001; and +5 mmHg compare with MUFA [4%], p = 0.0001; DBP: +20 mmHg compare with MUFA [27%], p = 0.0001) and +6 mmHg compared with SAT [8%], p = 0.0001).
Conclusion: Of the diets most commonly used for the treatment and prevention of arteriosclerosis, a diet rich in monounsaturated fats is the most beneficial for the healthy population from the point of view of carbohydrate metabolism and blood pressure.