Serum lipoproteins of healthy persons fed a low-fat diet or a polyunsaturated fat diet for three months: A comparison of two cholesterol-lowering diets

Abstract

In a controlled 16-week trial we have compared the effects on some risk factors for atherosclerosis of 2 cholesterol-lowering diets, one low in total fat and low in polyunsaturated fat (LO) and one moderate in total fat but high in polyunsaturated fat (MOD) as recommended by various advisory councils. All 35 volunteers were given diet MOD during a 2.5-week control period. This diet provided 31% of the daily energy intake (energy%) as total fat; one-third of the fatty acids were polyunsaturated (PUFA). VLDL plus LDL cholesterol decreased by 0.66 mmol/1 during the control period while the HDL cholesterol (HDL-C) level was unchanged. Total serum triglycerides decreased by 0.33 mmol/l. After the control period the subjects were randomized into 2 groups, one of which continued on diet MOD, while the other group received the low-fat diet LO, providing 2.1 energy% as total fat and 4 energy% as PUFA. All food was prepared daily and weighed out for each individual in amounts appropriate to the individual's energy needs. Nutrient intakes were checked by 7-day records and by chemical analysis of double portions. The diets contained the same amounts of cholesterol, phytosterols, oligosaccharides and other nutrients known to affect serum lipid levels. Total serum cholesterol increased by 0.21 ± 0.41 mmol/l on control diet MOD during the test period of 13 weeks. 0.09 ± 0.11 mmol/l of this was due to HDL-C. Total serum triglycerides remained constant during the test period in group MOD. On diet LO total serum cholesterol remained stable during the test period, but HDL-C was lowered by −0.06 ± 0.20 mmol/1. The difference in HDL-C between the diet groups was mainly located in HDL₂. Total serum triglycerides increased by +0.32 ± 0.31 mmol/l in group LO; the increase in VLDL triglycerides was +0.22 ± 0.18 mmol/l. The depression of HDL on diet LO was also reflected in the ratio of HDL to total cholesterol which decreased by −0.02 ± 0.05 on diet LO, and was unchanged on diet MOD, and in the ratio of apo A1 to apo B (6% decrease on diet LO and constant on diet MOD). Combination of these data with those from a preceding study [Brussaard et al., Atherosclerosis, 36 (1980) 515] leads to the following conclusions: 1.(1) Both diets lower total serum cholesterol levels when compared with the habitual diets of affluent communities. 2.(2) The high-carbohydrate, low-fat diet causes lower HDL and higher fasting VLDL triglyceride levels than the recommended moderate-fat-high-PUFA diet.