The effect of a low-fat, high-carbohydrate diet on serum high density lipoprotein cholesterol and triglyceride

Abstract

Objective: To determine whether substituting carbohydrate for saturated fat has any adverse effects on serum high density lipoprotein (HDL) cholesterol and triglycerides in free-living individuals. Design: Randomised crossover trial. Setting: General community. Subjects: Volunteer sample of 38 healthy free-living men with mean (s.d.) age 37 (7) y, moderately elevated serum total cholesterol 5.51 (0.93) mmolal and body mass index 26.0 (3.6) kgam 2 . Interventions: Participants completed two six week experimental periods during which they consumed either a traditional Western diet (36%, 18%, and 43% energy from total, saturated, and carbohydrate, respectively) or a low-saturated fat high-carbohydrate diet (22%, 6% and 59% energy from total, saturated, and carbohydrate, respectively). Dietary principles were reinforced regularly, but food choices were self-selected during each experimental period. Main outcome measures: Serum lipids, body weight and plasma fatty acids. Results: Reported energy and nutrient intakes, plasma fatty acids, and a drop in weight from 79.1 (12.5) kg on the Western diet to 77.6 (12.0) kg on the high-carbohydrate diet (P`0.001) con®rmed a high level of compliance with experimental diets. Total and low density lipoprotein (LDL) cholesterol fell from 5.52 (1.04) mmolal and 3.64 (0.88) mmolal, respectively on the Western diet to 4.76 (1.10) mmolal and 2.97 (0.94) mmolal on the high-carbohydrate diet (P`0.001). HDL cholesterol fell from 1.21 (0.27) mmolal on the Western diet to 1.07 (0.23) mmolal on the high-carbohydrate diet (P 0.057), but the LDL:HDL cholesterol ratio improved from 3.17 (1.05) on the Western diet to 2.88 (0.97) on the high-carbohydrate diet (P 0.004). Fasting triglyceride levels were unchanged throughout the study. Conclusions: Replacement of saturated fat with carbohydrate from grains, vegetables, legumes, and fruit reduces total and LDL cholesterol with only a minor effect on HDL cholesterol and triglyceride. It seems that when free living individuals change to a ®bre rich high-carbohydrate diet appropriate food choices lead to a modest weight reduction. This may explain why the marked elevation of triglyceride and reduction of HDL cholesterol observed on strictly controlled high-carbohydrate diets may not occur when such diets are followed in practice.

Long-term calorie restriction is highly effective in reducing the risk for atherosclerosis in humans

“…The Biospherians' largely vegetarian diet was very low in fat (Ϸ10% of energy intake) and high in carbohydrate (Ϸ76% of energy intake), with protein supplying Ϸ14% of energy intake. It is well documented that energy-restricted high-carbohydrate diets result in a decrease in HDL-C (18). In contrast, the CR group in the present study restricted their carbohydrate intake to, on average, 46% of energy intake.…”

Dietary carbohydrate: relationship to cardiovascular disease and disorders of carbohydrate metabolism

“…In studies of free living individuals in whom fruits, vegetables and legumes rich in the viscous forms of NSPs replaced some of the relatively high fat foods typically consumed in a western diet, total and LDL cholesterol fell as expected, and the ratio of total (or LDL) cholesterol to HDL cholesterol improved with no change reported in triglyceride despite an appreciable increase in total carbohydrate (Turley et al, 1998). Total carbohydrate provided 59 and 43% total energy on the high and low carbohydrate diets.…”

Optimal macronutrient balance

“…Consequently it is argued that the level of dietary fat should not be the focus of reduction, but rather the level of cholesterol-raising SFA should be the central public health nutrition message. Two recent studies (Saris et al 1998;Turley et al 1998) have failed to demonstrate a rise in plasma TAG and a fall in plasma HDL-cholesterol with low-fat high-carbohydrate diets. Turley et al (1998) rotated thirty-eight healthy subjects through a standard Western-type diet (36 % energy from fat, 43 % energy from carbohydrate) and a highcarbohydrate diet (22 % energy from fat, 59 % energy from carbohydrate), with the subjects given advice on how to select a low-fat high-carbohydrate diet.…”

“…It may be that the initial level of plasma TAG is of importance. In the study of Turley et al (1998) and in the CARMEN study (W Saris, personal communication) fasting plasma TAG levels were 1·41 and 1·60 mmol/l respectively. However, in the case of Roche & Gibney (1996) and Mensink & Katan (1987), where low-fat high-carbohydrate diets significantly elevated plasma TAG levels, the fasting plasma TAG levels were much lower (0·95 and 0·86 mmol/l respectively).…”