Modification lipoproteins by very low-carb diets

Thumbs-up to prof. Volek (Human Performance Lab, University of Connecticut). A man who always speaks his mind without any fear of demigods, aka medical community.

Volek JS, Sharman MJ, Forsythe CE. Modification of lipoproteins by very low-carbohydrate diets. J Nutr. 2005;135(6):1339-42.

ABSTRACT

Very low-carbohydrate diets (VLCDs) are popular, but remain controversial. This review summarizes the latest studies that have examined the effects of VLCDs on lipoproteins and related risk factors for cardiovascular disease. Prospective studies indicate that VLCDs improve the lipoprotein profile independently of weight loss. Although not as effective at lowering LDL cholesterol (LDL-C), VLCDs consistently improve postabsorptive and postprandial triacylglycerols (TAGs), HDL cholesterol (HDL-C), and the distribution of LDL-C subfractions to a greater extent than low-fat diets. VLCDs also improve proinflammatory markers when associated with weight loss. Studies usually report mean lipid responses, but individual data indicate a large degree of variability in the magnitude and in some cases the direction (e.g., LDL-C) of lipoprotein responses to both low-fat and VLCDs. Such variability makes it hard to defend a single diet recommendation, especially considering the potential for low-fat/high-carbohydrate diets to exacerbate TAG, HDL-C, and other characteristics of the metabolic syndrome. Considering the effectiveness of VLCDs in promoting fat loss and improving the metabolic syndrome, discounting or condemning their use is unjustified. We encourage a more unbiased, balanced appraisal of VLCDs.

KEY WORDS: • cholesterol • low-carbohydrate diet • ketogenic • triglycerides • lipoproteins

The aim of this review is to acquaint the reader with the resurgence of scientific papers published recently examining the effects of very low-carbohydrate diets (VLCDs)(3) on blood lipoproteins and cardiovascular disease (CVD) risk factors. Despite the number of papers and the consistency of the results, most health practitioners including dietitians are unaware or misinformed on the topic and remain cautious about using VLCDs. VLCDs are discouraged by most professional organizations (1,2) because they contradict low-fat diets. This review will address whether it is reasonable to consider VLCDs as a dietary option with respect to outcomes related to CVD risk.

Despite government and medical disapproval of carbohydrate restriction, physicians personally use VLCDs at least as much as low-fat diets (3). Surveys indicate that millions of Americans are attempting to limit carbohydrate intake and the best-selling lay diet books have consistently focused on carbohydrate restriction. Interest in VLCDs among the scientific community has lagged behind the public. No formal definition of VLCDs exists, but arbitrary levels are defined as <50 g carbohydrate/d or <10% of total energy (4). Most VLCD studies do not control the amount of cholesterol, fiber, or quality of nutrients (e.g., type of fat). This is important because the effects could be enhanced further if, for example, a VLCD were combined with exercise or fiber-rich foods. Food choices compatible with this level of carbohydrate restriction (e.g., vegetables, beef, poultry, fish, oils, nuts/seeds, salads, cheese) generally result in an intake of 60–65% fat and 20–25% protein. Nearly all VLCD studies are among free-living subjects; thus actual intakes are variable and dependent on subject preference and compliance. A major point is that VLCDs differ dramatically from current recommendations, and this fact has unnerved many people in the nutrition community.

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