Modification of lipoproteins by very low-carbohydrate diets.

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.