Very Low Fat Diets
Very Low Fat Diets
Conclusions: There is overwhelming evidence that reductions in saturated fat, dietary cholesterol, and weight offer the most effective dietary strategies for reducing total cholesterol, LDL-C levels, and cardiovascular risk. Decreases in saturated fat should come at the expense of total fat because there is no biological requirement for saturated fat. Essential fatty acids can be adequately derived from unsaturated sources even if total fat intake is ,15% of calories, but the appropriate types and amounts of these dietary fat sources must be selected (ie, highly polyunsaturated vegetable oils). Results from a few clinical trials suggest that very low fat diets are associated with reduced risk of cardiovascular disease, but numerous unanswered questions remain that make population-wide recommendations of such diets premature. Very low fat diets in the short term increase TG levels and decrease HDL-C levels without yielding additional decreases in LDL-C levels. The weight loss that may accompany such diets attenuates these adverse effects on plasma lipid levels. Because long-term results are not available to support the value of very low fat diets to either facilitate continued weight loss or further lower blood cholesterol levels, concerns about their widespread use remain. For certain persons, ie, those with hypertriglyceridemia or hyperinsulinemia, the elderly, or the very young, the potential for elevated TG levels, decreased HDL-C levels, or nutrient inadequacy must be considered. Responses to any dietary intervention designed to alter blood lipid levels or body weight vary among individuals. Data are still lacking from randomized clinical trials in which representative population samples with adequate power were used to test whether there is substantial additional benefit to be derived from very low fat diets. Because very low fat diets represent a radical departure from the current prudent dietary guidelines, such diets must be proved both advantageous and safe before national recommendations can be issued. In the interim, a limited group of motivated, high-risk persons with elevated LDL-C levels and/or preexisting cardiovascular disease may benefit from very low fat diets but only with support, careful supervision, and regular follow-up by the healthcare provider. Advice about optimal substitutions of complex carbohydrates for fat while preserving protein intake should be provided with ongoing assessment to ensure adequate long-term intake of micronutrients.
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