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No CHD Risk Increase or Reduction with a Low-Carb Diet in Women

Nurses’ Health Study data suggest that the carbohydrate content of a diet is neither an independent risk factor for, nor a protector from, coronary heart disease.

Low-carbohydrate diets are popular, but their long-term safety has not been well studied. To address this knowledge gap, investigators evaluated the relation between diet and outcomes among 82,802 participants in the longitudinal, prospective Nurses' Health Study. Using a scoring system they developed, the investigators classified the participants’ diets into deciles of carbohydrate content (i.e., relative to fat and protein content). Daily mean carbohydrate intake ranged from 117 g to 234 g across the deciles.

Among a subgroup of 466 women from whom blood samples were drawn, carbohydrate scores were not associated with baseline total-, HDL-, or LDL-cholesterol levels in a multivariable analysis. Scores also were not associated with risk for coronary heart disease during 20 years of follow-up (1,584,042 person-years). Findings did not vary by body-mass index, physical activity, smoking status, diabetes status, hypertension, or high cholesterol. However, moderately increased risk for CHD was significantly associated with greater glycemic load in diets and nearly significantly with greater total carbohydrate intake (as distinct from the carbohydrate content of diets, measured by the scoring system).

Comment: In this large epidemiologic study of women, a low-carbohydrate diet (i.e., with fewer carbs relative to fat and protein) was not found to be a CHD risk factor, nor was it found to protect against CHD. The findings should allay some concerns that low-carbohydrate diets increase risk for CHD. Notably, though, this study was about diet constituents, not dieting per se; therefore, the findings do not have direct implications for people who are trying various weight-loss strategies.

— Harlan M. Krumholz, MD, SM

Published in Journal Watch Cardiology November 8, 2006

Citation(s):

Halton TL et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. N Engl J Med 2006 Nov 9; 355:1991-2002.

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