In a new study published in the New England Journal of Medicine, investigators from the Harvard School of Public Health report that women who ate diets relatively low in carbohydrates (and thus relatively high in fats) experienced no increase in coronary artery disease.
These results came from a new analysis of data from the Nurses' Health Study, in which the risk of developing coronary artery disease over a 20 year period was compared to the consumption of fats, carbohydrates and protein in nearly 83,000 women. The chief finding of this analysis was that women who consumed low-fat diets - the kind of heart-protective diet generally recommended by cardiologists - did not have a lower incidence of coronary artery disease than women who consumed low-carb diets. In fact, women on low-carb diets whose fat consumption came mainly from vegetable sources instead of animal sources showed a reduced incidence of heart disease. And women on low-fat diets who consumed carbohydrates with a relatively high glycemic score (that is, carbohydrates that are rapidly absorbed and cause blood glucose elevations) experienced a higher incidence of heart disease.
The carbohydrate "restriction" exhibited by women in this study (who were not following any particular diet) was in the range of 30% of their daily caloric intake, not nearly as restrictive as in the classic Atkins or even the South Beach diet. Also, on average, women in this study low-carb diets did not end up weighing less (or more) than women on low-fat diets.
This is yet another study that calls into question the conventional wisdom that restricted fat diets are a good means to prevent heart disease. It is a retrospective study that is based on questionnaires, however, and does not really prove anything. But it is one more piece of evidence suggesting that certain kinds of low-carb diets - ones that rely on vegetable fats more than animal fats - may be heart healthy, whether or not they produce weight loss.
Halton TL, Willett WC, Liu S et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. N Engl J Med 2006; 355:1991-2002.