We share Dr. Ornish's concerns that neither the conventional low-fat diet nor the low-carbohydrate diet in our study reduced total or LDL cholesterol levels. The scientific evidence that aggressive LDL cholesterol lowering reduces atherosclerosis and ischemic coronary events is strong, although complicated by concomitant beneficial effects on inflammatory markers such as C-reactive protein. The evolving data regarding the long-term benefits of increasing HDL cholesterol levels and lowering triglyceride levels, at least by pharmacologic means, are also promising with regard to impact on coronary heart disease (1). Moreover, abnormal levels of HDL cholesterol and triglycerides are core features of the metabolic syndrome, which has been strongly associated with atherosclerosis (2). Nevertheless, we agree that extrapolation of these findings to dietary effects on HDL cholesterol may be complicated by unknown effects on reverse cholesterol transport.

The referenced study of patients following an extremely low-fat diet (3) provided important preliminary findings regarding favorable effects of this diet on LDL cholesterol levels and coronary artery disease. However, this study was also limited by its small size (40 patients) and by uncontrolled confounding variables, such as limiting counseling on exercise, smoking cessation, and stress management to the experimental group. The experimental group also lost more weight. In contrast, a much larger study of 423 patients following a Mediterranean diet that did not severely restrict fat decreased long-term cardiovascular event rates (4). In truth, we still do not know the ideal dietary composition to prevent cardiovascular disease and increase weight loss. A focus on fat restriction that results in excessive refined carbohydrate intake would be expected to exacerbate features of the metabolic syndrome and thus may increase cardiovascular risk. We hope the available studies show that the ideal goals of dietary modification should be to reduce LDL cholesterol levels and improve features of the metabolic syndrome. A diet that helps attain either of these goals merits further investigation to determine its impact on long-term cardiovascular outcomes.

We also want to clarify that the patient in our study with an ischemic cardiomyopathy already had this condition before enrollment, as stated in the manuscript.