Jennifer Dearborn, MD

Allison MA, Aragaki A, Eaton C, Li W, Van Horn L, Daviglus ML, and Berger JS. Effect of Dietary Modification on Incident Carotid Artery Disease in Postmenopausal Women: Results From the Women’s Health InitiativeDietary Modification Trial. Stroke. 2014

In this study, a low-fat diet was not linked to a lower incidence of carotid artery disease, associated with stroke. The Women’s Health Initiative Diet Modification Trial randomized 48,835 women to a diet intervention or control based on decreasing fat intake to less than 20% of total calories and increasing intake of fruits, vegetables and whole grains. This same cohort previously examined outcomes of this intervention on incident stroke, and found no difference in rates of ischemic or hemorrhagic stroke in the intervention arm. This study looked at incident carotid disease (of which there were only 277 in the total population), as defined by an overnight hospitalization with coding for symptomatic carotid disease. 

This study may be taken as further evidence that “low fat” may not be better for vascular disease of the brain. Its strength is in its size and scope in a large cohort with rigorously measured confounders. A limitation of the study is that it used hospital based coding to look at symptomatic disease, rather using an imaging marker of plaque progression, such as intima media thickness as an intermediary. Recently, the PREDIMED study showed that a Mediterranean Diet supplemented with nuts was associated with delayed progression of carotid artery intima media thickness and plaque height, as measured by ultrasound. The Mediterranean Diet is not low fat; instead it is replete with olive oil, nuts and “good fats” along with moderate alcohol. These different conclusions may stem from the difference in the dietary intervention studied. This study should encourage us to examine the concept of the “healthy diet” and to better define what this means for vascular disease of the brain. A healthy lifestyle and diet should decrease stroke, right?