Original Research Effects of Diets High in Walnuts and Flax Oil on Hemodynamic Responses to Stress and Vascular Endothelial Function

resistance, omega-3 fatty acids Background: Polyunsaturated fatty acids (PUFA) have beneficial effects on cardiovascular risk, although the mechanisms are incompletely understood. In a previous article, we showed significant reductions in low-density lipoprotein cholesterol and several markers of inflammation with increasing intake of alpha-linolenic acid (ALA) from walnuts and flax. Objective: To examine effects of ALA on cardiovascular responses to acute stress, flow-mediated dilation (FMD) of the brachial artery, and blood concentrations of endothelin-1 and arginine-vasopressin (AVP). Design: Using a randomized, crossover study design, cardiovascular responses to acute stress were assessed in 20 hypercholesterolemic subjects, a subset of whom also underwent FMD testing (n 5 12). Participants were fed an average American diet (AAD) and 2 experimental diets that varied in the amount of ALA and linoleic acid (LA) that they contained. The AAD provided 8.7 % energy from PUFA (7.7 % LA, 0.8 % ALA). On the LA diet, saturated fat was reduced, and PUFA from walnuts and walnut oil provided 16.4 % of energy (12.6 % LA, 3.6 % ALA). On the ALA diet, walnuts, walnut oil, and flax oil provided 17 % energy from PUFA (10.5 % LA, 6.5 % ALA). Results: The ALA and LA diets significantly reduced diastolic blood pressure (22 to 23 mm Hg) and tota