The nuts are a healthy saturated fat that should be part of the daily diet of anyone who is already more likely to suffer from heart disease, such as an obese person.
Researchers from Penn State University gave 45 overweight or obese participants three different diets: some ate the whole nuts for two weeks, a second group was given a diet rich in ALA—alpha-linolenic acid, an omega-3 fatty acid—that is in walnuts, and the third ate similar quantities of oleic acid, which is also found in walnuts.
Although each group saw some drop in their blood pressure, those who ate the nuts had the most dramatic decrease.
This suggests that there's something about the nuts themselves, rather than just their constituent parts, that work synergistically to improve heart health. "There's a little something extra in walnuts that are beneficial that you don't get in fatty acids alone," said researcher Penny Kris-Etherton.