Several years ago, a scientific report published in the Journal of the American College of Nutrition said that walnut oil improves reaction to stress. It's well known that raw walnuts contain glyceryl triacylates of the n-3 fatty acid alpha-linolenic acid, which is not as effective in humans as long-chain n-3 fatty acids, and (mostly insoluble) antioxidants. Roasting reduces antioxidant quality.
Another study has suggested that consumption of walnut kernels increases fat oxidation and reduces carbohydrate oxidation without any side effects, which suggests that consumption of walnuts may improve the use of body fat in overweight people.
Compared to other nuts, such as peanuts, almonds, and hazelnuts, walnuts contain the highest level of antioxidants.