English walnuts (Juglans regia L.) improve antioxidant capacity in humans

Abstract

The consumption of English walnuts (Juglans regia L.) promotes cardiovascular health, in part due to its favorable effect on serum lipids. Walnut polyphenols, including ellagitannins (ET) may also contribute to this benefit. To determine whether consuming walnuts in amounts readily incorporated into the diet (0.75 and 1.50 oz) has a dose‐response effect on plasma antioxidant capacity, we conducted a randomized, crossover study with a 1 wk run‐in period, 6 wk interventions with each walnut dose, and a 6 wk washout period between these tests in 20 healthy, non‐smoking adults ≥50 y. Subjects followed a low ET diet during the entire 19 wk study, and a low polyphenol diet for 2 d prior to each visit. Walnut intake tended to increase selected measures of plasma antioxidant capacity in a dose‐dependent manner with a higher proportion of responders in the 1.50 vs. 0.75 oz group, particularly in women. These data suggest that walnuts may modestly improve antioxidant capacity in humans, revealing another potential mechanism to further support the FDA qualified health claim that the regular consumption of walnuts decreases the risk of heart disease. (Supported by USDA and California Walnut Commission)