Health benefits of nuts: potential role of antioxidants

A diet rich in fruits, vegetables and minimally refined cereals is associated with lower risk for chronic degenerative diseases. Since oxidative stress is common in chronic degenerative disease, it has been assumed that dietary antioxidants may explain this protective effect. Every dietary plant contains numerous types of antioxidants with different properties. Many of these antioxidants cooperate in oxidative stress reduction in plants, and we hypothesize that many different antioxidants may also be needed for the proper protection of animal cells. To test this hypothesis, it is useful to identify dietary plants with high total antioxidant content. Several nuts are among the dietary plants with the highest content of total antioxidants. Of the tree nuts, walnuts, pecans and chestnuts have the highest contents of antioxidants. Walnuts contain more than 20 mmol antioxidants per 100 g, mostly in the walnut pellicles. Peanuts (a legume) also contribute significantly to dietary intake of antioxidants. These data are in accordance with our present extended analysis of an earlier report on nut intake and death attributed to various diseases in the Iowa Women's Health Study. We observed that the hazard ratio for total death rates showed a U-shaped association with nut/peanut butter consumption. Hazard ratio was 0.89 (CI = 0.81-0.97) and 0.81 (CI = 0.75-0.88) for nut/peanut butter intake once per week and 1-4 times per week, respectively. Death attributed to cardiovascular and coronary heart diseases showed strong and consistent reductions with increasing nut/peanut butter consumption. Further studies are needed to clarify whether antioxidants contribute to this apparent beneficial health effect of nuts.