Phytochemicals in nuts may have antioxidant and antiproliferative activities.

Epidemiological studies have shown that consuming nuts is associated with a reduced risk of cardiovascular disease. Phytochemicals, mainly phenolics and flavonoids, appear to be the major bioactive compounds responsible for the health benefits offered by nuts. However, little is known about the antiproliferative activity of nuts.

Scientists at Cornell University investigated the profiles of total phenolics, including both soluble free and bound forms, the total antioxidant activity, and the antiproliferative activity of nuts commonly consumed in the United States. Ten types of nuts--almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, peanuts, pecans, pine nuts, pistachios and walnuts--were analyzed.

Total antioxidant activities of these nut extracts were determined using the total oxyradicalscavenging capacity (TOSC) assay. The antiproliferative activities on HepG2 human liver cancer cells and Caco-2 human colon cancer cells were measured by assay as well. Walnuts had the highest total phenolic and flavonoid content (1581 [+ or -] 58 and 745 [+ or -] 93 mg per 100 g, respectively). Walnuts also exhibited the highest total antioxidant activity (458 [+ or -] 14 micromole vitamin C equivalent per g of nut), followed by pecans, peanuts, pistachios, cashews, almonds, Brazil nuts, pine nuts, macadamia nuts and hazelnuts.

The proliferation of HepG2 and Caco-2 cancer cells was significantly inhibited in a dose-dependent manner after their exposure to the extracts of walnuts, pecans, peanuts, pine nuts, almonds, macadamia nuts and cashews. Walnuts and pecans exhibited the highest antiproliferative activity against both HepG2 and Caco-2 cells. Both soluble free phenolic and flavonoid content strongly correlated with total antioxidant activity. The research clearly showed that phytochemicals in nuts have potent antioxidant and antiproliferative activities.

Nuts are part of the U.S. Food Guide Pyramid. Experts recommend eating a variety of foods from the five food groups every day in order to get the nutrients you need. The recommended number of servings from this group of foods is two to three per day. One-third of a cup of nuts or two tablespoons of peanut butter is equal to a one-ounce serving of cooked lean meat.

Further information. Rui Hai Liu, Department of Food Science, Cornell University, 108 Stocking Hall, Ithaca, NY 14853; phone: [phone]; fax: [phone]; email: [e-mail].