Phytochemical composition of nuts.

Observational studies suggest nut consumption is inversely associated with the incidence of cardiovascular disease and cancer. In addition to being rich in several vitamins and minerals, unsaturated fatty acids, and fiber, tree nuts and peanuts contain numerous phytochemicals that may contribute to promoting health and reducing the risk of chronic disease. While many of these bioactive constituents remain to be fully identified and characterized, broad classes include carotenoids, phenols, and phytosterols. Phytosterols in nuts range from 95-280 mg/100 g. alpha- and beta-Carotene, beta-cryptoxanthin, lutein, and zeaxanthin are found in microg/100 g amounts in some nuts but at 1-3 mg/100 g in pistachios and none at all in Brazils, macadamias, and peanuts. Phenols, including phenolic acids, flavonoids, and stilbenes, are present in nuts. Walnuts are particularly rich in total phenols with 1625 mg gallic acid equivalents/100 g. The stilbene resveratrol is found in peanuts and pistachios at 84 and 115 microg/100 g, respectively. The flavonoid content of nuts as provided in USDA Database for the Flavonoid Content of Selected Foods, lists totals in pecans at 34, almonds at 15, and pistachios and hazelnuts at 12 mg/100 g. Proanthocyanidins are found in almonds, cashews, hazelnuts, pecans, pistachios, peanuts, and walnuts, with concentrations varying from 9-494 mg/100 g. Nut phytochemicals have been associated with numerous bioactivities known to affect the initiation and progression of several pathogenic processes. However, as complete phytochemical profiles are lacking for most nuts, information is limited regarding their bioavailability and metabolism, so further research on this topic is warranted.