Vitamin E is the collective term including four fat- soluble, natural compounds with similar chemical structure; alpha-, beta-, gamma-, and delta-tocopherol. Of these, alpha-tocopherol has the highest nutritional activity. Eight structural isomers of alpha-tocopherol are possible, but only the d-alpha-tocopherol (RRR- alpha-tocopherol) occurs in nature. The other seven isomers have less nutritional activity, and are present only in synthetic vitamin E (dl-alpha-tocopherol) Douglas Laboratories’ Nutri E-400 Forte softgels contain only natural isomers of vitamin E, including d- alpha, d-beta, d-gamma, and d-delta tocopherols. While the d-alpha isomer is the most well-known form of vitamin E, recent scientific evidence indicates that gamma-tochoperol may possess unique, distinguishable features. This tocopherol is the major form of vitamin E in seeds and in the US diet, though has not been studied as broadly as has alpha- tocopherol. Numerous studies have shown gamma- tocopherol to have excellent antioxidant abilities that complements the antioxidant ability of alpha- tocopherol. Additionally, some studies have shown that high dose supplementation of alpha-tocopherols can deplete both plasma and tissue levels of gamma- tocopherol in the body. Vitamin E is one of the body's most important antioxidant nutrients. Antioxidants protect healthy cells from oxidative and free radical damage. Free radicals are unstable chemicals formed in the body during metabolism and from exposure to environmental sources, such as pollution and cigarette smoke. Free radicals are necessary for energy metabolism and immune function, but when an excessive number of free radicals are formed, they can attack healthy cells, especially cell membrane lipids and proteins. This, in turn, is thought to contribute to a number of degenerative diseases. Vitamin E is an especially valuable antioxidant in the cell membranes, where it prevents oxidation of unsaturated fatty acids by trapping free radicals. This helps stabilize and protect cell membranes, especially red blood cells and tissues sensitive to oxidation, such as the lungs, eyes, and arteries. Vitamin E also protects the liver and other tissues from the free-radical damage of toxicants, such as mercury, lead, ozone, nitrous oxide, carbon tetrachloride, benzene, cresol, and various drugs. Related to its antioxidant properties, vitamin E is important for normal immune function, and many studies show that it prevents lipid peroxidation of blood lipoproteins, such as LDL-cholesterol. Nutri E-400 Forte is different from most mixed tocopherols products because it contains natural mixed tocopherols with a minimum guaranteed amount of the d-beta, d-gamma and d-delta tocopherols. Studies have shown that these natural isomers may have added synergistic effects in conjunction with the more commonly used d-alpha tocopherol.