The Health-E Vitamin

Vitamin E, an essential antioxidant nutrient that occurs naturally in many grains—and their oils—nuts, fruits and in animal fats, helps the human body maintain cell integrity, and protects vitamin A and essential fatty acids from oxidation. Vitamin E generally refers to a family of related molecules known as tocopherols and their near molecular relatives, the tocotrienols, but the alpha-tocopherol form is the most biologically active.

By the numbers

Commercial vitamin E can be extracted from vegetable sources (“natural”) or synthesized, and the different forms exhibit different biological activity. Vitamin E activity is measured in International Units (IU). One IU is equivalent to 1 mg of alpha-tocopherol. The other forms exhibit some bio-potency, although to a lesser degree than the alpha form. The differences in the molecular structures of natural and synthetic vitamin E affect their biological availability. Research suggests that the body actually absorbs natural and synthetic vitamin E at the same rate, but after absorption, the liver preferentially retains the natural d-alpha-tocopherol over the synthetic form. “In terms of labeling for Daily Value, or DV, FDA/USP recognizes natural vitamin E is 1.5 times more potent than the synthetic. In other words, only 20 mg natural vitamin E is needed compared to 30 mg synthetic vitamin E to make the 100% DV claim,” says David Cai, Ph.D., research manager/principle scientist, Cognis Nutrition & Health, LaGrange, IL. “The U.S. National Academy of Sciences has officially recognized that natural vitamin E is twice as potent and retained twice as well as synthetic. This means that twice as much natural vitamin E reaches the blood and organs compared to synthetic.

“For vitamin E, the new DRI (Dietary Reference Intakes, the most recent set of dietary recommendations established by the Food and Nutrition Board of the Institute of Medicine) is set at 15 mg as d-alpha-tocopherols,” Cai continues. This takes a level of 22 IU of the natural form, d-alpha-tocopherol, or 33 IU of the synthetic form, d,l-alpha-tocopherol.

However, Cai notes, “For delivering much-needed health benefits, the recommended intake may have to be higher. Scientists at the Linus Pauling Institute of Oregon State University recommended a supplement providing 200 IU of natural source d-alpha-tocopherol daily, or 400 IU of d-alpha-tocopherol every other day, with a meal, may help protect adults from chronic diseases like heart disease, stroke, neurodegenerative diseases and some types of cancer.”

The average American adult consumes approximately 8 to 12 mg vitamin E per day through a normal diet. Although this is below the RDI, obvious vitamin E deficiency and its resulting nerve damage is rare in healthy individuals, but it may be a concern for those with certain conditions:

• Those unable to absorb dietary fat due to an inability to secrete bile or because of rare disorders of fat metabolism;

• People with rare genetic abnormalities in the alpha-tocopherol transfer; and

• Premature infants with birth weights less than 3 lbs., 4 ozs.

An Institute of Medicine (IOM) report on vitamin E, published in 2000, states that current vitamin E intake estimates might not reflect the actual levels, because energy and fat intake are often underreported in national surveys, and the type and amount of fat added during cooking is often unknown. However, the IOM warns, “Low-fat diets can substantially decrease vitamin E intakes if food choices are not carefully made to enhance a-tocopherol intakes.”

Too much of a good thing

As a fat-soluble vitamin, excess intake of vitamin E is not excreted in the urine. The Food and Nutrition Board of the Institute of Medicine set vitamin E’s upper tolerable intake level (UL) at 1,000 mg (1,500 IU) for supplementary alpha-tocopherol per day (less for children). Because vitamin E can act as an anticoagulant and may increase the risk of bleeding problems, based on animal studies, this is the highest dose unlikely to result in bleeding problems.

Vitamin E safety fell under heightened scrutiny when a 2004 meta-analysis from Johns Hopkins Medical Institutions (“Meta-Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality,” E. Miller, et al, Annals of Internal Medicine, January 2005, Vol. 142, No. 1, 37-46) concluded that long-term high doses of vitamin E (more than 400 IU a day) might increase the overall risk of dying by about 4%. However, lower doses of vitamin E (200 IU or less) did not increase the risk. Three other meta-analyses on vitamin E found no increased risk, and several experts pointed out some potential flaws in the study, including the large population of elderly persons suffering chronic diseases that was used.

Herb Woolf, Ph.D., senior nutritionist, human nutrition group, BASF Corporation, Florham Park, NJ, does not advise fortification above the DRI guideline “unless the particular intended use is well documented for a specific market segment being addressed by the product.” Not only does this avoid potential deleterious effects on the body, he notes the lower levels result in better food and beverage products. “Higher levels of vitamin E use in a beverage formulation would begin to adversely affect clarity in appearance and mouthfeel,” he points out. He says powdered forms of vitamin E at typical use levels in low-moisture applications, such as nutrient bars, do not affect mouthfeel, appearance and texture.

There is evidence that consumption of vitamin E in levels higher than specified by the RDI can help to prevent serious disease. But recent studies suggest the benefits don’t continue to rise with the dose. As in foods, vitamin E’s ability to act as an antioxidant provides the key to the reported health benefits. Vitamin E is believed to counteract oxidative degeneration of cells, which research links to a host of ills, including those mentioned above. Researchers also believe that vitamin E stimulates the immune response and lessens the severity of disorders such as inflammation, premenstrual syndrome and circulatory irregularities. It inhibits the conversion of nitrites to nitrosoamines, strong carcinogens, in the stomach.

The other tocopherols might aid health, too. “Research suggests that non-alpha-tocopherols may be involved in maintaining health,” says Brent Flickinger, Ph.D., senior research manager, Nutritional Science ADM Research, ADM, Decatur, IL. Over the past several years, studies have been published showing that consumption of non-alpha-tocopherols may be related to the health of the nervous system and cardiovascular system, and that greater combined serum levels of gamma-tocopherol and alpha-tocopherol may be impactful for men’s health.”