The Greatest of E's

Vitamin E serves as both a human nutrient and a food-product antioxidant. The science supporting preservative effects is fairly well established. However, many unknowns regarding its function in the body still exist. Researchers are helping industry gain a better understanding of vitamin E's role and its health benefits to an aging population.

In May, at the New York Academy of Sciences symposium, "Vitamin E and Health," researchers shared recent findings about this family of fat-soluble vitamins: how different forms of vitamin E are metabolized, which forms the body prefers and how the liver absorbs vitamin E. What still puzzles them, however, is exactly what vitamin E does in the body -- and how. (For more information on the meeting, visit www.nyas.org).

"Vitamin E is widely acknowledged as a powerful antioxidant and this conference reminds us of its important role in human health," says Kathleen Moran, global market segment manager, dietary supplements, Cognis Nutrition & Health, LaGrange, IL, cosponsors of the conference.

The food industry knows vitamin E acts as a natural preservative by preventing oxidation. The question posed at the conference was if vitamin E acts only as an antioxidant in the body, or if it also operates in some other ways.

Scientists have long believed that vitamin E acts as an antioxidant neutralizing toxic byproducts of metabolism. But recent discoveries suggest that vitamin E molecules act as anti-inflammatory agents, preventing the clumping of platelets. They also regulate gene activity, cell proliferation and the production of important cell-signaling molecules, such as nitric oxide. These actions suggest that vitamin E could help stave off heart disease and atherosclerosis. Symposium attendees suggest that future studies include measurement of subjects' vitamin E concentrations along with biomarkers for oxidative stress or inflammation.

Vitamin E offers many benefits. Data indicates that vitamin E can thwart respiratory infections and the common cold in seniors, slow Alzheimer's disease and prevent preeclampsia in pregnant women. Other studies show it helps maintain a healthy heart and brain function, and it supports eye health and contributes to good health as people age. Trials also are underway to investigate whether it helps prevent prostate cancer.

"Vitamin E is the second-largest-selling supplement in the United States, preceded only by multivitamins, which is why food formulators are very interested in fortifying foods and beverages with vitamin E," says Greg Dodson, product manager, natural health and nutrition, ADM, Decatur, IL.   "What product developers need to realize is that there is a difference between natural and synthetic vitamin E, as natural-sourced vitamin E is absorbed and retained by the body at about double the rate of typical synthetic forms. Many consumers know this and are seeking out foods and beverages fortified with natural vitamin E."

Eight classes of vitamin E, each with different physiological activities, exist. The side-chain structure determines if it is a tocopherol or tocotrienol. Within each of these groups, the number and position of methyl groups in the chromanol ring determines if it is alpha, beta, gamma or delta.

Isomer configurations refer to the direction of the methyl group on the side chain, with only the d-alpha-tocopherol form officially recognized as having biological activity. Natural-sourced vitamin E, extracted from a number of bean, grain and seed oils, exists as a single isomer referred to as d-alpha-tocopherol, which is the only alpha-tocopherol form found in nature. Synthetic-based vitamin E, the dl form, a mixture of d and l, is petroleum-based and contains eight isomers of alpha-tocopherol, with only 12.5% of synthetic vitamin E being the biologically active d-form.

The human body prefers to retain d-alpha-tocopherol in the liver. This is due to a protein called alpha-tocopherol transfer protein, which does not recognize non-d-alpha-tocopherol isomers very well, so the body excretes   these forms.  

For food and beverage applications, d-alpha-tocopherol is available as both a powder and oil. Suppliers often stabilize the free d-alpha-tocopherol by esterification. For example, the esters d-alpha-tocopherol acetate (powder or oil) and d-alpha-tocopherol succinate (powder) have the active hydroxyl group on the chromanol ring at carbon 6 blocked. This protects it from oxidation and prevents loss of vitamin E activity.

Suppliers also offer a mixture of d-alpha, d-beta, d-delta and d-gamma tocopherols. Oftentimes, two versions of "mixed tocopherols" are marketed, one version being "high d-alpha mixed tocopherols," with the system containing more than half d-alpha, and the other being "high non-alpha mixed tocopherols" (d-beta, d-delta and d-gamma).

"The ultimate fortification goal is to produce a formulated food or beverage that provides meaningful nutrition without detracting from its taste or appearance," says Herbert Woolf, technical marketing manager, BASF North America, Florham Park, NJ. "Vitamin E, having little or no flavor, textural impact or color, meets both objectives."

"Mixed tocopherols are excellent free-radical quenchers and retard development of rancidity in foods. High d-alpha-tocopherols have excellent vitamin E activity, but are functionally not as good an antioxidant as high non-alpha-tocopherols. This is because alpha-tocopherol is an antioxidant, and it gets oxidized," says Harry Madeka, technical services manager, DSM Nutritional Products Inc., Parsippany, NJ. "For preservation purposes, the gamma and delta forms are the most active. Thus, mixed tocopherols high in non-alpha tocopherols are typically used to prevent lipid oxidation."

Lipid oxidation occurs when atmospheric oxygen attacks unsaturated fatty acids, producing compounds that negatively affect a food's appearance, odor and taste. The hydroxyl group on vitamin E's chromanol ring donates a hydrogen ion, thus blocking free-radical formation and halting the oxidative process. This extends shelf life.

"Alpha-tocopherol is also a functional antioxidant and can stabilize oxidizable nutrients or constituents, such as flavors or unsaturated oils," adds Woolf. "In addition to alpha-tocopherol or mixed tocopherols, water-soluble antioxidants and metallic chelators can be used synergistically to improve functional antioxidant performance.

"Consideration should also be given to the exposure of foods and beverages to air and ultraviolet and visible light," Woolf says. "The stable nature of vitamin E enables it to endure many food-processing conditions, which might lead to more-widespread use in foods and beverages."

Until recently, manufacturers of clear beverages, such as vitamin waters, iced teas and sports drinks, found including vitamin E challenging, because vitamin E is insoluble in water. "Being a fat-soluble vitamin, when beverage formulators incorporate vitamin E into an    aqueous base, droplets of the vitamin E can rise to the top of the liquid," says Dodson. This is called "ringing."

Cold-water-dispersible forms of natural vitamin E are not suitable for clear beverages, as they cloud the clarity. Soluble vitamin E is great in creamy or opaque beverages. In clear beverages, it dissolves, but yields an opalescent dispersion. New clear, water-soluble forms have been formulated for use in clear beverages, as they do not cloud or ring.

Donna Berry, president of Chicago-based Dairy & Food Communications, Inc., a network of professionals in business-to-business technical and trade communications, has been writing about product development and marketing for 11 years. Prior to that, she worked for Kraft Foods in the natural-cheese division. She has a B.S. in Food Science from the University of Illinois in Urbana-Champaign. She can be reached at [email protected].

Back to top