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Extra Vitamin E May Thwart Infections in the ElderlyBy Judy McBride
May 6, 1997
WASHINGTON, May 6--An extra 200 milligrams of vitamin E every day can go a long way toward reducing infections and potential cancers in older people, according to findings of a U.S. Department of Agriculture study to be published tomorrow (May 7) in the Journal of the American Medical Association.
Men and women over age 65 who took daily vitamin E supplements had clinically relevant improvements in their immune system's response to foreign antigens, substances that cause the body to produce antibodies. Those getting the 200-milligram dose--equivalent to 200 International Units (I.U.)--had the strongest responses, said study leader Simin Nikbin Meydani.
The ability of vitamin E to boost a flagging immune system is further supported by an animal study that Meydani and colleagues are reporting in the July issue of Journal of Infectious Diseases. Older mice that received high doses of vitamin E suppressed the influenza virus far better than their counterparts getting the recommended level of vitamin.
"Together, these findings give hope for reducing infections and possibly cancer in the elderly," said USDA Undersecretary for Research, Education and Economics Cathie Woteki. "It's well established that the immune system declines with aging, contributing to an increase in infections and cancer rates. Until now, very few nutritional interventions have enhanced the immune response of older people."
Eighty men and women participated in the six-month study at the USDA Human Nutrition Research Center on Aging at Tufts in Boston. Meydani, a nutritionist and immunologist, and colleagues divided the volunteers into four groups to test three different levels of vitamin E--60, 200 or 800 milligrams--versus a placebo.
"It surprised us that 200 milligrams of vitamin E was the optimal level, not 800 milligrams," said Meydani, who had earlier tested the higher dose on elders with positive results. "Even those taking 60 milligrams daily had improvements in some tests."
Each person who received vitamin E was given a DTH skin test, in which seven antigens are injected into the skin. The group taking 200 milligrams of vitamin E had a stronger response to the test than the other two supplemented groups, Meydani said, although the difference wasn't statistically significant.
"The DTH test measures the body's reaction to the antigens," she explained. "It indicates how well T cells remember antigens they have seen before and how to respond to them."
Compared with the placebo group, the volunteers taking 200 milligrams of vitamin E daily had a 65 percent increase in DTH response. Those taking 800 milligrams had a 49 percent increase.
The 200-milligram group also produced the highest levels of antibodies against three vaccines. For example, their antibodies to hepatitis B virus were six times greater than the placebo group, compared with 2.5 times greater in the 800-milligram group.
"It appears that 200 milligrams was a threshold level for these volunteers," Meydani noted. "They got no added benefit from taking more."
The researchers also ran tests to see if supplemental vitamin E prompted the volunteers to produce antibodies against their own proteins, which can lead to autoimmune diseases such as rheumatoid arthritis. They did not, Meydani said, adding that no side effects were seen from taking the extra vitamin E.
Good food sources of vitamin E include nuts, seeds, whole grains, fortified cereals, vegetable oils, margarine, seafoods, liver and leafy green vegetables.
Scientific contact: Simin Nikbin Meydani, DVM, PhD, chief, Nutritional Immunology Laboratory, USDA Human Nutrition Research Center on Aging at Tufts, Boston, Mass. 02111, phone (617) 556-3129, fax 556-3224, e-mail firstname.lastname@example.org.
Until 12 noon May 7, Dr. Meydani can be reached at the Emory Conference Center Hotel, Atlanta, Ga., phone (404) 712-6000, room 4412.