Taken in supplement form, and not in a lower-dose multivitamin, the vitamins'
anti-oxidant properties appear to offset the buildup of so-called free radicals
that are believed to damage cells and lead to the debilitating brain disease.
Alzheimer's gradually robs millions of people of their memories and
ultimately of their mental faculties. Roughly 5 million Americans suffer from
the disease, and the risks of developing it increase markedly with age.
The 4,740 participants in the five-year study were aged 65 or older when the
study began in 1995.
In the first phase of the study, 200 cases of Alzheimer's were diagnosed, and
those who had been taking vitamin supplements were at a 78 percent lower risk of
the disease than those who had not. At the end of the study, another 104
participants had developed the disease, and the risk factor was 64 percent lower
among supplement users.
Taking a lower-dose multivitamin or one of the two vitamin supplements taken
alone did not have the protective effect. A vitamin E supplement together with a
multivitamin may provide some benefit, the researchers said.
Vitamin E supplements contain up to 1,000 international units and most
vitamin C supplements between 500 and 1,000 milligrams. The U.S. recommended
daily allowance for vitamin E is 22 international units, and for vitamin C it is
75 to 90 milligrams, said the report, which was published in the Archives of
Neurology.
High-dose vitamin supplements are rarely toxic and could have wide-ranging
health benefits, the report said.
"These results are extremely exciting," study author Peter Zandi of the Johns
Hopkins Bloomberg School of Public Health said. "Our findings suggest that
vitamins E and C may offer protection against Alzheimer's disease when taken
together in the higher doses available from individual supplements."
Zandi cautioned his was an observational study, and a full-scale controlled
trial was needed.
