MONDAY, Jan. 19, 2004 (HealthDayNews) -- People who load up on antioxidant vitamins may gain protection against Alzheimer's disease later in life, new research suggests.
The study of more than 4,700 men and women in Utah found that those who took extra vitamin E and C were about 60 percent less likely to develop dementia and other memory and thinking problems linked with Alzheimer's as those who didn't use the two supplements.
The effect appeared only in people who combined the two vitamins, however, and neither on its own seemed to offer protection against the brain-wasting disease, which afflicts 4 million Americans.
Peter Zandi, a Johns Hopkins mental health expert and leader of the research, calls the results "intriguing," adding that they "definitely provide a justification for prevention trials, specifically, if possible, for a regimen of vitamin E and vitamin C in combination."
Lab studies indicate that vitamin C, which quickly passes through the body in water, may boost the effects of vitamin E, which builds up in fat stores and sticks around longer, he says.
The National Institute on Aging is now funding randomized, double-blind, placebo-controlled clinical trials on antioxidants and Alzheimer's to probe the question of whether antioxidants can delay or prevent dementia. But these trials don't specifically address a high-dose combination of vitamins E and C.
The researchers report their findings in the January issue of the Archives of Neurology.
In theory, vitamins with antioxidant properties could ward off Alzheimer's by protecting brain cells from the ravages of renegade oxygen molecules that accumulate in the organ with age.
However, studies of vitamin use in groups have turned up conflicting results on whether people who consume more antioxidants are less likely to develop Alzheimer's.
Zandi and his colleagues followed 4,740 residents, age 65 and up, of Cache County, Utah, a mountainous region near the Idaho border. At the beginning of the study, in 1995, 200 people had probable Alzheimer's disease as determined by a battery of neurological tests.
At the start of the project, the researchers queried volunteers about their diet habits, especially their intake of vitamin supplements, including individual nutrients and multivitamins. They repeated their testing and interviews three years later, at which point 3,220 people remained in the study. Among those, 104 were found to have developed Alzheimer's disease since the start of the study.
About four in 10 people (37 percent) reported taking either high-dose vitamins C and E (17 percent) or multivitamins (20 percent). High-dose supplements had to have at least 400 international units (IU) of vitamin E and half a gram of vitamin C, also called ascorbic acid. Those taking the supplements tended to be younger, healthier, and better educated than non-users, and were more likely to be women.
After accounting for age, sex, overall health, and education, the researchers found that people who took high doses of vitamins C and E were less likely to have Alzheimer's at the start of the study and to have developed it three years later. People who took vitamin E supplements and lower doses of vitamin C, in the form of multivitamins, seemed to get some protection against Alzheimer's, but the effect wasn't statistically robust. There was no difference in Alzheimer's risk for people who took only multivitamins or vitamin B-complex vitamins.
Zandi says the protective effect of vitamins E and C against dementia is roughly as great as that seen with regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen. Studies suggest that people who take these medications over time may cut their risk of the disease by 50 percent to 60 percent.
Current guidelines call for people to get at least 22 IUs of vitamin E and 75 to 90 milligrams of vitamin C daily. Both nutrients are considered relatively safe at higher doses, Zandi says, although vitamin E has been linked to bleeding problems in some people who consume more than 1,500 IUs a day.
Zandi admits, however, that the 1,500-odd people who dropped out of the study -- many died -- could skew the findings. And, he says, Utah residents don't exactly make a postcard of America; they're overwhelmingly whites of European extraction who lead remarkably healthful lives.
Still, Zandi adds, his study's dropout rate isn't particularly high compared with other population analyses, and the homogeneity of the volunteers and their longevity makes it easier to control for research variables that can confound results.
Dr. John Morris, a board member of the Alzheimer's Association who is familiar with Zandi's study, says the work "is not conclusive."
It "does not prove that taking the vitamins themselves is the reason they didn't get Alzheimer's as much" as people who didn't take them, says Morris, a neurologist at Washington University in St. Louis.
But, he adds, the link between antioxidants and protection from the disease is plausible. "We know that over a lifetime, nerve cells are susceptible to oxidative stress," he says.
More information
For more on Alzheimer's disease, try the Alzheimer's Association or the National Institutes of Health.
