Modestly high consumption of vitamins may help people infected with the AIDS virus to extend the time before they develop the full-blown disease, according to a study by Johns Hopkins scientists.
If the findings are confirmed by other studies, vitamins could prove a cheap, palatable and readily available therapy for infected people eager to stave off the first symptoms of acquired immune deficiency syndrome.
In a study of 281 infected gay men from Baltimore, those who consumed vitamins A, B1, niacin and possibly C at levels above the government's "daily recommended allowance" were about 40 percent less likely to progress to AIDS over 7 years.
Put another way, vitamins appeared to give the men about two additional years before they developed AIDS.
Scientists at the Johns Hopkins School of Hygiene and Public Health were quick to caution against taking large doses of vitamins, which in some cases can be toxic. Instead, they said the benefits were linked to levels that can be gained from a healthy, well-balanced diet and standard doses of multivitamins.
"If taken in reasonable doses and you don't get carried away with megadoses, it's plausible you could do some good based on this data," said Dr. Neil Graham, senior author of the study, which appears in the December issue of the American Journal of Epidemiology.
Doctors and activists long have recommended a nutritious diet for infected individuals, but the Hopkins study presents the first evidence linking nutrient intake to the progression to AIDS.
Dr. Graham said the study is not conclusive, in part because it was not a controlled trial in which one group given a uniform dosage is compared to another given a placebo. Such studies often are considered the "gold standard" in medical research.
In this study, volunteers recruited in 1984 were asked to fill out detailed questionnaires in which they recorded how frequently they consumed any of 116 food items and which nutritional supplements they were taking. The scientists then correlated the intake of various vitamins with the time it took for each man to develop AIDS.
Dr. Graham said vitamins might give added benefits to people who already are taking AZT or DDI, prescription drugs taken to slow the progression of HIV infection. Vitamins also might provide an alternative to people who cannot tolerate the side effects of those drugs, he said.
A year's supply of multivitamins probably costs less than $50, he said. In contrast, a year's supply of AZT can cost $3,000.
People who took more than 20,000 international units of Vitamin A each day did not improve the course of their infection. (The recommended daily allowance is 3,000 units.) But people who consumed between 9,000 and 20,000 units reduced their chances of progressing to AIDS over the seven-year period by 45 percent compared to people who took normal doses.
"I'd been aware that vitamin A is protective against mortality in some infectious diseases, like diarrhea," Dr. Graham said, adding that it wouldn't surprise him if the vitamin temporarily protects the immune systems of people who are infected with the AIDS virus.
Scientists remain stymied in their search for a drug to cure AIDS.
Alice Tang, a doctoral student who was the study's lead author, said people should look first to foods for their vitamins. Then, for people who want supplements, a daily multivitamin should be enough.
"The people were getting vitamins from both sources," she said. "It's probably better to just eat a well-balanced diet."