The low-cost supplements could be a valuable therapy in developing countries, especially for pregnant women and new mothers, who tend to be more vulnerable, say the scientists.
At the end of 2003, approximately 40 million people worldwide were infected with HIV, according to the UN, but fewer than 8 per cent of the 6 million patients with advanced disease eligible for antiretroviral treatment were receiving it.
Supplements therefore, shown in the new study to slow progression of HIV by 30 per cent, could delay the need for antiretroviral therapy, saving the drugs for when they may be most needed and reducing drug-related adverse events and costs, write the researchers in today's issue of The New England Journal of Medicine (volume 351:23-32).
In the study, 1078 pregnant women infected with HIV were enrolled by Muhimbili university in Dar es Salaam, Tanzania. They received either vitamin A (5000 IU of preformed vitamin A and 30mg beta-carotene), multivitamins (vitamins B, 500mg C, and 30mg E), both vitamin A and the multivitamins in the same doses, or a placebo everyday for on average six years.
Of the 271 women who received multivitamins, 67 had progression to full AIDS (World Health Organisation stage 4 of the disease) or died, compared with 83 of 267 women who received placebo. This means a risk reduction of almost 30 per cent.
The counts of CD-4 cells, the immune system cells that the virus attacks, also remained higher in the multivitamins group and these women also had fewer incidents of thrush, throat ulcers, inflamed gums, nausea, rashes, fatigue and other debilitating side effects.
These effects are thought to be a result of vitamins C and E and the B group's role in enhancing cellular immunity. Multivitamins may also reduce HIV replication, demonstrated by a much reduced viral load in the study. The researchers propose that as HIV replication in vitro is increased by oxidative stress, the antioxidant vitamins C and E may be responsible for this change.
The effects of receiving vitamin A alone were smaller however and for the most part not significantly different from those produced by placebo. In addition, about a quarter of the women who received the multivitamins still died or reached full AIDS during the study, showing that the supplements cannot cure the disease or replace antiretroviral treatment.
The findings however support previous studies on men in the US. Those with lower serum vitamin E levels or vitamin B12 were more likely than those with higher levels to have progression to AIDS.
But while researchers have previously noticed that vitamin-deficient patients sickened faster than well-fed ones, it has been difficult to separate poor nutrition from other health problems, like drug and alcohol abuse.