The research highlights the need of further research into the role of micronutrients in AIDS management, but it should be stressed that the carotenoids are not a replacement for standard antiretroviral drugs, but a potential supplement .
"Today, when antiretroviral therapy (ART) is expected to be successful in most cases, natural mixed carotenoid supplementation may be a potential low-cost intervention for those with inadequate response to conventional treatment or lacking access to ART," wrote the researchers, led by Professor D. William Cameron, in the European Journal of Clinical Nutrition (Vol. 60, pp. 1266-1276).
A report published by the World Health Organisation in November 2005 showed that the number of people living with HIV was at its highest ever - 40.3 million. More than 3 million people died of AIDS-related illnesses in 2005, with more than 500,000 of these children.
"In observational studies, low micronutrient concentrations, including vitamin A and carotenoids, are associated with HIV disease progression, mortality and vertical viral transmission, and higher intake with delayed disease progression and survival," wrote lead author James Austin from the Community Research Initiative of Toronto.
The new placebo-controlled, prospective, randomised, double-blind, multi-centre clinical trial looked at the effects of a high dose mixed carotenoid supplement (equivalent to 72 mg beta-carotene) or placebo on new or recurrent AIDS-defining event or death. The secondary outcome was the effect of the supplements on overall mortality.
Both groups received a daily multivitamin, including vitamin A and trace elements.
The researchers recruited 331 people who were HIV-seropositive, at least 18 years old and at risk of HIV immune disease progression. The average CD4 T-lymphocyte count (the immune system cells that the virus attacks) at baseline was 68 cells per microlitre of serum, while average baseline serum carotene levels were 2.21 micromoles per litre.
After an average of 13 months of follow-up the researchers report that 36 of the participants had died. In participants who had received the carotenoid supplements, serum carotene levels had doubled during the trial, despite problems with the supplement supply that showed the formulated dose dropped from 64 mg at the start to 9.2 mg at the end of the study. Due to these supply problems the study was stopped prematurely.
"Despite lack of uniformity in the dose… and the early termination of the trial, we observed a significant elevation in serum carotene to 18 months follow-up," wrote Austin.
The CD4 T-lymphocyte count was also found to increase as a result of carotenoid supplementation, said the researchers. No change in CD4 T-lymphocyte levels was observed for the placebo group.
While no significant effect on new or recurrent AIDS-defining event or death was observed, the secondary outcome of overall mortality was found to decrease in the carotenoid-supplemented group.
"Supplementation with micronutrients and natural mixed carotenoids may improve survival by correction of a micronutrient deficiency," said the researchers.
The mechanism behind the apparent benefits is not known, they said, but could be through an interaction with the antiretroviral drugs, which could boost serum concentrations and/or improve the response.
The result of this study, said the researchers, "underscores the importance of further research into the role of micronutrients in AIDS management."
The Canadian researchers called for larger studies to corroborate the results of this study, while stressing that the carotene supplements should be closely monitored for quality and standards.
Commenting independently on the research, Bonita de Boer, information officer for AVERT, an international HIV and AIDS charity based in the UK, told NutraIngredients.com: "This research is very interesting and provides further support to previous studies demonstrating the benefits of Vitamin A and micronutrient supplementation. It is important to note that the study does not suggest carotenoids should replace antiretroviral drugs, but with further study there may well be a case for introducing them as a supplement alongside standard AIDS treatment."