Friday, August 27, 2010
Vitamin A and beta-carotene supplements are unsafe for HIV-positive
women who breastfeed because they may boost the excretion of HIV in
breast milk---thereby increasing the chances of transmitting the
infection to the child, a pair of new studies suggest.
Epidemiologist Eduardo Villamor of the University of Michigan
School of Public Health says transmission of HIV through
breastfeeding happens because breast milk carries viral particles
that the baby ingests. Supplementing HIV-positive women with
vitamin A and beta-carotene appears to increase the amount of the
virus in milk.
This may be partly because the same nutrients raise the risk of
developing subclinical mastitis, an inflammatory condition which
causes blood plasma to leak into the mammary gland and viral
particles to then leak into the milk, he says.
Villamor's findings appear in two separate articles in the American
Journal of Clinical Nutrition and the Journal of Nutrition. The
results are significant because they provide biological
explanations for a previous report that supplementation with these
nutrients increased chances of mother-to-child HIV
transmission.
"So there are now strong arguments to consider the implications of
supplementation to pregnant or lactating women who are
HIV-positive," said Villamor, associate professor of epidemiology
and environmental health sciences. "It does not look like it's a
safe intervention for them."
Mother-to-child HIV transmission is a huge problem in developing
countries where HIV is prevalent, Villamor said. In 2008 alone,
there were 430,000 new infections and more than 95 percent of those
resulted from mother-to-child transmission. Most were in
sub-Saharan Africa.
In one of the studies, 1,078 HIV-infected women were divided into
four groups. The test groups received either 5,000 IU of vitamin A
and 30 mg of beta-carotene everyday during gestation and the
lactation period, or a control regimen. The dose for beta-carotene
was higher than the amount usually provided by the diet, according
to Villamor. Smaller doses might not have the same effect.
Villamor said tests trying to separate the effects of each nutrient
showed that beta-carotene seemed to increase the amount of HIV in
breast milk independent of vitamin A, but an effect of vitamin A
alone cannot be ruled out. The findings are potentially
controversial because vitamin A is an important supplement for
postpartum women in countries where HIV infection is highly
prevalent, but supplementation programs may not take into account a
woman's HIV status.
"The takeaway is that daily supplementation of HIV-infected
pregnant or lactating women with vitamin A and beta-carotene at the
doses tested is probably not safe and efforts need to be
strengthened on preventing mother-to-child transmission through
other interventions such as anti-retroviral regimens," Villamor
said.
###
Thanks to University of Michigan for this
article.