The role of breastfeeding in the transmission of HIV from mother to infant has been exaggerated, according to the latest evidence.

In fact, infant health may be compromised by trying to get HIV positive mothers to use formula milk.

A recent review by researchers at Cornell University in New York set out to separate myth from reality about HIV and breastfeeding by studying African women. Of the estimated 590,000 infants born with acquired HIV-1 in 1998, 90 per cent lived in Africa.

The conventional advice is that HIV positive mothers should feed their babies formula to prevent transmission of the virus. However, the Cornell Researchers' data show that, even in those areas with the highest prevalence of HIV, only about 4 per cent of infants will contract the disease through breastmilk. In areas where prevalence is low, only 1 per cent of infants will become infected.

The risks of formula feeding in developing countries are the same as those in the West only more so. Bottlefed babies suffer from five or six times more infections than breastfed ones.

In the developing world, diarrhoea, acute respiratory infections and other infections can be deadly, and mortality among formula fed babies is high.

The policy of no breastfeeding for HIV positive mothers was put in place in 1998 on the basis of very little evidence. However, review of the evidence suggests that, compared with mixed feeding, exclusively breastfeeding provides significantly better protection from HIV transmission. Breastfed babies will have healthier guts which act as viral barriers, and breastmilk is known to contain immune factors shown in vitro to have antiviral and anti HIV effects (BMJ, 2000; 320: 1656-60).