Zinc supplements could cut the death rate among low birth weight babies by a third, researchers have claimed.

The zinc may boost the babies' immune systems, helping them fight off disease.

Dr Robert Black and Sunil Sazawal from Johns Hopkins University in Maryland and colleagues at Annamalai University in India did tests on 1,250 low birth weight Indian children.

The children were either given zinc supplements, zinc with other vitamins and minerals, vitamins and minerals without zinc, vitamins alone or a dummy pill.

The babies who got zinc, either alone or with other nutrients, were one third less likely to die.

In a second analysis, a Johns Hopkins team pooled the results from 17 international zinc studies and found that adding zinc to the diet can reduce incidents of diarrhoea by up to 25% and pneumonia by 41%.

Poor diet to blame

Red meat is a good source of zinc

Approximately 60% of babies born in developing countries suffer from low birth weight.

This is usually due to the poor diet of the mother, although it can also be caused by infection.

Dr Black said: "There is evidence that zinc plays a role in the development of the immune system of the foetus, therefore it is quite possible that children whose mothers have a diet deficient in zinc will be born with less well-developed immune systems.

"Giving additional zinc after birth might help to correct that deficiency in the immune system."

Dr Black said the babies in the study were given five milligrams of zinc a day - the recommended daily dose for children aged one to nine months.

Red meat and other animal flesh is the best source of dietary zinc. It is also found in some nuts and gains.