TORONTO, Oct 21: New findings about the relationship between breast feeding and the ailments of allergies and asthma have thrown the proverbial cat among the pigeons of received wisdom.

Scientists in two countries, Canada and New Zealand, have come across strong evidence that breast-feeding not only does not protect against allergic diseases as is widely believed but might even increase the risk.

A team headed by Professor Malcolm Sears from McMaster University, Ontario, studied the long-term effects of breast-feeding in 1,000 children from Dunedin, New Zealand, born between 1972 and 1973.

The children were checked for lung function and asthma symptoms every two to five years up to the age of 26. Skin-prick tests for allergies were carried out at ages 13 and 21.

Half the children in the survey had been breast-fed. More of them became allergic to cats, house-dust mite and grass pollen than those who had not been breast-fed by their mothers.

A greater number of breast-fed children were discovered to be asthmatic between the ages of nine and 26.

The pattern remained clear when factors such as socioeconomic status, parental smoking and use of sheepskin bedding in infancy were taken into account. Children breast-fed for more than four weeks were about twice as likely to have an allergy or asthma in later life than children who were not breast-fed.

Professor Sears said: “Breast-feeding could be promoted for many reasons, including optimum nutrition and reduction of risk of infant infections. However, the role of breast-feeding in protection of children against atopy (allergy) and asthma cannot be supported on the basis of the present balance of evidence.”

The researchers publishing their findings in the Lancet medical journal, saying their original hypothesis had been that breast- feeding would protect against asthma and allergy.

Instead they concluded that breast-feeding does not protect children against atopy and asthma, and may even increase the risk.

Why breast-feeding, normally accepted as healthy, should increase allergy and asthma risk is a mystery. The explanation might be that breast-feeding affects the balance of intestinal bacteria, said the authors.—dpa