Fatty diet helps cause breast cancer by killing nutrient, study shows

People who eat a lot of fat run a higher risk of breast cancer, a study shows. The best explanation for the disease, which claims 13,000 lives a year in Britain, is that a fatty Western diet depletes the breast tissue of an essential nutrient that protects against the disease.

People who eat a lot of fat run a higher risk of breast cancer, a study shows. The best explanation for the disease, which claims 13,000 lives a year in Britain, is that a fatty Western diet depletes the breast tissue of an essential nutrient that protects against the disease.

The unidentified nutrient is likely to be a trace element present in the soil, in varying amounts in different areas, taken up by plants and entering the food chain. It is probably present at high levels in cereals and pulses, but at only low levels, or not at all, in fat, red meat and dairy products.

Fat has long been cited as a cause of breast cancer since scientists noted that countries with low fat diets, such as Japan, had a low incidence of the disease. But the varying incidence of the disease within populations eating broadly the same diet has never been explained.

A review of research on causes of breast cancer, by Dr Richard Wiseman, of the London School of Hygiene and Tropical Medicine, concludes that a diet high in fat is not likely to be a direct cause of the disease. But the indirect effect of such a diet depletes the breast of a protective factor.

The main cause of breast cancer remains unknown. The American Public Health Association lists obesity, age over 30 at birth of first child, childlessness and radiation as the chief predisposing factors, but together they account for only 26 per cent of the risk.

Dr Wiseman, in the Journal of Epidemiology and Community Health, says there is likely to be "a single causal agent for the majority of cases and it is a deficiency of this agent that is responsible".

Genes are not the answer, because there is a low prevalence of family history and women with similar genetic profiles develop the disease at different rates when they move to other countries. Pollution or infection have also been ruled out as causes.