WESTERN diets could increase the risk of breast cancer, according to new research from Durham University.

Experts believe that diets rich in fatty food boost levels of the female hormone oestrogen, thought to be a major cause of the disease.

Although the hormone can help reduce the risk of heart disease, it also causes cell division in the breast, and repeated cell division makes cancer more likely.

Dr Tessa Pollard, a biological anthropology lecturer at Durham University, said: "There is very good reason to believe that those women who produce higher levels of oestrogen over their lifespan are more likely to develop breast cancer.

"Several studies have shown that the less food you eat and the more physically active you are, the less oestrogen your ovaries produce."

This could explain why industrialised countries have higher breast cancer rates than those than poorer countries, where the diet is more meagre.

Dr Pollard outlined her theories at the British Association Festival of Science, at Salford University.

Her work focuses on testing whether a women's early environment, in the womb and in early childhood, helps set her oestrogen levels for life.

She has found that women in western society give birth to babies with high levels of oestrogen but women in poorer African nations gave birth to babies with normal levels.

She said: "We can begin to pinpoint which women will be at greater risk of breast cancer and heart disease because of their oestrogen levels."

The number of breast cancer cases in Britain is at an all- time high. There are currently more than 40,000 cases each year and 13,000 deaths.