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Monday, 30 October, 2000, 00:06 GMT
Fatty diets 'not linked to breast cancer'
Breast scan
High fat diet "does not increase breast cancer risk"
Scientists have produced evidence to debunk the widely held belief that a high fat diet increases the risk of breast cancer in older women.

The theory is that a high fat diet increases production of the female sex hormone oestrogen - high levels of which are linked to an increased risk of breast cancer.

A team from Harvard Medical School carried out the largest and most detailed study ever to test the theory.

This is good news for women

Dr Michelle Holmes, Harvard Medical School

They found no evidence that a high fat diet was linked to oestrogen production. In fact, they found just the opposite.

The researchers, who studied 381 postmenopausal women, found that women who ate less fat than typical actually had higher levels of oestrogen in their blood.

Lead researcher Dr Michelle Holmes said: "This is good news for women. It's one less thing they need to worry about if they are concerned about breast cancer.

"We found no evidence that higher fat intake is associated with higher levels of any reproductive hormones in this group of postmenopausal women."

Diet changes

Dr Holmes said that lowering fat intake to try to reduce hormone levels was probably a waste of time.

Research has established beyond doubt that obese women have a moderately higher risk for developing breast cancer

Dr Tim Key, Imperial Cancer Research Fund

"It does not seem likely that eating a low-fat diet in mid-life can lower hormone production."

The research team took blood samples from the study participants to measure the amount of hormones present in their blood.

Those hormones included oestradiol, which produces oestrogen, and the male sex hormone testosterone.

Researchers also estimated the different kinds of fat the women ate, based on a food survey participants answered twice during the four-year study.

None of the women were using hormone replacement therapy.

The researchers found that as women increased the amount of fat in their diets, the levels of six hormones - including oestradiol and testosterone - went down.


Dr Tim Key, an expert on diet and cancer at the Imperial Cancer Research Fund, said: "There is already substantial evidence indicating that variations in fat intake within typical "Western" diets do not directly alter either blood oestrogen levels or breast cancer risk.

"However, I am uneasy with the researchers' suggestion that women who eat a diet higher in fat may actually have lower hormone levels and therefore, by implication, be at lower risk.

"Such a conclusion would conflict with the results of many other studies, and this finding of the study may be due to chance.

"It is important to remember that, although there is no evidence to directly link a high fat diet with increased risk of breast cancer, research has established beyond doubt that obese women have higher blood oestrogen levels than non-obese women and have a moderately higher risk for developing breast cancer."

The research is published in the Journal of Clinical Oncology.

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