Fiber May Decrease Breast Cancer Risk

Researchers from the University of Leeds's Center for Epidemiology and Biostatistics have been monitoring the eating habits and health of more than 35,000 women for the past seven years, and their latest results were published in the December 2006 issue of the International Journal of Epidemiology. Their findings suggest that among the pre-menopausal women group, those who have the greatest intake of fiber have slashed their risk of breast cancer by 50%.

The study was led by Professor Janet Cade, who explained, "Previous research hasn't shown a convincing link between increased dietary fiber and a lower risk of breast cancer. But earlier studies didn't draw any distinction between pre- and post-menopausal women. Our study found no protective effect in the older group, but significant evidence of a link in the pre-menopausal women.”

Of the large group, 257 pre-menopausal women have developed breast cancer during the study. These were shown to be women who had a greater percentage of energy derived from protein, and lower intakes of dietary fiber and vitamin C, compared to the cancer-free women.

The study, which received initial funding from the World Cancer Research Fund, suggests several possible reasons for this effect: (1) High-fiber foods are rich in vitamins, zinc, and other micro-nutrients that have protective anti-oxidant characteristics; (2) Fiber can level out the highs and lows in insulin levels in the body. High levels of insulin may be one possible cause of cancer; and (3) there is a known link between breast cancer and the female hormone estrogen, and dietary fiber has been demonstrated to regulate estrogen levels in the body. This effect would be especially relevant to the pre-menopausal group, which naturally has far higher levels of the hormone.

Professor Cade remarked, "Also, we don't yet know at which point in life dietary habits impact on a woman's susceptibility to breast cancer. The relevant exposure may be earlier in life, explaining why the protective effect was not shown in the post-menopausal group.”

Whatever the exact mechanism, or combination of mechanisms, the study does demonstrate a statistically significant effect and supports the message of eating well to stay healthy. Professor Cade added, "It goes along with the general healthy eating advice to make sure that you are getting plenty of fiber in your diet through breakfast cereals, bread, pasta, fruit, and vegetables.”


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