A study in the British medical journal, Lancet, shows that eating a lot of fat, particularly saturated fat in meat, increases a woman's risk for breast cancer. Women who take in more than 90 grams of fat a day have twice the risk of those who eat less than 40 grams. However, this study's conclusion is the opposite of two recent larger studies that found no association between dietary fat and breast cancer. This study included 13,000 women, and the authors claim that the other studies used a food frequency questionnaire, which is less dependable than the food diaries used in this study.

The chance of a woman developing breast cancer sometime during her life is between 8 percent and 11 percent, according to the World Health Organization. Experiments in lab animals indicate that high fat intake could increase the likelihood of breast cancer. However, most of the recent studies, which followed groups of healthy women over time, have failed to find a link. The probable explanation for the association between a high saturated fat diet and breast cancer is that estrogen is secreted from a woman's blood stream into the intestines and a high-fat diet increases reabsorption of estrogen back into the bloodstream to stimulate the breast to grow and increase risk for breast cancer.

The following factors have all been associated with increased risk for breast cancer and we do not know how much weight to put on any of them. The strongest risk factor for breast cancer is increased exposure to estrogen. Starting to menstruate at a young age, and stopping menstruation to go into the menopause at a late age, both increase risk. Taking estrogen and progesterone also increase risk for breast cancer. Lack of vitamin D is associated with increased risk for breast cancer. So is being fat, particularly storing fat primarily in the belly, rather than the hips. Soybeans have been shown both to prevent and to cause breast cancer. Diabetes increases risk for breast cancer. Smoking, lack of exercise, trans fats, and alcohol all increase risk.

What you should draw from all this research is that we don't know what causes breast cancer, but to be safe, eat lots for vegetables, reduce your intake of fat, saturated fat and partially hydrogenated oils (trans fats). Get plenty of exercise, and don't be overweight, and certainly do not smoke. If you are diabetic, avoid sugar and flour and keep your HBA1C under 6.1. Even if none of these recommendations prevent breath cancer, they are all healthful habits that will help protect your health other

Lancet, July 21, 2003

Get our newsletter