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updated 10/27/2006 10:35:18 AM ET 2006-10-27T14:35:18

Researchers now agree breast cancer occurs in several distinct forms. Although researchers continue to unravel how each form develops, a variety of hormones are critical pieces of the puzzle. While we wait for studies to clarify the best strategies to lower risk, we can identify a few steps likely to promote healthy levels of the hormones involved.

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It’s not only the “female” hormones estrogen and progesterone that influence breast cancer risk. According to several comprehensive studies, high levels of the “male” hormone testosterone raise risk of both premenopausal and postmenopausal breast cancer. Higher levels of sex hormone binding globulin (SHBG), which regulates the action and availability of these hormones, seem to protect against development of breast cancer, at least in women past menopause.

High levels of the hormone insulin and insulin-related growth factors consistently increase breast cancer risk after menopause. Some scientists theorize insulin and insulin-related growth factors may stimulate the growth of breast cancer cells; others suggest insulin may raise testosterone or decrease SHBG levels.

Regular exercise is one way to alter these hormones. Research consistently links physical activity with lower levels of insulin-related growth factors and testosterone.

Weight control is another powerful step to keep these hormones at healthy levels. If you’ve been gaining weight, cutting even 100 calories a day from your eating habits and adding a 15- to 20-minute walk may be enough to stop weight gain. You may need to increase the time you are physically active to 45 to 60 minutes a day.

Aside from help with weight control, total vegetable consumption may not significantly protect against breast cancer. However, eating cruciferous vegetables such as broccoli and cauliflower several times a week may offer protection. The compounds in these vegetables stimulate the production of enzymes that help protect against cancer-causing substances.

Watch portion sizes
Alcohol is one source of calories worth limiting. Studies have shown alcohol can increase a women’s risk of breast cancer, depending upon many factors including genetics and overall diet. But the recommendation for women to limit daily alcohol to no more than one standard drink (5 ounces of wine, 12 ounces of beer, 1.5 ounces of distilled liquor) is a smart move.

Vitamin D is classified as a hormone because the active form is produced within our bodies —we also take this form in from food and supplements. Low blood levels of vitamin D are linked with greater breast density, a characteristic repeatedly associated with greater risk of breast cancer. We don’t know whether vitamin D and calcium, which seem to work together, can change breast density and protect against different forms of breast cancer.

The best way to control weight and promote healthy hormone levels involves paying attention to both what and how much you eat. Check portion sizes, since too much of even healthful food means extra calories. Even if you don’t reach your target weight, limiting calorie intake seems to help control levels of growth factors.

A mostly plant-based diet makes sense for weight control and lower breast cancer risk. Choosing vegetables, fruits, whole grains and beans while limiting sweets, sugar-loaded drinks, saturated fat and refined grains, helps you feel comfortably full on fewer calories, reduces levels of insulin and growth factors, and raises levels of protective SHBG.

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