NEW YORK (Reuters Health) – Women who want to protect themselves from developing breast cancer before menopause should be sure to eat their carrots, the results of new research suggest.

Dr. Laura I. Mignone of the Harvard School of Public Health in Boston found that the more servings of carotenoid-rich vegetables premenopausal women ate every day, the lower was their risk of developing the disease.

Carotenoids are plant pigments with powerful antioxidant properties. They are found in “carrots, kales, green leafy vegetables, the things that your mom always told you to eat,” Mignone said in an interview with Reuters Health.

Most breast cancer risk factors are hormone dependent, for example, the age at which a woman begins menstruating or how old she was when she had her first child, Mignone noted. “These are things that women aren’t able to change.”

But, she added, diet could be a modifiable risk factor. She and her colleagues examined the relationship between levels of carotenoid-rich fruits and vegetables in the diet and breast cancer risk by comparing the diets of 5,707 women with invasive breast cancer and 6,389 healthy controls.

Higher levels of the carotenoids vitamin A, beta carotene, alpha carotene, and lutein/zeaxanthin reduced breast cancer risk among premenopausal women, but not postmenopausal women. Eating at least two servings of carotenoid-rich vegetables each day reduced the risk by 17 percent, Mignone explained.

Carotenoids have been shown to interfere with estrogen signaling, the researcher noted, which she and her colleagues believe might explain why their cancer-preventing effects would be limited to premenopausal women.

And, she added, the pigments’ antioxidant effects are also likely a factor. “They are very strong antioxidants in the body, and they can be absorbing a lot of the carcinogens that people are exposed to.”

SOURCE: International Journal of Cancer, June 15, 2009.