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FRUITS, VEGETABLES, AND CAROTENES:
ARE THEY PROTECTIVE AGAINST BREAST CANCER?

(February 2002)

Fruits and vegetables taken together (rather than any specific fruit or vegetable) offer moderate protection against some cancers. The evidence on breast cancer has been less strong and is, therefore, controversial. A recent study published in the American Journal of Epidemiology June 15, 2001 looks at blood levels of various carotenes and risk of breast cancer. Many fruits and vegetables contain a variety of carotenes. In this study, 270 breast cancer cases enrolled in the New York University Women’s Health Study, were compared with 270 controls. At enrollment, when cancer free, a total of 14,275 women ages 35 to 65 years had blood taken and stored. When the 270 women subsequently developed breast cancer, their blood and the blood of controls was unfrozen and analyzed for Beta carotene and other carotenes, including alpha carotene, B cryptoxanthin and lutein. Those women who at enrollment had the lowest alpha carotene, beta carotene, or Beta cryptoxanthin blood levels had a twofold increased risk of breast cancer.

Commentary: The conclusion that increasing carotene intake may offer some protection against breast cancer is not supported by most other studies. One of the other studies did find some protection, but not for the same carotenes that were thought to be protective in this study. In a thoughtful commentary, Dr Thomas Rohan of Albert Einstein College of Medicine noted that a recent review indicated that, when all available studies were analyzed together, a high vegetable intake was associated with a 25 percent reduction in breast cancer risk. High fruit intake was associated with a lesser and statistically insignificant reduction in risk (6 percent). Dr Rohan points out that fruits and vegetables contain a lot of substances that could be protective in addition to carotenes, including folic acid, vitamins C and E, and flavonoids. In reply to the commentary, the investigators agree that the protection found may have nothing to do with carotenes; it may be the fruits and vegetables themselves.

Although this study and the review cited support the beneficial effect of fruits and vegetables for breast cancer prevention, another careful, but contradictory, analysis of the effect of fruits and vegetables in the diet on the occurrence of breast cancer appeared in the Journal of the American Medical Association February 14, 2001. The authors analyzed eight studies that together included 7,377 cases of breast cancer among 351,825 women. No reduction in risk was found for fruits or vegetables or the two combined. Even when the investigators looked at women who were in the top 10 percent of fruit and vegetable consumption, there was only a small reduction in risk of breast cancer (3 to 9 percent) that was not statistically significant. The authors concluded "these results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk".

for the ability of high intake of fruits and vegetables to offer modest protection against several types of cancer.

for the ability of vegetables and fruits, particularly vegetables, to offer modest protection against breast cancer.

for the ability of carotenes to protect against breast cancer.

The take-home message is: include plenty of fruits and vegetables in your diet, but do not depend on dietary supplements containing carotenes or other substances, including vitamins, found in fruits and vegetables to protect against any cancer, including breast cancer. With breast cancer, your diet may or may not help. Healthful Life strongly believes the most important single action a woman can take to protect against death from breast cancer is an annual mammogram starting at age 40 (see current editorial about the attack on mammography).

Toniolo, P., et al. Serum carotenoids and breast cancer. American Journal of Epidemiology. Vol 153 (June 15) Pgs 1142-1147. 2001.

Smith-Warner, S.A., et al. Intake of fruits and vegetables and risk of breast cancer. Journal of the American Medical Association. Vol 285 (February 14) Pgs 769-776. 2001.

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