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FRUITS, VEGETABLES, CAROTENES, AND BREAST CANCER.
ARE THEY PROTECTIVE?

(July 2003)

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 looks at blood levels of various carotenes and risk of breast cancer. Many fruits and vegetables contain carotenes. In this study, 270 breast cancer cases 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 bloods and the blood of controls were 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 statistically significant twofold increased risk of breast cancer.

The authors conclude: "These observations offer evidence that a low intake of carotenoids through poor diet and/or lack of vitamin supplementation may be associated with increased risk of breast cancer. Our results seem to add substance to the theory that abundant consumption of vegetables and fruit is protective against breast cancer in women."

Commentary: One major problem with this study is that the conclusions are based on a single blood specimen on each participant. The conclusion that increasing carotene intake may offer some protection against breast cancer is not supported by most other studies. One of the other recent studies did find some protection, but not for the same carotenes. In a thoughtful commentary, Dr Thomas Rohan of the Albert Einstein College of Medicine, Bronx, NY, points out the inconsistencies in the literature and concludes that a protective effect of carotenoids has not been shown conclusively for breast cancer; he further notes that fruits and vegetables, which do seem to offer some protection against breast cancer, contain a lot of substances that could be protective aside from carotenes. Interestingly, a recent review indicates that, when all available studies are analyzed together, a high vegetable intake is associated with a 25 percent reduction in breast cancer risk. High fruit intake was associated with a lesser reduction in risk (6 percent).

Ratings:

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

for the ability of carotenes to protect against breast cancer.

The take home message is that some protection against some cancers can be achieved by including plenty of fruits and vegetables in your diet. Vegetables are particularly important, including the cruciferous vegetables, such as broccoli, brussel sprouts, cabbage, cauliflower. But, you cannot depend on dietary supplements that contain substances found in fruits and vegetables to protect against any cancer, including breast cancer. The one known exception is folic acid which may well offer some protection against some cancers. Everyone ought to get at least 400 micrograms (preferably 800 micrograms) a day from the diet, from folate-fortified foods (such as cereals), or from a dietary supplement (CLICK HERE for a list of foods high in folates). For folate content of cereals and grains, be sure to read the labels).

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

Gandini, S., et al. Meta-analysis of studies on breast cancer risk and diet: The role of fruit and vegetable consumption. European Journal of Cancer. Vol 36. Pgs 636-646. 2000.

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