Is Breast Cancer on Your Menu?

Q: I've heard that eating grapefruit increases the risk for breast cancer. I drink a lot of grapefruit juce and wondered whether I should be worried. Can certain foods really cause cancer?

A: There are no evidenced-based scientific studies that link grapefruit juice to breast cancer. However, a study discussed in the July 2007 issue of the British Journal of Cancer suggested post-menopausal women consuming at least one-quarter grapefruit per day (the study did not examine those drinking grapefruit juice) or pomelo (similar to grapefruit but larger) had a 30 percent higher risk for breast cancer compared to women who didn't eat grapefruit. Here's the caveat: No warnings from the Food and Drug Administration have been issued in regard to grapefruit and breast cancer. The findings of the study were preliminary and more research is needed to back up or challenge those results.

Examine medical study news carefully

News discussing medical studies have the potential to bring hope or trigger worry. Thus, it's important to examine the facts of any study, evaluate other research to see if the findings are supported, and talk to your doctor about how the information may potentially affect your health. That said, the July 2007 study was interesting and conducted well, so let's take a closer look at what's behind the results.

• The researchers reviewed data from a lifestyle study of over 46,000 post-menopausal women from a variety of ethnic backgrounds, including some who either did or did not use estrogen replacement hormone therapy. This means the study represented a diverse group of women instead of one particular segment of the population.
• The study did not include pre-menopausal women or those with a personal history of breast cancer. This means it is not known which, if any, of this information would relate to those particular groups of women.
• Several previous studies demonstrated higher estrogen levels in women who regularly ate grapefruit or drank grapefruit juice. Unfortunately, this particular study did not measure the baseline estrogen levels of the participants before they ate the grapefruit, so we don't know the impact, if any, the fruit had on their hormone levels.
• It is well known that grapefruit (or its juice) may cause increased blood levels of certain drugs (some antibiotics, cholesterol lowering medication, and others), including estrogen-containing hormone replacement therapies (acknowledged by the investigators).

What does it all mean?

Elevated estrogen levels are important because excess estrogen does seem to stimulate the majority of breast cancers. However, don't toss the grapefruit yet, because there are other potential contributing factors that increase the body's blood levels of estrogen. These include but aren't limited to: obesity, alcoholism, adrenal and pituitary gland tumors and liver disease, as well as environmental exposures to certain chemicals and pesticides. There is also discussion regarding the potential for processed meats (preservatives, certain food colorings, etc.) and hormonally enhanced food products to increase estrogen levels or impact health.

When a study is released on one particular food, food group, chemical or ingredient, there are many factors to consider before a definitive conclusion can be reached about the dangers of that food. In the meantime, if you are concerned, it's reasonable to cut back on grapefruit and add some other citrus fruits to the mix.