Prostate Cancer? Add Tomatoes and Broccoli to Your Diet

Posted on Thursday, March 22, 2007
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Animal study shows prevention and treatment benefits by Jeni Baker, Cancer Monthly Staff Writer

Most of us have heard about the health benefits of eating tomatoes and broccoli. What you probably haven’t heard is that a recent animal study yielded some interesting data about how these vegetables, when eaten together, can be a valuable two-pronged weapon against prostate cancer.

“The diet targeted the tumors, the drug didn’t”

A study* conducted by nutritional scientists from the University of Illinois, Urbana, and oncologists from the James Cancer Hospital and Solove Research Institute shows that the active ingredients in broccoli and tomatoes work together to inhibit its growth.

One month before being injected with prostate cancer cells, 206 male rats began a 22-week diet that included tomatoes and broccoli. Because the cancer cells were injected into the rats’ backs, researchers were able to measure the cancer tumors throughout the study without affecting the animals’ healthy prostate glands.

These rats were compared to two control groups – one made up of rats that were castrated (to remove the hormones required for prostate cancer growth) and one comprised of rats that were given finasteride, a compound sold for the treatment of enlarged prostrates. At the end of study, the tumors were removed from the rats, weighed, and compared to the normal prostates.

Perhaps the most noteworthy finding is that the diet thwarted tumor development more effectively than the drug did, says co-author Kirstie Canene-Adams, a University of Illinois doctoral candidate.

“The finasteride did not hinder tumor growth, but the diet did,” she says. “This is very exciting because it says that something in the cancer was altered due to the diet. The diet targeted the tumors, but the drug didn’t.”

Also interesting is that, when fed together, broccoli and tomatoes reduced tumor growth better than when each food was fed by itself.

Simply put, the diet worked in two ways says Canene-Adams: by preventing cancer cells from growing, and by causing more of the cancer cells to die.

What we humans can do

Since human males are a good bit larger than their rat counterparts, how do the food amounts translate – and are there any concerns about toxicity?

Based on metabolic rate, men would have to eat the following each day to match what the rats ate: two-and-a-half cups of raw tomatoes, one cup of tomato sauce, OR a half-cup of tomato paste, plus 1.4 cups of raw or gently cooked broccoli.

That’s a lot of tomatoes and broccoli. Fortunately, human studies show that eating these foods just a few times a week reduces prostate cancer risk, says Canene-Adams. As for toxicity, “these are foods that Americans normally eat, and there’s no known toxicity associated with them,” she says.

Prostate cancer patients – as well as men at risk for the disease – should speak with their doctors if they are interested in adding the tomato-broccoli combo to their diets. And all men should get regular PSA tests, says Canene-Adams – starting at around age 40 for men with a family history of prostate cancer, and at about age 50 for those with no known risk factors.

If you’re a prostate cancer patient, there’s one more benefit to eating your vegetables.

“When people have cancer, they want to have a feeling of control, and what they put into their bodies is something they can control,” Canene-Adams says. “Being able to improve their diets to include more vegetables empowers patients, and that’s important psychologically.”

And, she says, whether they have cancer or not, it’s always a good thing when people understand the role nutrition plays in the prevention and treatment of the disease.

* Canene-Adams et al., Combinations of Tomato and Broccoli Enhance Anti-Tumor Activity in Dunning R3327-H Prostate Adenocarcinomas. Cancer Res. 2007 Jan 15;67(2):836-43.Epub 2007 Jan 9.