Broccoli May Cut Prostate Cancer Risk

Tag : prostate cancer

(WebMD)Men who eat broccoli just a few times a week may have a lowerprostate cancer risk than men who don't, new research suggests.

Animal studies have long suggested that broccoli and othercruciferous vegetables help protect against prostate cancer. Thenew research suggests the same thing in humans, albeit indirectly.

Researchers measured changes in gene expression in human prostatetissue associated with eating a broccoli-rich diet.

Compared to men who ate peas four times a week, those who ate fourweekly servings of broccoli for a year showed more changes in geneexpression suggestive of increased protection against prostatecancer.

The findings appear in the July 2 online issue of the journal PLoS ONE.

"It is important to stress that we did not directly measure cancerincidence," Richard F. Mithen, PhD, of the Institute of FoodResearch in Norwich, England, tells WebMD. "But the gene changes wesaw were consistent with a reduction in prostate cancer risk."

Diet Changes Genes

The study is not the first to suggest that changes in diet canchange your genes.

Earlier this month, nutrition researcher Dean Ornish, MD, andcolleagues from the University of California, San Franciscoreported that men with low-risk prostate cancer showed profoundchanges in gene expression when they ate a low-fat diet that washigh in fruits and vegetables .

They found that more than 500 genes were affected, with genesassociated with beneficial effects becoming more active and geneswith cancer-promoting properties becoming less active.

The study included 13 men who ate four 3.5 ounce-servings ofbroccoli a week for a year and eight men who ate the same amount ofpeas.

Prostate tissue samples were collected before the start of thetrial and then after six and 12 months on the broccoli- orpea-intervention diets.

As with the California study, men who regularly ate broccoli showedmore changes in gene expression suggestive of a reduced risk ofcancer.

"These were extensive changes," Mithen says. "Basically, hundredsof genes changed expression. We were quite surprised by thisfinding."

Why Not Peas?

Broccoli and other cruciferous vegetables have compounds known asglucosinolates. Peas do not.

Glucosinolates convert to other compounds known as isothiocyanates,which are widely believed to have tumor-suppressing activities.

Studies suggest that about half the population carries a genecalled GSTM1, which may make these compounds even more protective.

Study participants who expressed the gene showed the mostbeneficial gene changes after eating broccoli.

But Mithen says the finding does not mean that only 50% of peoplederive a benefit from broccoli.

"It may mean that people without the gene need to eat a bit morebroccoli to get the same benefits," he says. "But the good news isthat nobody has to eat huge amounts. A few portions a week seems tomake a big difference."

Benefits Not Proven

National Cancer Institute researcher Richard B. Hayes, PhD, saysthe new research strengthens, but does not prove, the hypothesisthat a healthy diet can protect against prostate cancer.

Hayes' own 2007 study suggested a link between a high intake ofcruciferous vegetables - especially broccoli and cauliflower - andprotection from aggressive prostate cancer.

"There is a fairly consistent body of evidence suggesting thatfruits and vegetables are protective against many cancers and otherdiseases," Hayes tells WebMD. "But it may be stretching the pointat the moment to say that broccoli prevents prostate cancer."

Hayes says the suggestion that any one compound or group ofcompounds is responsible for the protective benefits seen in animaland epidemiological studies is premature.

"We can too easily go down that road of looking to develop a pillbased on this compound or that compound to protect against cancer,but the truth is we may never find that," he says.