Prostate cancer: Foods that help

Once you remove the politics, federal health minister Allan Rock and Alliance Party founder Preston Manning have much in common. Both are 50plus men who recently underwent surgery for prostate cancer.Both Rock and Manning are alike in one other respect-they are young to have the disease. Most prostate cases are men older than 65. In Canada each year, 20,000 men are diagnosed with the disease. One in three will die, according to the statistics.  

The prostate is a walnut-size gland at the neck of the bladder. Its main function is manufacturing the fluid that carries sperm.

There is no known cause of prostate cancer. But a number of recent scientific studies are looking closely at the role of diet and nutrition in preventing the disease. Dr. Peter Gann is an associate professor at the Northwestern University Medical School in Chicago and a cancer prevention researcher. He appeared at a recent seminar on men’s health in Toronto sponsored by Roche Vitamins.

“We have recently found evidence of a possible reduced risk of prostate cancer linked to three compounds which are anti-oxidants and are primarily found through our diet-selenium, vitam E and lycopene,” says Dr. Gann.

Lycopene in tomatoes
He says the most promising of these three compounds is lycopene, which is present in tomatoes and tomato based foods. The highest concentration is in processed tomatoes, such as tomato paste, cooked tomatoes, pasta and pizza sauce, tomato juice and soup-even ketchup.

Lycopene is also present in grapefruit, watermelons and papayas and guava tropical fruits.

“It makes a difference if you cook it. Cooked is better. And it’s better to eat it with oil. It’s a fat-soluble compound that’s absorbed better. The Mediterranean diet, tomato sauce with olive oil is ideal. Fresh tomatoes will not give you the same amount of lycopene. In fact, some tomato juices that are highly processed may not give you the same level as others,” according to Dr. Gann. 

The way he describes lycopene gives an image of munching pac-man molecules coming to the rescue.

“Lycopene in the test tube appears to be more potent at crunching free radicals, the agents that are generated through the diet or by radiation. These are high-energy compounds that give off energy to our proteins and to our DNA. In the process of doing that, they damage them. Lycopene structurally is built in such a way that it has a very potent ability to engage these free radicals,” says Dr. Gann.

Diet guidelines
He has some suggested guidelines for men about how much lycopene they should take to get this beneficial effect.

“At this point, it’s prudent to suggest if men can incorporate tomato foods in their diet 3 to 4 times a week, that would be the recommendation. We clearly don’t have enough evidence yet to suggest that this is going to have any effect on prostate cancer or anything else. But since we’re not talking about an unpopular food, it’s not an unreasonable recommendation,” he says.

So far, the most convincing evidence for lycopene is from a study done several years ago with 40 thousand men who reported they consumed tomato sauce two to four times per week. This group has a 34 per cent reduction of prostate cancer risk. But more careful study is required says Dr. Gann, not only of lycopene but of selenium and vitamin E, other anti-oxidants found in food.

In studies with the latter two compounds, there also seemed to be a link to a decreased incidence of prostate cancer, but the link is not scientifically firm. Dr. Gann says plans are underway for other trials that will look carefully at the role of these anti-oxidant compounds and safe doses. But many questions remain to be asked.

What causes disease
“We’re beginning to learn that chronic inflammation of the prostate is far more common as men age than was realized. And inflammation of any sort, but particularly of the chronic type, generates a very large amount of free radicals. So one possibility is that these go on to damage the prostate cells which are capable of going on to become tumours. We’re working on studies that will tell us whether lycopene or any other agent can cause either a stop or reversal in this progression,” according to Dr. Gann.

As a scientist, he is careful not to say anything that might lead men to consume great amounts of foods or supplements containing anti-oxidants. Dr. Gann says it’s possible you can get too much of a good thing. In one Finnish study with selenium, he says the prostate cancer risk decreased, but the high doses actually increased the risk of lung cancer.

Research and money
And with lycopene–“If men decide that they’re going to consume lycopene and end up eating double stuffed pizza three to four times a week, we’re going to have a lot more problems than we’ll avoid. So it’s got to be part of an otherwise healthy diet,” he says.

“It’s not at all clear that the ultimate public health recommendation is going to be supplementation versus simply eating a whole food. It may be that there are interactions with other compounds in the whole food that are essential to get the health benefit. We don’t know that yet,” he concludes.

In the meantime, John Blanchard says the high profiles of Allan Rock and Preston Manning  are welcome publicity for prostate cancer. The president of the Prostate Cancer Research Foundation of Canada says government funding for prostate cancer research amounts to only a million dollars a year, or about $50 per new case.

It is not nearly enough, he says, for a disease that is the most common cancer in men, affecting one in eight.