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How does food affect prostate cancer?

How does food affect prostate cancer?

Updated: 12/21/2015

Scientists from around the world are studying diet as never before. They are trying to understand how specific foods work in the body and which enzymes are impacted by our food choices. For patients with prostate cancer, scientists are searching for foods or nutrients that boost disease-fighting enzymes and help the body ward off this disease.

Exploring the Behavior of a Crucial Enzyme

Bill Nelson, M.D., Ph.D., an oncologist at Johns Hopkins Medicine, has been studying the behavior of a crucial enzyme called glutathione S-transferase Pi 1 (GSTP1) and the problems that result when it fails to protect prostate cells from harmful outside forces that can eventually cause prostate cancer.

Dr. Nelson was the first to discover GSTP1's role in prostate cancer. If cancer is a chain reaction, a genetic mistake or mutation that leads to another, then what happens to this enzyme is probably among the very earliest events. One or more genetic enemies (outside factors that cause the body's defenses to break down) attacks GSTP1.

The enzyme, which is apparently all that stands in the way of prostate cells and potentially toxic agents, doesn't put up much of a fight. Eliminating GSTP1 makes prostate cells vulnerable to cancer because it strips them of their defenses. Without this cancer-fighting enzyme, it’s much harder for prostate cells to detoxify carcinogens.

Dr. Nelson wanted to try to reverse the effect of GSTP1 being attacked by bad environmental agents. If the process could be simulated, perhaps he could identify a dietary equivalent to the Charles Atlas plan that would build up the enzyme so that it could deter prostate cancer. He wanted to find out if it’s possible to use food, or some particular nutrient, as preventive medicine.

Beta-Carotene: A Cautionary Tale

From a health standpoint, the rich Western diet, which is high in animal fats and low in grains, fruits and vegetables, leaves a lot to be desired (See "The Western Dilemma"). But is there something we eat too much of or routinely omit from our diet that triggers cancer growth?

Scientists have studied beta-carotene’s ability to prevent lung cancer. In several case-controlled studies, scientists noticed that smokers who ate several fruits and vegetables seemed to be protected against lung cancer. The scientists honed in on beta-carotene, a nutrient that's abundant in vegetables. They wondered if beta-carotene could be a biomarker that lowers the risk of lung cancer. 

In early studies with lab animals, beta-carotene performed like a champ and seemed to protect against several kinds of cancers. Suddenly, beta-carotene became the hot new scientific flavor of the month. As a result, three separate beta-carotene supplementation trials were initiated. However, the trials revealed that beta-carotene failed to prevent lung cancer development. In fact, in two of the trials, it actually made things worse.

In spite of the issues with the trials, researchers proved that the test subjects who ate a lot of fruits and vegetables did better than those who didn't. It just wasn't necessarily beta-carotene that improved their health. Scientists at Johns Hopkins Medicine remain cautiously optimistic about several promising nutrients.

Potential Cancer Fighters

There are several promising candidates for study, including:

Lycopene: Lycopene is a carotenoid (an organic pigment made by plants) that has been tagged as a potential biomarker. Interest in lycopene started with a food frequency questionnaire taken by men with fewer cases of prostate cancer who reported eating foods with tomato sauce. This led scientists to hypothesize that the lycopene in tomatoes might be better absorbed by the body when heated.

Researchers are exploring lycopene’s effect on antioxidant activity and the communication between cells. So far, animal studies and laboratory research have revealed that lycopene may help lower the risk of skin, prostate, lung, breast and liver cancers. Clinical trials investigating lycopene’s ability to lower cancer risk have had mixed results.

Green tea: Some components of green and brown tea, including catechin, epigallocatechin gallate (EGCG) and epicatechin are being studied for their biologically active properties. Using population studies, scientists are trying to determine if the consumption of large amounts of green tea is the reason why Asian men report fewer cases of prostate cancer. Laboratory and animal studies have shown that green tea can help slow the growth of cancer cells. Results from clinical trials suggest that green tea catechins may lower the risk of prostate cancer in men who have a high risk of developing the disease.

Soy: Soy contains cancer-fighting products called isoflavones, including one called genistein. Laboratory studies have shown that this compound can hinder the pathways in prostate cancer cells that contribute to the spread and growth of these cells. As a prevention method, soy has helped lower PSA levels in some clinical trials. Some studies have shown that soy may help prevent and treat prostate cancer. One clinical trial helped demonstrate how regularly consuming a soy drink may help slow the progression of prostate cancer. In two clinical trials, a soy isoflavone supplement was given to prostate cancer patients receiving antiandrogen therapy to diminish side effects such as sexual dysfunction and changes in mental functioning. However, the soy supplement did not seem to improve the side effects of antiandrogen therapy.

Sulforaphane: This compound, found in cruciferous vegetables, may be instrumental in defending against several cancers by turning up the body's production of protective enzymes. Clinical trials are being conducted to see how this compound might be used to reduce the risk of prostate cancer progression.

What Not to Eat

Muscle meat that is grilled or fried at high temperatures is known to produce carcinogens such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). The reaction of amino acids, sugars and creatine found within the meat create HCAs. PAHs are contained in the flames that form when meat juices and fat drip onto an open fire. During the cooking process, PAHs stick to the surface of the meat. According to the National Cancer Institute, these carcinogens can create changes in DNA that may increase the risk of cancer in some patients.

Bottom Line: Eat more fruits and vegetables

So what should you be eating or avoiding to reduce your risk of prostate cancer? Eat plenty of fruits and vegetables and consume less red meat. Beyond that, keep up with the latest published laboratory and clinical trial research to see which alternative treatments might work for you.


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