Whey is a liquid byproduct of the cheese production process and is rich in protein.
Researchers found that when they treated human prostate cells in the lab with whey protein, the levels of an antioxidant called glutathione rose dramatically. Antioxidants like glutathione are thought to fight cancer-causing free radicals.
Free radicals are formed when oxygen interacts with certain molecules in the body. Their chief danger comes from the damage they can do when they react with cells -- called oxidative stress. Cells may function poorly or die if this occurs. Antioxidants defend the body against this free radical damage.
"The buildup of free radicals is associated with the onset of many chronic illnesses, such as heart disease and cancer," says researcher Joshua Bomser, assistant professor of food science and technology at Ohio State University, in a news release. "And human prostate tissue is particularly susceptible to oxidative stress."
For the study, which appears in a recent issue of Toxicology in Vitro, researchers treated human prostate cells with two different concentrations of whey protein for 48 hours in the lab and then measured the levels of glutathione in the cells.
The results showed that both doses of whey protein increased glutathione levels by at least 60%. The more concentrated dose raised glutathione levels by 64%.
"The small difference in glutathione levels between the two whey concentrations suggests that it may not take much whey protein to get an effect in the prostate cells," says Bomser.
Researchers say whey protein contains the amino acid cysteine, which is a key ingredient for producing glutathione in the body. By increasing the body's production of glutathione, they suggest that whey protein may aid in prostate cancer prevention, but more research on this is needed in humans rather than test tubes.
Whey protein supplements are popular among body builders but most people in the U.S. get enough protein from their diet. But good sources of cysteine are poultry, wheat, broccoli, and eggs.
"In diseases like cancer, there's usually a reduction in the body's overall capacity to deal with oxidative stress," says Bomser. "Keeping antioxidant levels elevated through diet and supplementation may prevent the development of chronic disease."