The typical American diet is high in omega-6 fatty acids, which are found in products including corn oil.
In lab tests, researchers exposed human prostate cancer cells to arachidonic acid, a common type of omega-6 fatty acid. Those cells grew about twice as quickly as prostate cancer cells not exposed to arachidonic acid.
The omega-6 fatty acid apparently signaled a set of genes to spur the tumors' growth, write Millie Hughes-Fulford, PhD, and colleagues.
Hughes-Fulford directs the cell growth laboratory at the Veterans Affairs Medical Center in San Francisco.
Stopping the Chain Reaction
The omega-6 fatty acid apparently signaled about a dozen genes to make prostate cells grow faster than normal, the researchers write.
The researchers added a nonsteroidal anti-inflammatory drug (NSAID) to the omega-6 mix. That slowed down the cells' growth.
Reducing the "abnormally high" dietary levels of omega-6 fatty acids may help slow prostate cancer's progression, write Hughes-Fulford and colleagues. They suggest further drug studies to evaluate the cancer cells' growth process.
Prostate cancer patients weren't included in the study. The researchers are currently testing different diets on animals to see if fatty acids affect tumor growth.
Getting Back in Balance
Consumption of omega-6 fatty acids has changed in the U.S. and other Western countries over the last half-century, write Hughes-Fulford and colleagues.
Fifty years ago, people in Western nations consumed about twice as much omega-6 fatty acids as omega-3 fatty acids, which are found in certain fish (such as salmon), walnuts, flaxseeds, and canola oil. Now, typical intake of omega-6 fatty acids is 25 times higher than that of omega-3 fatty acids, the scientists note.
In short, the balance between omega-6 and omega-3 fatty acids isn't what it used to be.
Hughes-Fulford -- who is also an adjunct professor of medicine at the University of California, San Francisco -- doesn't claim to have prostate cancer all figured out. She's not promising that any particular diet will put the brakes on the growth of prostate cancer, which usually happens slowly.
"I'm not a physician, and do not tell people how to eat," Hughes-Fulford says in a news release. "But I can tell you what I do in my own home. I use only canola oil and olive oil. We do not eat deep-fried foods."