On Turkey Day, Give Thanks for Tryptophan—Sincerely, Your Immune System

OK, time to stifle the Thanksgiving jokes about turkey making you drowsy. Yes, there’s an amino acid called tryptophan in turkey, and it does help your body produce a chemical called serotonin, which promotes a good night’s sleep. But chicken, beef, nuts, and cheese also contain tryptophan, and no one’s pointing the finger at them. So if you nod off after dinner, it’s probably due to all the carbs in that pile of brown-and-serve rolls you scarfed down.

After years of taking a bad rap as a sleep aid, it’s time for tryptophan to get the respect it deserves — because it’s really important to your immune system. In fact, researchers at Roswell Park’s Center for Immunotherapy want to help cancer patients’ immune cells get a hearty helping of tryptophan so they’ll be strong enough to fight the disease.

“Immune cells are highly dependent on tryptophan,” explains Kunle Odunsi, MD, PhD, Deputy Director of Roswell Park Comprehensive Cancer Center, Chair of the Department of Gynecologic Oncology, and Executive Director of the Center for Immunotherapy. “If they don’t see it, they die.”

Cancer cells use this weakness to their advantage by turning on an enzyme called indoleamine 2,3-dioxygenase — IDO for short — which starves the immune cells of tryptophan and “puts the brakes on the immune system,” explains Odunsi. When that happens, voilà — cancer cells can reproduce and spread without interference.

Odunsi and his colleagues are using that knowledge to develop more effective cancer-treatment vaccines, especially those targeting ovarian cancer. They are among the first researchers to combine vaccines with agents that can prevent IDO enzymes from cutting off the immune cells’ supply of tryptophan.

“When we block IDO enzymes, more tryptophan becomes available for the immune cells,” he says. “They are happy and are able to do their job fighting cancer cells.”

So when you sit down to the Thanksgiving feast this year, raise your fork to tryptophan and the power of your awesome immune system!