Mushrooming Immunity

Worried about a cold or some other infection? Maybe you should stock up on mushrooms.

These fungi can significantly enhance the body's immune response, according to a pair of fascinating talks I sat through today at the Experimental Biology '07 meeting. Although the reported experiments had been conducted in animals, the researchers acknowledged that their work had been prodded by hopes that the same will hold true in humans. And the fungi that proved especially potent in this regard? Those prosaic white buttons that account for 90 percent of the fungi eaten in the United States.

Dayong Wu and his colleagues at USDA's Jean Mayer Human Nutrition Research Center on Aging at Tufts University in Boston described his group's work with young-adult mice. They added a dry powder made from button mushrooms to the rodents' diet for 10 weeks in quantities that amounted to either 2% or 10% of the animals' meals. Other mice got just the unadulterated chow. When later stimulated with a compound that challenges the immune system, mushroom-treated mice had a more robust response. They produced higher amounts of certain immune agents known as cytokines (including some interferon and interleukin molecules and tumor-necrosis-factor alpha).

The finding suggests that for the elderly or others who might have weakened immune systems, one might enlist mushrooms as a dietary agent to shore up the body's defense against infections.

In a second study, Sanhong Yu and her colleagues at Penn State University tested the ability of five mushrooms widely available in U.S. groceries--including crimini and shitake species--to similarly rev up the immune response of activated macrophages. These are a type of white blood cells that are important immune-system players.

All of the fungi proved helpful, Yu reported. But the really big performer? White button mushrooms!

Yu's team then fed these mushrooms as 2% of the diet to mice for a month and showed that when challenged with a synthetic infection, the animals' immune systems again performed more heroically than if they had been dining on mushroom-free chow.

Who knew? Up to now, I'd always thought of mushrooms as more of a garnish for salads than as a health food.