Ask the Doctors

Dear Doctor: Can white button mushrooms help control my blood glucose? I saw some headlines about this a while back, but it sounds like a correlation to me -- not a clear cause and effect. Maybe it's just that people who eat more mushrooms also eat less junk food?

Dear Reader: Spoken in the true scientific spirit. You are indeed correct that how we view the results of a study depends, in part, on how it is structured. In this case, we're talking about a mouse study in which researchers from Penn State's College of Agricultural Sciences looked at whether a diet that included daily servings of white button mushrooms would affect the gut microbiomes of laboratory mice.

What edges the results of this particular study into the realm of cause and effect is the use of two different groups of mice. One group included typical laboratory mice with a normal gut microbiome. The second group, however, was made up of germ-free mice who did not have a gut microbiome. That allowed the scientists to observe exactly how the microbiota of the "normal" mice changed as compared to the control group.

What they found was that eating a daily serving of white button mushrooms caused subtle changes to the makeup of the gut microbiome in the normal mice. Specifically, adding the mushrooms to their diets resulted in a rise in the overall numbers of a specific bacterium. Known as Prevotella, it produces certain short-chain fatty acids that have a positive effect on genes that improve glucose management.

What's interesting is that the function of the mushrooms in this case was as a prebiotic. That is, they served as food for the community of tens of millions of bacteria that make up the microbiome. For reasons that are not yet fully understood, the mushrooms allowed the Prevotella to flourish, which translated to a measurable effect on blood glucose management in the liver.

The results of the study invite future research into strategies to prevent and manage diabetes, a chronic and progressive disease in which the body cannot properly metabolize glucose. That's important, considering that more than 30 million Americans -- close to 10 percent of the population -- are now living with diabetes, and an estimated 1.5 million new cases are diagnosed each year. Diabetes, which increases the risk of heart attack and stroke, was the seventh-leading cause of death in the United States in 2015.

Another intriguing aspect of this study is the new light it sheds on the effect our diet can have on the populations within the gut microbiome, and how those microbial communities affect the workings of our bodies.

As for whether eating white button mushrooms can help you with your own blood glucose management, it's too soon to say. This study was conducted in mice and for a definitive answer, a human study is needed. According to the researchers in this study, the portion size fed to the mice translates to about 3 ounces of mushrooms per day for us humans. There's no reason not to add a portion of white button mushrooms to your daily diet, barring an allergy, of course. Just don't saute them in a lot of butter.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

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