The medical literature has numerous articles on dietary products that affect the immune system. Chocolate and mushrooms are two that stand out.
Chocolate is widely reported to be an anti-inflammatory with cardiovascular benefits. Other research shows that cocoa extracts can stimulate immune response, including pro-inflammatory cytokines. Mushrooms are also reported to either “modulate” or stimulate immunity. So what do chocolate and mushrooms really do to the immune system?
Ideally, we would like for our immune systems to operate in the Goldilocks zone of just the right amount of inflammation, immune cell proliferation, and other parameters. Too much immune activity produces inflammatory and auto-immune diseases; too little leaves us vulnerable to infectious disease. Our diet clearly affects all aspects of health, so we may reasonably expect that some nutritional products contribute to regulation of the immune response.
Most of the research has been done on cell cultures or animals. I found one clinical trial of interest. Researchers at the Memorial Sloan-Kettering Cancer Center, New York, gave Maitake mushroom extract orally in a range of doses to breast cancer patients who were free of disease after initial treatment. They found both stimulatory and inhibitory effects on immunologic parameters measured in peripheral blood. The effects depended on the dose, in the range of 0.1 to 5 mg/kg. For many of the measurements, intermediate dosages had more effect than either high or low doses. The researchers conclude that cancer patients should be aware that mushroom effects can be more complicated that what we would think based on lab research.
In a lab study of cocoa extracts, a team at the University of California, Davis, found that flavanols and their oligomers, the procyanidins, stimulate the innate immune system and early events in adaptive immunity. This team isolated biomolecules of different sizes from the cocoa, and found that different cocoa molecules have different effects on the immune cells in lab dishes.