Previous studies have shown an association between high folic acid intake and a reduction in the immune system defenses needed to fight viral infections and cancer. In a new study in mice published in the Journal of Nutritional Biochemistry, scientists at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University (HNRCA) set out to determine if excess folic acid intake caused adverse changes in the immune system.
Their study in aged mice indicates that high folic acid intake causes lowered immune function because natural killer (NK) cells, a particular type of immune cell, are less effective. NK cells are important for defense against viral infections and cancer because they identify and attack infected cells. Impairment in their function may lead to increased susceptibility to certain diseases such as viral infections and cancer. They are particularly important in the elderly because immune system function diminishes with age, making the elderly more susceptible to infections and cancer.