Researchers at the National Institutes of Health observed rapid and distinct immune system changes in a small study of people who switched to a vegan or a ketogenic (also called keto) diet. Scientists closely monitored various biological responses of people sequentially eating vegan and keto diets for two weeks, in random order. They found that the vegan diet prompted responses linked to innate immunity — the body’s non-specific first line of defense against pathogens — while the keto diet prompted responses associated with adaptive immunity — pathogen-specific immunity built through exposures in daily life and vaccination. Metabolic changes and shifts in the participants’ microbiomes — communities of bacteria living in the gut — were also observed. More research is needed to determine if these changes are beneficial or detrimental and what effect they could have on nutritional…