For generations, we have been taught that bacteria are pathogens that cause illness. The shocking truth is that your gut contains more bacterial cells than the rest of your body. Even more incredible, research reveals that these so-called "gut germs" keep us healthy rather than causing illness. At any given time, numerous strains of bacteria live in the human gut, and the gut, like a rainforest or a barrier reef, is a complex habitat. The gut microbiome refers to this bacterial ecosystem in the intestine.

Excess and deficiency of nutrients significantly impact gut microbial communities in rodents and humans, acting directly on the microbiota or indirectly via host physiology. Furthermore, the effects of diet on the microbiome in determining health or disease can vary significantly depending on the individual's age and environment.