Nisin is a naturally occurring alternative to many commercial preservatives. It does not appear to be toxic in any animal studies, however, human research is lacking. Nisin when administered regularly may modulate the microbiome in complex ways, which may or may not be beneficial to the host. For example, it may fight off harmful bacteria but it may also cause beneficial compounds in the gut to decrease. However, these changes appear to be reversible and would not likely occur from the small amounts used in food products.