Many with autism have gut problems, and most of the time those gut problems are related to the bacteria in our guts. I certainly have gut problems, especially but not exclusively related to gluten, so you will on occasion read something on gut-related issues.
Which brings me to recent research that showed that there is a relationship between the kinds of bacteria present in the gut and degree of social bonding. While close social bonds will result in the easy spreading of pathogens, they will also result in the easy spreading of beneficial bacteria as well–which can in turn reduce the likelihood of getting pathogens. We also know that the greater the biodiversity of one’s gut flora, the healthier the gut.
Of course, if strong social interactions, including frequent touching, is necessary to maintain a strong immune system and a healthy gut, it should perhaps not surprise us that autistics have immune system and gut problems. Many of us are very sensitive to touch, especially human touch, and try to avoid it (either directly or indirectly), and this sensitivity can very considerably from day to day.
Social contact, stress physiology and gut microbiome are all intensely related. Your social contact defines how much stress you interact with, and both can influence the cocktail of microbes in your gut.