Guys he might just be kidding <| sep |> Of course it is nonsense that vegans can ' t get sick . What is not nonsense is that on average they seem to get fewer infections and when they do , they get over them a lot quicker . There are several scientific models to explain that . The one I found most compelling is the one about Endotoxins . Endotoxins are basically the remains of dead bacteria . They are not inheritably harmful but when they get into the bloodstream the immunesystem will attack them , even though they are already dead . By giving your body a constant stream of those , it will always be rather busy getting rid of them . And if you get a real infection in the same time , the immunesystem cannot direct it ' s full attention to the real threat as it already is busy . The intestinal walls are what is supposed to keep the endotoxins out and prevent it from getting into the blood stream . Different types of bacteria colonize it and care about different stuff . What has been found is that the bacteria that thrive on fiber also happen to be protective against the endotoxins . Couple that with the circumstance , that animalproducts usually are much more laden with dead bacteria than plantfoods and you get an idea who ' s immunesystem has to deal with more endotoxins and thus has less time to care about other stuff . There ' s plenty more things potentially playing a role in that . I think nutritionfacts . org might offer some more explanations for that phenomenon .