 You'll note in this study of 15,000 American vegetarians. Not only did eating vegetarian appear to have a favorable effect on the prevalence of allergies, but several chronic diseases as well. This is what they're referring to. After controlling for factors like smoking rates, vegetarians were found to have significantly less coronary artery disease, fewer strokes, less high blood pressure, less diabetes, less diverticulosis, etc., and significantly fewer diseases overall. They also noted that the non-vegetarians were more likely to have gone in for surgery, for things as varied as varicose veins and hemorrhoids to even more hysterectomies, as well as more likely to be on medications. Those eating meat had about twice the odds of being on aspirin, sleeping pills, tranquilizers, and acids, painkillers, blood pressure medications, laxatives, and insulin. So if you don't like taking drugs or don't like paying for drugs, we may be able to cut our odds of needing medications in half by choosing to eat vegetarian.