Some people can live as vegans, but lots of us cannot. I eat vegan but add meat! Lol. (Keeping kosher means we don’t mix dairy and meat). My MD is an integrative practitioner and he says that his vegans get pretty sick eventually.
Well, there are a whole lot of vegans out there that are only concerned about animal rights and do not know the first thing about nutrition. These are probably the people your doctor is talking about. Health focused vegans, or “plant-based, whole food” vegans are among the healthiest people in the world. Virtually no heart disease, no diabetes, very low cholesterol levels. Good blood pressure. Like I said, literally the best thing I’ve ever done for myself. You could not pay me to live any other way.