"Healthier" seems like an overstatement. Eating less meat in general and more vegetables is for sure an healthy choice, but many factors are to take in considerations (frequency of consumption, meat quality, choice of lean or fat meat, size of portions, plate composition, etc.) if we're to establish the health benefice of any kind of food. I'm not saying that there is nothing to gain adopting a vegan lifestyle, but it is not a panacea either. The simplistic assertion that it will be healthier - for the mere fact that meat is substituted for some vegetal protein - is presumptuous and not true. Vegan and health aren't synonyms.