Which is a healthier diet: pescetarian or vegetarian? why?

Your choice: The most recent big studies show no differences between vegetarians and omnivores in any category of disease or in longevity when we control for other factors. Vegetarians can claim the moral high ground citing the cruelty of factory farming but a fish-eater can do so as well. Protein's more abundant, and your physician can advise on supplementing for either diet.