The justification for this review article is to understand the position of vegans and those individuals who consume food of animal origin from an unbiased perspective but with a grounding in scientific evidence. This will provide people who eat meat with scientific and ethical arguments to defend their alimentary autonomy in the context of the moral conflict that has emerged in societies regarding the consumption of meat and animal products, which is criticized –sometimes even attacked– by activists, ovolactovegetarians, or vegetarians with alimentary habits that stress ethical and moral respect for animals. These individuals refuse to eat meat and animal products but sometimes show disrespect for those who do. In recent decades, veganism and vegetarianism have reached an apogee in some western societies where they are often considered a healthy option for humans that simultaneously fosters animal and environmental welfare. While those diets may provide numerous benefits, they can also entail health risks by failing to provide balance and necessary dietary supplements. Various researchers concur that they are not appropriate for pregnant women, children, or carnivorous or omnivorous pets. Our review of scientific articles in favor and against dietary regimens that lack protein of animal origin leads to the conclusion that these dietary changes, on their own, do not reduce animal suffering or the contamination generated by the meat, dairy, and poultry industries. Finally, it is important to consider that, despite the popular opinion that vegetarianism and veganism are healthy diet alternatives, the diet must be individualized and well-balanced according to each stage of their life cycle.