I gave up vegetarianism after 5 years of continuing ill-health. Despite lots of home-grown fruits and vegetables, with natural fertilisers, and home-made compost. We are without doubt evolved to eat some meat; as I remember from my long-ago Anthropology studies, the ratio among almost all peoples, of pre-industrialised societies was 80:20. The women traditionally grew or gathered the 80% - nuts, seeds, roots, berries, green vegetables, insects, shellfish. The men provided the rest, from the macho, often highly stylised hunting rituals. That ratio seemed to be the optimal for our successful evolution. It was the introduction of farming, cereals, domesticated animals that actually was both our pinnacle of success and our downfall. Tooth decay, altered facial structures from inadequate chewing, reduced jaw size, less efficient breathing ability. Make of it what you will. In the meantime, we live with our chickens, home-made compost, composting loo (human waste, properly and safely composted, makes the most amazing encourager of plant growth - not on food crops, though, for obvious reasons. Home grown fruits and veges, avocados and citrus, olives and figs, locally-produced olive or avoacdo oil. meat twice a week, fish at least once. I've never been so healthy.