Doesn't that mean there is a quality (and quantity) to nutrition and not just subsisting, that we need to examine? And the claim about meat is that it has a quality that is beneficial.
What societies in the past have mainly been vegetarian? None except India seem to persist to this day. I hear the human race took a pretty big hit in the early agricultural era as far as life expectancy goes.
https://www.sciencedirect.com/science/article/abs/pii/S02615...
>Health outcomes associated with vegetarian diets: An umbrella review of systematic reviews and meta-analyses
>Conclusions: Vegetarian diets are associated with beneficial effects on the blood lipid profile and a reduced risk of negative health outcomes, including diabetes, ischemic heart disease, and cancer risk. Among vegetarians, SDA vegetarians could represent a subgroup with a further reduced risk of negative health outcomes. Vegetarian diets have adverse outcomes on one-carbon metabolism. The effect of vegetarian diets among pregnant and lactating women requires specific attention. Well-designed prospective studies are warranted to evaluate the consequences of the prevalence of vitamin B12 deficiency during pregnancy and infancy on later life and of trace element deficits on cancer risks.