One argument against a vegan diet is the reported deficiencies of vitamins B12 and D and the minerals calcium and iron. Vitamin D deficiency would not be a problem if we didn't wear clothes. Supplements are a socially acceptable alternative to coprophagy and nudity. It is those who eat meat who need extra calcium. Since menstruation whilst breast-feeding is rare, a major cause of iron deficiency is removed.
Gorillas also eat the placenta to recover minerals.
Modern carnivorous society then imposes abnormal conditions on vegetarians and vegans and it is realistic for them to compensate with supplements. Conclusions Dr Ryde concluded by stating his hypothesis that Pliocene man was a herbivore food gatherer, an opportunist carnivore and perhaps a coprophagist. Adverse climatic changes and control of fire led to an exploitation of carnivorous options. Currently we are still adapting, for better or worse, to the nutritional changes deriving from the creation of agriculture, animal husbandry and a food industry. Modern man's destructive and addictive habits and minimal physical activity are unphysiological, productive of excess weight and disease and lead to early degenerative changes.