I suppose the error lies in statements like "Everybody should eat X." "Y is making you Z." where the whole of the population is treated as one. Yet, we are

I suppose the error lies in statements like "Everybody should eat X." "Y is making you Z." where the whole of the population is treated as one. Yet, we are different. Our metabolic balances differ. Some persons lack certain genes needed to process certain substances. Other persons are super efficient at that and need more of some substances. "One size fits all." does not work in nutrition!