Quote Originally Posted by Thorne View Post
There are some nutrients that we get primarily from the consumption of meat products. I'm not an expert so I won't try to explain which nutrients they are.
I am (well, a degree in biochemistry plus some study of nutrition theory) so I will. They're mainly amino acids, the components of proteins: since we're made of meat, the easiest way to get the amino acids we need for our proteins is to eat meat. Most vegetable foods don't have the right mix. However, by a happy accident or the goodness of Gaia, if you eat both grains and pulses (as in such classic peasant foods as rice'n'peas, or just a peanut butter sandwich) the amino acids that are missing from one source are present in the other, and you end up with a pretty good balance.

The other main things you miss in a purely vegetable diet is fats and Vitamin B12. Ian's daughter was probably lacking B12, a deficiency that takes a long time to show up; even the Vegan Society admits that the only way to make up the lack is synthetic supplements, either as pills or artificially fortified foods.

But it's worth considering that for most of human history the vast majority of people ate very little meat. The idea of ancient diets as consisting of whole chickens and legs of pork, so far as it has any basis in fact, is based on the lifestyles of the upper 1%. And this is one reason people are so attached to their meat diets: it's a very ancient status symbol to be able to eat lots of meat, so the idea that it must be good is hard to shake. But exactly the same was true of white bread, and it's taken us a couple of centuries, once white bread became widely available, to recognise widely that it's actually not very good for you.