Answer by Steven Fowkes:

One not yet mentioned is nucleic acid insufficiency. Animal products (dark meat, liver and other internal organs) are rich in nucleic acids, which are needed for countless metabolic pathways. People of certain metabolic types need high nucleic acid in their diet to be optimally healthy. Most do not. While you can get nucleic acids from yeast, many people cannot tolerate dietary yeast.
Another long-term risk is inflammation. Among vegan foods, the grains are the primary source of dietary acidity. So if you do not eat meat, you have to eat grain to balance your pH (unless you are a world-class athlete, in training). Grain is one of the most inflammatory foods that humans can eat. And in the USA, the super-wheat and GMO-corn grain products seriously increase that risk. In people with robust digestive systems, this may be a minor risk. But in this day of xenoestrogen chemical exposure, 100x lead burdens and micronutrient depletions, many people are not able to digest grain proteins sufficiently and experience chronic inflammation and leaky gut syndrome.
I’m sure that others can add to this list.

Besides risking B12 deficiency. What are the long term risks of excluding all animal products from your diet?