Keeping dairy, eggs and fish oil or even fish will be good for amino acids. Otherwise, when the body calls for a specific amino acid, it pulls it from your muscle mass by metabolizing some of your muscle mass. The need for a full complement of amino acids is more important for those with weakened nervous systems/brains.

There are many cases where a mother fed her infant child a completely vegan diet, a few including no breast milk using a substitute vegan formula, where the child either died or failed to develop properly, especially neurologically.

It suggests to me that we need to be careful to get all the proper nutrition.

A modified vegetarian diet appears to be advised by many professionals.