Contrary to what diet gurus day, there is no single bulls-eye diet. There are many bulls-eye diets. Weston Price described about two dozen of them. None were vegan. Are all possible bulls-eye diets omnivorous? Possibly.
There are thousands of non-essential nutrients in thousands of locations throughout the body. It is impossible to have optimal levels of all of these thousands of nutrients in all of these thousands of locations.
Some will be deficient in some places and some will be in excess in other places in the body.
Those that are deficient become conditionally essential in the context of optimal nutrition and optimal health.
Some of these nutrients will be nutrients that are richer in plant foods; some of these nutrients will be nutrients that are richer in animal foods, and some may even be exclusive to animals.
A completely plant-based diet, even if supplemented with vitamin B12, will over time run a person down. Is that why in just 5 months working at a store that sold supplements, I encountered six women, all long-term vegans, who looked wasted, who complained of having no energy, and who had diagnosed themselves with all kinds of problems from B12 deficiency to iron deficiency to adrenal insufficiency to hypothyroidism?
A completely animal-based diet may do the same. How did the Masai keep so healthy and fit, consuming only raw animal products, such as raw blood, raw milk, and raw meat, Dr. Price?