Humans are omnivores, everyone knows this except the closed minded vegans. Yes, in the short run a vegan diet works, and a fruitarian works even better than vegan. But to state that humans optimally thrive on veganism is wrong in the long term.
My opinion on the best diet for humans meant to cure the incurables as I outlined in http://www.curemanual.com :
Diet must be 100% raw paleolithic diet. That is where many people fail. They just cannot do raw organic / wild meat. But it has to be done. Humans are true omnivores. I believe raw vegan is a mistake. Raw organic / wild animal food is the super food raw vegans are forever looking for, it’s right in front of them but they can’t acknowledge it because of their pride… most will not publicly state they were mistaken. Many vegans have careers and reputations at stake. Begin with raw organic fertilized eggs and raw organic fish. Then move on to land animals. See http://www.rawpaleo.com and http://www.rawpaleoforum.com for more information and practical support.
As long as you cook, any kind of cooking, even steaming, you are polluting yourself immensely. This must be understood by the sick.
The summary is this: the best, most effective diet to help cure people the fastest is a 100% raw paleolithic diet. Raw organic / wild fruits, raw organic / wild animals / ocean creatures, some raw / organic vegetables. Humans are true omnivores.