I know of a ayurvedic and herbal doctor who was righteous and poor and has been eating higher quantities of only washed and cleaned cheap raw vegetables with a pinch of salt for more than 40 years. He had not eaten even any grain or oil.
I first met him when he was 40 and then met him when he was 75. He had not changed a bit and was completely agile and active. All his hairs were black.
Pleasantly surprised but tauntingly I asked him that how scientifically the people can get enough Protein, Iron and Calcium from the vegetables for survival and strength in the long run.
He replied that is there anyone on the earth more powerful than the Elephants and Hippo or who has stronger and massive bones than them and that who can outrun and defeat the deers in short sprints or long distances.
I was stunned and wanted to talk about brain power but then I kept quiet because I new he had no less brain than me.
BTW this should neither be adopted nor propagated.