My dad has to have vitamin B12 injections and calcium tablets because being a vegan doesn't provide the required nutrients. All of the long term vegans I know have deficiency-related health problems. Vegans in less developed countries obtain additional nutrients from insects etc in their food, but our food is blasted with chemicals and insect free, so vegans in developed countries often have diets lacking in important nutrients. I understand why someone is vegan from an ethical point of view, just don't pretend it's a healthy option.