Vegans cannot get enough protein from a plant-based diet to maintain proper health.
Humans need for about 6% of their diet to be comprised of protein, though most doctors recommend 9% just to be sure. Many nuts and vegetables contain enough protein to meet this nutritional requirement, so plant-based diets provide adequate protein for human health.
There is no credible science that equates a plant-based diet with protein deficiency. Moreover, we are not facing a kwashiorkor epidemic among vegans or anyone else in developed and developing nations, but we are facing both diseases and chronic health problems associated with the consumption of excess protein. It is also noteworthy that people have been thriving on a plant-based diet throughout history, and more people are choosing to do so every year without suffering from a protein deficiency. Other factors being equal, vegans have been and continue to be at least as healthy as their peers in this regard.