Strict vegans are at risk of vitamin B12 deficiency because vitamin B12 is predominantly found in animal products like meat, dairy, and eggs. Since vegans do not consume animal-based foods, they often require supplementation or fortified foods to meet their vitamin B12 needs. Vitamin B12 is essential for the production of red blood cells, the maintenance of the nervous system, and DNA synthesis. A deficiency can lead to anemia, nerve damage, and other health issues.