All three of these B vitamins are essential to the normal formation of hemoglobin, which carries oxygen from the lungs to tissues in the body, including the hair. Healthy and strong hair relies on a constant supply of blood and oxygen. A deficiency of these B vitamins is like cutting off the blood supply to your hair, leading to increased hair loss, damaged hair and slow re-growth. Best sources of vitamin B6 and B12 are protein-rich foods like meat, chicken, fish, eggs, pork and soybeans. Your best bet for sources of folic acid are leafy vegetables, orange juice, avocado, beets, broccoli, wheat germ and some fortified cereals.