You have about 300,000 scalp hairs, of which 100 to 150 are lost each day. But hair breakage is not the same as normal hair loss. Any number of factors may be the culprit, even your hair's genetics, notes a study cited in the "Journal of Investigative Dermatology." But smart hair care practices and good nutrition, including vitamins, may benefit all hair types from damage. As with all supplements, consult your doctor before use.

Strong hair starts at the roots. Each shaft of hair comes from a follicle that lies in the dermal layer of skin, just below the surface. A good supply of blood vessels nourishes the follicles, making the shaft strong and healthy and more able to withstand external damage, such as brushing, hair blowing and styling. Vitamin C plays an integral part in collagen production, which forms the structure of blood vessels. Vitamin C is also an antioxidant that fights free radicals that may cause cell and tissue damage. The recommended dietary allowance, RDA, of vitamin C is 90 mg per day.

The two types of vitamin D are vitamin D-2, which is synthesized by plants, and vitamin D-3, which your body synthesizes when exposed to sunlight. Your body contains vitamin D-3 receptors that allow vitamin D-3 to be utilized, states a 2006 study in the journal "Endocrinology." This interaction is important to keratin production. Your hair is comprised of the protein keratin housed within dead cells. Your hair's strength depends on adequate keratin production and may help defer breakage. The RDA of vitamin D is 600 to 800 IU per day.

Biotin, or vitamin B-9, is essential for healthy hair. A study in the journal "Pediatrics" documents a biotin deficiency in a child fed raw eggs. This child presented with complete hair loss. It was discovered that the raw eggs pulled biotin out of the child's system, causing the loss of hair. With removal of the raw eggs from the diet, biotin supplementation was introduced, and the child's hair grew back completely, leaving the researchers to conclude the importance of biotin in the development and growth of strong hair. The adult RDA for biotin is 30 mcg per day.