Although strands of hair are not alive once they are outside of the scalp, the root is. Just like any other part of the body, hair roots require proper nutrition, including vitamins, to grow healthy hair strands. Vitamin deficiencies can cause slow hair growth and even hair loss. However, if you are not deficient, there is little evidence that taking additional vitamins will increase hair growth. You can use vitamin supplements to increase the amount of hair-growing vitamins in your body, but you must follow the daily international unit dosage recommendations to avoid overdose.
Biotin, also known as vitamin B7, is essential to the growth of nails and hair. A biotin deficiency can result in weak, brittle hair and hair loss. Biotin supplements are effective at promoting hair growth wen there is a biotin deficiency, but there is little evidence that taking more than necessary increases hair growth. The recommended daily dose for biotin is 30 IU. Lactating women should increase their intake to 35 IU.
Vitamin A is an antioxidant that protects hair follicles from the damaging effects of free radicals. These molecules break down hair follicle cells, decreasing the amount of nutrients that get to the bulb of the hair shaft. This leads to dry hair and slow her growth. The daily dose of vitamin A is 900 IU for men, 700 IU for women, 770 IU for pregnant women and 1,300 IU for breastfeeding mothers.
Vitamin E is another antioxidant that protects hair follicles form free radical damage. It also keeps hair follicle cell membranes moisturized and elastic, allowing hair to grow to it's full potential. The recommended daily dosage for Vitamin E is 22.4 IU. Women who are nursing should increase their vitamin E dosage to 28.4 IU.
Vitamin B12 is also known as cobalamin. It assists with the creation of red blood cells and helps the body convert food into energy and utilize nutrients such as iron, protein and fat. Without vitamin B12, hair does not get all of the nutrients it needs to grow. The daily recommend dose of vitamin B12 is 2.4 IU for men and non-pregnant women, 2.6 IU for pregnant women and 2.8 IU for women who are lactating.