ALWAYS TAKE Vitamins as directed on the bottle and NEVER more than the stated dosage. Double dosages of a vitamin do not make it work twice as much and you can overdose on certain vitamins with dangerous effects. Some vitamins can cause unwanted side effects in individuals with certain medical conditions or intolerances. Consult your doctor if in doubt or taking other medication or you have any medical condition

Essential fatty Acids (EFA)
Are fatty acids that cannot be constructed by humans from other components by any known chemical pathways and thus must be obtained from the diet. There are two families of EFAs that are both generally essential and have a particular relevance in hair loss.

Omega-3 fatty acids -- play a key role in skin, hair, and nails. You should eat some of these foods, which are rich in omega-3, every day:

• Salmon, tuna, mackerel, and other fatty fish
• Flaxseed oil
• Walnuts and almonds

The Omega-6 fatty acid Gamma-Linolenic acid, is found mainly in plant based oils such as evening primrose oil, blackcurrant seed oil, borage oil, olive oil and hemp seed oil. It is sold as a dietary supplement for treating problems with inflammation and auto-immune diseases. The effectiveness regarding help in stopping hair loss is disputed. Some studies have shown effectiveness when taken orally and applied topically.

Vitamins A, B-6, B-12, C, E, Biotin and Folic acid
are also important to your hair. Vegetarians and vegans often don't get enough of these vitamins.

Adequate intake of vitamin A is vital in helping to promote the growth and health of cells and tissues throughout the body, including the hair and scalp. NOTE: It has been documented that too much Vitamin A can CAUSE HAIR LOSS. Prolonged vitamin A deficiency can lead to hair loss and dandruff caused by the buildup of cellular debris in the hair follicles. The body gets vitamin A in two ways: from plant sources in the form of carotenoids, such as beta carotene, that convert to vitamin A in the body. These sources include red, yellow, and orange fruits and vegetables as well as some dark green leafy vegetables. The body also gets vitamin A from animal sources in the form of retinol. Good animal sources include, liver, fish oil, eggs, fortified milk and foods fortified with vitamin A

A deficiency of B vitamins can cause reduced blood and oxygen supply to the hair, leading to increased hair shedding, damaged hair, and slow re-growth. Good sources of vitamin B-6 include bananas, potatoes, whole grains and spinach. Major sources of B-12 include meat, poultry, fish, kidney, eggs and dairy products.

Biotin, also known as vitamin H or B7 is a water soluble vitamin and is required in the formation of glycogen, and is also essential in the making of fatty acids. Biotin, found as an ingredient in many of today's shampoos and hair conditioners, is said to repair damaged hair and keep hair healthy. For most people eating a healthy diet, Biotin deficiency is rare. It can also be found in Brewer's yeast, liver and nuts

Vitamin C is essential to producing collagen, a connective tissue that gives structure by holding tissues in the body together, such as the tissue in hair. A vitamin C deficiency can cause the hair to be susceptible to problematic splitting and breaking. This usually only occurs with severe deficiency and can be reversed when vitamin C intake is increased. People who smoke need twice as much vitamin C as nonsmokers. Vitamin C is found in plant sources such as citrus fruits, berries, melons, peppers and tomatoes. 

Eating plenty of fresh fruits and vegetables -- especially citrus fruits and tomatoes -- will help you get folic acid. Folic acid is a form of the water-soluble Vitamin B9. Whole grain and fortified grain products, leafy vegetables, beans, and lentils, liver and avocado also contain folic acid.

Vitamin E is is a fat soluble antioxidant, that studies have shown enhances scalp circulation. Vitamin E appears to promote hair growth and a good hairline. It can also benefit hair growth by preventing dry-scalp and dandruff. The rich sources of Vitamin E are cold-pressed vegetable oils, green leafy vegetables, nuts like almonds, hazelnuts and peanuts, various oils like sunflower, wheat germ oil, soybeans, raw seeds and dried beans. 

In a prostate enlargement and prostate cancer research experiment, Vitamin E succinate (a salt or ester of succinic acid) was compared to the anti-androgen drug flutamide. While the addition of flutamide largely failed to combat growth stimulated by the addition of the dihydrotestosterone (See here for significance of this), vitamin E succinate, proved to be successful. However, when both compounds were added, a further repressing of DHT-mediated cell growth was observed. When tumor cells were replaced with cell cultures from normal prostate tissue, the same amount of vitamin E succinate only slightly inhibited cell growth, suggesting that the vitamin may selectively inhibit tumor cells that are androgen sensitive. In another experiment that sought to determine the effect of vitamin E succinate on prostate specific antigen, PSA expression was induced by the addition of DHT to the cell culture. When vitamin E was added, intracellular and secreted levels of PSA expression were repressed. This occurred together with down-regulation of androgen receptor protein levels. The androgen receptor is required for the initiation and progression of prostate cancer and Male Pattern Hair Loss. The authors say that vitamin E succinate may suppress the growth of prostate cancer and the expression of PSA "by inhibiting androgen receptor expression at both the transcription and translation levels."

Protein
is also critical for keeping hair healthy, but many people don't get enough. Lean meat like fish, chicken, eggs, and soy products are good sources of protein; eat one serving every day.

Magnesium, Copper, Iron, Zinc and Water
Because trace minerals like those above can also affect hair, it may be a good idea to take a daily multi-vitamin. Iron deficiency may be related to many forms of hair loss and recent studies indicate that people may need higher levels of iron stores than previously thought to re-grow hair. Iron deficiency is the world’s most common nutritional deficiency and is can be caused by inadequate dietary intake, excessive menstrual bleeding, and other forms of blood loss. Treatment of iron deficiency includes adequate dietary intake and, when appropriate, oral iron supplementation. 

Water is involved in the transport of vitamins, minerals, amino acids, and many other nutrients. Almonds are a good source of magnesium. Dehydration is a factor that stops growth of hair. A cause of dehydration is excessive intake of beverages like tea, coffee, etc. 

Cider Vinegar
Non-scientific case histories have shown that a few teaspoonfuls of cider vinegar daily for several months has halted hair loss and remaining hair has grown healthier and thicker. One reason for thinning hair is a deficiency of minerals salts. There is potassium in apple cider vinegar and this is essential for healthy bones, teeth and hair. Cider vinegar will not work the same way for everyone. A few people may be allergic to it and others may not be affected at all. Cider vinegar may be taken in a glass of water first thing in the morning or just before meals. 

Inositol
is not widely considered as having a major effect on hair. It has been added here due to the author's beneficial anecdotal experience. However, Inositol does has many good factors and is said to promote healthy hair and hair growth.

Inositol is not considered a vitamin itself because it can be synthesised by the body. Inositol is the common name for the most prominent naturally-occurring form called myo-inositol, the only form of Inositol utilised by the body as a nutrient. Inositol is a simple carbohydrate involved in the structural basis that are responsible for products such as glucose, glucuronolactone and water. Myo-Inositol is classified as a member of the vitamin B complex (referred to as vitamin B8)