There are reports that prenatal vitamins can increase hair thickness and prevent hair loss.

Prenatal vitamins are different from regular multivitamins because they contain extra calcium, iron and folic acid. The latter is one of the B-complex vitamins available in many available hair-growth formulas.

Although no formal studies have been conducted, folic acid is reported to cause hair to grow faster and the strands to become thicker. According to several hair-loss experts and dermatologists, there are a number of vitamins that do the scalp good.

Biotin, B vitamins, iron and omega-3 fatty acids (such as omega-3 oil) are all necessary for proper hair, skin and nail health.

Saw palmetto has shown potential in treating benign prostatic hyperplasia, which is caused by the some of the same hormones that cause hair loss.

Samantha Heller, MS, RD, a nutritionist at NYU Medical Center said: "I believe there are many people who may have a sub-clinical lack of omega 3 fatty acids - these are 'good' fats, which have anti-inflammatory properties and may actually play a role in healthy hair."