Your hair makes a personal statement about yourself. Changes in hair color or length often are considered to be major personal decisions and can affect self-perception, as well as how others view us. If hair changes occur that are not by your design, it can be unsettling. This is especially true for hair loss. Although hair loss is rather common in adult men, when hair loss occurs in women, it can be particularly distressing.

Question: What are the common causes of hair loss in women?

Answer: Most research on hair loss in women links it to hormonal imbalances. In particular, one of the most commonly studied hormonal causes of female hair loss is high levels of the male hormone, testosterone. A woman’s body naturally produces testosterone, and much of it is normally converted to the key female hormone, estrogen. If this conversion is not taking place efficiently, testosterone levels can become too high relative to estrogen. This hormonal imbalance is thought to affect normal hair growth and cause specific types of hair loss.

Q: What causes the hormonal imbalance that leads to female hair loss?

A: There are likely many causes. In some women it appears that genetic makeup plays a significant role in predisposing them to hair loss. Poor nutrition also might be a major contributor. The most common nutrition problem in pre-menopausal adult women is iron deficiency. Physicians studying female hair loss report that many cases improve with iron supplementation even when initial blood values for iron status are within normally acceptable ranges.

The link between iron deficiency and hair loss makes sense from a biochemical perspective. It turns out that iron is an essential player in the chemical reaction that converts testosterone into estrogen. So, if iron levels are low, then it makes sense that iron deficiency could lead to the hormonal conditions that cause hair thinning and hair loss.

Q: Are other nutrients related to female hair loss?

A: There are many types of hair loss that appear to be unrelated to nutrition. However, many nutrient deficiencies have the potential to affect hair growth. Hair is composed mostly of protein, and poor protein nutrition is known to adversely affect normal hair growth. Dr. Hugh Rushton at the University of Portsmouth has found that one component of protein called lysine can enhance the benefits of iron treatment in reducing hair loss.

A commonly used drug for treating hair loss, cyproterone acetate, appears to deplete vitamin B-12 levels. Rushton recommends evaluating B-12 status before using this treatment and combining a B-12 supplement with the drug when indicated.

Many other nutrients could potentially affect hair health. Consequently, a balanced diet that meets nutrient needs overall is critical for long-term maintenance of attractive hair.

Q: Can excessively high doses of any nutrients affect hair health?

A: Excessive vitamin A intake is known to cause hair loss along with many other serious problems such as bone loss and liver damage. High intake of other nutrients has the potential to affect hair, but other adverse effects would be of greater concern.

There are many potential causes for hair loss, but a balanced diet of wholesome foods can help prevent nutrient deficiencies from playing a role.

Joannie Dobbs, Ph.D., C.N.S., and Alan Titchenal, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.