How Diet Affects Hair and Scalp Health

Baldness and dandruff are among the most pervasive hair and scalp problems. Below you’ll find information on both issues, along with suggestions for specific foods to incorporate into your diet: Hair is composed of the protein keratin. Because hair is inert material, shampoos and rinses enriched with protein or other nutrients cannot affect hair growth or make hair “healthier.”

About hair loss. Hair loss may be either the result of illness or a normal genetic response to testosterone, the male sex hormone. A healthy human head has from 80,000 to 150,000 hairs, each of which passes through three phases of growth independently of all the others. At any time, 90 percent of the hairs are in the growing stage (anagen), which lasts anywhere from 1 to 5 years. Growth is followed by a resting phase (telogen); this ends after a few months, after which the hair is shed (catagen) to allow new growth. A daily loss of 50 to 200 hairs is a normal part of the cycle.

Although baldness is mediated by hormonal factors, it tends to run in families; your risk may be deduced from the number of bald males among members of both parents’ families. Abnormal hair loss may be precipitated by metabolic disorders (including diabetes, thyroid disease, and crash diets); damage to hair shafts caused by harsh treatments; stress brought on by illness; hormonal changes of pregnancy; medical treatment, including cancer chemotherapy; and very severe scalp disorders.

Nutritional causes may be a grossly excessive intake of vitamin A or a deficiency of iron, biotin, zinc, or protein. Such deficiencies are rare, although an excessive intake of raw egg whites can lead to a depletion of biotin.

Treatments. The only medicines for baldness are minoxidil (Rogaine), a topical medicine, and finasteride (Propecia), an oral prescription drug. Hair loss due to stress or drug treatment is generally temporary. Hair that falls out during a crash diet soon regrows once nutrition returns to normal. Hair lost in patches usually grows back without treatment, but in some instances, corticosteroid injections may be needed.

About dandruff. Dandruff — excessive scaling of the scalp — affects more than 50 percent of the population. It may be due to stress or a chronic or recurrent skin disorder, such as seborrheic dermatitis, but the most likely cause is infection by Pytyrosporum ovale fungus. This fungus is found naturally on the scalp but some people are more affected by it than others. It feeds on the skin’s natural oils and causes irritation and shedding of dead skin. Many people shed flakes of dandruff, especially in winter, when the scalp may be dry. But some people have a hereditary tendency to develop skin problems that are triggered by a sensitivity to specific foods. Because the offending food varies from one person to the next, the only reasonable advice is to avoid foods that seem to make dandruff worse.

Treatments. Some cases of dandruff may respond to flaxseed oil, which seems to help itchy skin conditions such as psoriasis and eczema. Take 1 to 2 teaspoons a day. You’ll need to wait several weeks or months to see an effect.

To control mild dandruff, doctors usually recommend shampooing daily until the dandruff is under control, followed by twice weekly for maintenance. Dandruff shampoos contain zinc pyrithione, tar, or selenium sulfide, all of which work as exfoliants to hasten the shedding of the dead cell layer from the scalp. If these do not work well, shampoos that contain the antifungal medication ketoconazole can be tried.

Dietary factors affecting hair and scalp. Scientific analysis of hair can confirm the presence of certain toxic elements — even years later. (Hair analysis was used 150 years after Napoleon’s death to confirm that he suffered chronic arsenic poisoning.) Though providing such critical information to researchers, hair analysis cannot determine nutritional deficiencies — any such claim is worthless. Nutrients that contribute to hair and scalp health include niacin, biotin, zinc, and vitamins A, B₆, and C. A varied diet based on the basic food groups should provide ample amounts of these nutrients, although certain foods may actually cause problems. In some instances, dandruff may be improved when certain foods (hot liquids, heavily spiced foods, and alcohol) are eliminated. For hair and scalp health, the following is recommended:

• Fruits and vegetables
• Whole grains
• Lean meat, fish, and poultry
• Low-fat dairy products

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