Dandruff

Dandruff is a mild form of seborrheic dermatitis, and is characterized by a flaky, itchy scalp.^[1][2] Dandruff is common, affecting about 50% of the adult population worldwide, and is not caused by poor hygiene.^[3] It tends to start during puberty and occurs more frequently in males.^[4]

The main signs and symptoms of dandruff are:

• Skin flakes on the scalp, hair, eyebrows, beard, or shoulders
• Itchy scalp

Dandruff can occur completely on its own, but sometimes is a symptom of other illnesses like HIV/AIDS, neurological disorders (e.g., Parkinson’s disease, tardive dyskinesia, epilepsy), hepatitis C, chronic alcoholic pancreatitis, and some congenital disorders like Down syndrome.^[4]

Dandruff is commonly diagnosed by simply examining a patient’s scalp.^[1] It’s important to rule out other conditions that may initially appear similar, such as atopic dermatitis, tinea capitis, rosacea, and systemic lupus erythematous (SLE).^[4]

Dandruff is mainly treated with hair and scalp products, such as shampoos. These products typically contain antifungals (e.g., ketoconazole, pyrithione zinc, selenium sulfide), corticosteroids (e.g., hydrocortisone or fluocinolone), or compounds that slow skin turnover or flake accumulation (e.g., coal tar, salicylic acid). Many of these products are available over-the-counter, but some require prescriptions.^[1][5][4]

There is very little research on supplements for dandruff. However, vitamin A is known to reduce sebum production, so it may be beneficial for dandruff.^[6]

Although the consumption of micronutrients such as biotin and vitamin B is often recommended, there isn’t much evidence to show that they directly improve dandruff.^[7]

Some research suggests oral probiotics may improve dandruff.^[4]

The connection between diet and dandruff isn’t well described. However, intake of dietary fats, glucose, and acetate can all increase sebaceous gland activity, so a diet lower in these nutrients might help dandruff. Similarly, caloric restriction can reduce sebum production, and thus may ameliorate dandruff.

Shampoos containing tea tree oil have shown good effects against dandruff, but more research is required.^[8]

The causes of dandruff are not completely understood, although high levels of sebum secretion, the presence of the Malassezia genus of yeast (which feed on lipids present in sebum), and individual factors (e.g., skin barrier strength, immune response, genetics, neurological factors, and stress levels) are all thought to contribute to a person’s risk of having it.^[4] It’s worth noting that Malassezia is also found on many healthy people, which suggests host (individual) factors contribute strongly to the development of the condition.^[9]