Dandruff (or dry flaky scalp) is an itchy, annoying and persistent skin disorder of the scalp. Dandruff appears to be on the rise in the United States. There are many theories about what actually causes dandruff and a variety of treatments to control it. Dandruff can happen at any age (called cradle cap in newborns and infants) but is most commonly found in people above the age of 12.
Suggested internal causes include hormonal imbalance, excessive perspiration, excessive consumption of sugar, fat, or starch, emotional stress, lack of rest, heredity pre-disposition, poor hygiene, allergy (dairy products, chocolate, nuts and shellfish), and poor nutrition.
Possible external causes include infrequent shampooing of the hair or inadequate rinsing, cold weather and dry indoor heating, improper use of hair-coloring products, hairsprays and gels or excessive use of electric hair curlers, and infection with a fungus called Pityrosporum ovale. P. ovale lives on our bodies and scalp all the time, usually without causing a problem. Unfortunately, for some people, it can increase in numbers, leading to dandruff.
Dandruff has been blamed on a multiplicity of causes, but a recent discovery (Nov 2007) has uncovered the cause - a yeast-like fungus, Malassezia globosa, which lives on your scalp, feeding on skin oils.
Dandruff is shedded skin; dandruff sufferers shed skin much more rapidly than other people. This happens because the fungus uses enzymes called lipases to metabolize the oils, which creates a by-product called oleic acid. The acid penetrates your skin and triggers skin cell shedding.
A team of researchers for Procter & Gamble (manufacturers of Head & Shoulders anti-dandruff shampoo) has sequenced the DNA of the fungus and analyzed the lipases it produces. They hope these investigations will eventually lead to new treatments for dandruff.
Dandruff can be seasonal. It is most severe during the winter and mildest during the summer. Scaling can occur anywhere on the scalp, in the hair, on the eyebrows, the beard and can spread to the neck and shoulders. Dandruff is often known as "dry scalp", but people with oily scalps tend to suffer the most.
As of 2007, the most common dandruff treatments are shampoos containing coal-tar, pyrithione zinc, salicylic acid, selenium sulfide, and sulfur. A key point to remember is to select the mildest shampoo possible. Although detergent based shampoos will clean the hair and scalp well, they often cause drying which will make the flaking worse.