Some suggested causes for dandruff:
Contrary to the old wives tales, dandruff isn't caused by too much shampooing or dry skin. It is triggered by overactive oil glands, food allergies, stress, excessive perspiration, or harsh shampoos. There is a common misconception that dandruff is caused by scalp skin being too dry. Hence some people avoid washing their hair, believing that the drying effect of shampoo will worsen their dandruff. Their scalp is probably not being cleansed enough; the scale is building up into larger, more noticeable flakes before it falls off the skin. Dandruff problems tend to occur more frequently in people with oily skin and hair.
Dandruff is caused by micro-organism called pityrosporum-ovle which are present in every body's scalp. Symptoms of dandruff get aggravated when exposed to dust, UV light, harsh chemical based shampoo, hair dyes etc., this results in increase in number of microbes which causes unhealthy residue over the scalp which leads to dandruff, which is the cause of unhealthy scalp results in unhealthy, lifeless hair and may result in excessive loss of hair too.
Contrary to popular notions, dandruff is usually a result of too much oiliness of the skin and scalp rather than dryness. While mild dandruff may be caused by overactive oil glands, recent evidence suggests that the more severe dandruff associated with seborrheic dermatitis may be caused by an overabundance of Pityrosporum ovale, a yeast-like organism found on healthy scalp in low numbers. With the increased scaling and oiliness of seborrheic dermatitis, these yeast organisms thrive and multiply, aggravating inflammation and scaling.
Seasonal changes, stress, and certain diseases seem to affect seborrheic dermatitis. The cold, dry air of fall and winter often triggers a flare-up. Emotional stress can worsen the condition as well. Skin cells that grow and die off too fast are the cause of dandruff, but doctors do not know why this happens. Some people with severe flaking have overactive sebaceous glands (whose task is to lubricate the skin with oils); others have an elevated level of the fungus Pityrosporum ovale, which is present in most people but to excess in dandruff sufferers. Other causative factors include family history, food allergies, excessive sweating, use of alkaline soaps, yeast infections, and stress. Even the season of the year can contribute to the problem: Cold, dry winters are notorious for bringing on dandruff or making it worse. If dandruff flakes are greasy and yellow, the probable cause is the skin condition known as seborrheic dermatitis; dry, thick lesions consisting of large, silvery scales may be traced to the less common psoriasis of the scalp. These forms of dandruff—as well as the run-of-the-mill variety—become a hazard only if you scratch to the point of causing breaks in the skin, which can place you at greater risk for infections, particularly from staph and strep bacteria.
(published with permission in writing from:http://members.surfeu.fi)
