Midwest winters bring freshly fallen snow and, for some people, incessant scratching and white flakes on their shoulders – not from outside flurries, but from dandruff.

Dandruff, according to MayoClinic.com, is a “chronic scalp disorder, marked by itching and excessive flaking of the scalp.”

Kathy Cook, dermatologist for Skin Solutions, 500 Main St., said there are theories for the causes of dandruff, though there is not a single identified reason.

Cook said theories of what elicits dandruff include a zinc deficiency and a decrease in temperatures or humidity or, more likely, a yeast called malassezia. This yeast has been “potentially linked” to dandruff, but its culpability has not been verified.

Malassezia lives on the and can grow, “feeding on the oils secreted by your hair follicles and causing irritation that leads to increased cell turnover.”

Cook listed itching, flaking and scaling of white, dried skin as primary dandruff symptoms.

“If you scratch enough, it can get infected,” Cook warned.

Cook said the common belief that dandruff is related to a lack of washing or combing hair is a myth.

She said dandruff should not be ignored because preventive treatment is the key to minimizing it.

Cook also suggests using a mild over-the-counter shampoo containing active ingredients such as zinc and tar to combat dandruff. Dandruff shampoos are also available at retail stores.

“Shampoos are more gentle on the hair – compared to those of the past,” Cook said.

If you’re interested in a more natural approach, MayoClinic.com says tea tree oil shampoos can help ease dandruff symptoms.

Cook recommends leaving the shampoo on for five to ten minutes for it to be effective.

If your efforts to fight dandruff are ineffective, Cook said it is important to see a physician because stronger treatment may be needed.

MayoClinic.com said eating foods containing essential fatty acids, zinc and B vitamins could aid in decreasing dandruff.

Sally Barclay, clinician of food science and human nutrition, said sources of essential fatty acids include salmon, walnuts, yogurt and ground flaxseed oil.

After adding flaxseed to her diet, Barclay found her usually dry skin improved.

“Improving our diet can help benefit our health in many ways,” Barclay said.

Foods that contain a high amount of zinc include lamb, beef, shrimp, whole grains and dark greens.

Barclay said B vitamins are found in ordinary foods such as bananas, nuts, green vegetables and whole grains.

“[B vitamins] are essential for healthy skin and hair,” Barclay said.