Home remedies for cradle cap and dandruff may do more harm than good by feeding the little organisms that cause the condition, two doctors warned on Monday.

They said olive oil and other vegetable oil contain the very nutrients that feed the yeasts that cause dandruff and cradle cap. Mineral oil may be a better choice, they wrote in the Archives of Pediatrics & Adolescent Medicine.

Cradle cap and dandruff, known medically as seborrheic dermatitis, are both often caused by Malassezia yeasts.

“Treatment of this condition has supported a billion dollar market for over the-counter treatments,” Dr. Elaine Siegfried of St. Louis University and her colleague Dr. Erica Glenn, wrote. These include shampoos and other products.

Home remedies are all over the Internet – including a popular approach that recommends putting olive or vegetable oil on the head to loosen scales, brushing them off and then shampooing.

But the oils may feed Malassezia, which feeds on sebum, the oily stuff produced by pores and hair follicles.  And in fact, researchers who want to grow Malassezia yeast often grow it in olive oil. Sebum and vegetable oils are made up of both saturated and unsaturated fatty acids.  The yeast eats the saturated fatty acids. “Saturated fatty acids likely encourage Malassezia overgrowth and excess unsaturated fatty acids may induce inflammation and scaling,” Siegfried and Glenn wrote.

Mineral oil may be better, as it doesn’t contain digestible fatty acids.

“Based on the evidence currently available, it may be prudent to avoid organic oils, especially olive oil, when treating seborrheic dermatitis or other inflammatory skin diseases triggered by colonizing microflora,” Siegfried and Glenn concluded.

Related stories:

Scientists make dandruff gene map

The danger of detox diets

Home remedies for bad breath