The latest study into scaly scalps has found that nurturing particular bacteria on the skin could keep the white flakes at bay.

Researchers in Shanghai took on the dandruff problem with an unprecedented investigation into flaky scalps and the ecosystem of microbes that set up home on the human head, feeding on the lavish menu of dead skin and oily secretions called sebum.

Menghui Zhang at Shanghai Jiao Tong University invited 59 people aged 18 to 60 years old into the lab and gathered dandruff from eight different areas on their heads. All had washed their hair two days before turning up at the centre.

Zhang separated the volunteers into “healthy” and dandruff groups, depending on the amount of visible skin flakes in their hair. He then looked to see how the populations of scalp bacteria and fungi differed between the two groups, and with individual’s sex, age and physiology.

The researchers found that sebum secretions rose through the teenage years, peaked at 15 to 35 years old, and then declined as people got older. Meanwhile, dandruff became worse as people aged, with the over 40s having more severe dandruff than the younger participants. Writing in the journal Scientific Reports, the authors note: “Sebum is an important food source for the growth of fungi and bacteria.”

In previous work, scientists had identified a group of fungi called Malassezia as potential culprits in causing dandruff. The yeast eat fatty substances in sebum and produce oleic acid, which irritates the skin and may cause the scalp to flake. But in the latest study, Zhang found Malassezia fungi on the heads of people without dandruff, suggesting flaky skin might be made in other ways.