PARIS, July 1 -- Data presented today by The Procter & Gamble Company research scientists at the 20th World Congress of Dermatology (WCD) suggests that dandruff does not result from an overabundance of Malassezia furfur (M. furfur) fungus as previously thought. Rather, common dandruff, the scalp condition affecting more than 50 percent of Caucasians and 80 percent of people of African descent, is caused by the lipid waste of two other Malassezia species, M. restricta and M. globosa.

In a research study conducted by Thomas Dawson, Jr., Ph.D., senior scientist in beauty care technology for P&G, titled, "Fast, Non-invasive Method for Molecular Detection and Speciation of Malassezia on Human Skin, and Application to Dandruff Microbiology," scalp samples from 70 people with dandruff showed the presence of Malassezia species. But in these cases, M. restricta was present in 70 percent and M. globosa in 45 percent. M. furfur was not detected in any of the samples.

Malassezia is a lipophilic fungal genus, members of which are part of the normal human scalp flora. M. restricta and M. globosa feed on lipids secreted from the hair follicles. The partially digested lipids that linger on the skin cause the familiar irritation of the scalp that leads to dandruff.

"We have been studying dandruff and other scalp conditions for many years, concentrating on the specific organism that causes the disorder," said Dr. Dawson. "We expect these data will provide insight into the development of new approaches to dandruff treatment."

"These new data on the real cause of dandruff are a major step forward in understanding dandruff that will be important to the dermatology community," said Boni E. Elewski, MD, Professor of Dermatology at the University of Alabama, Birmingham, and internationally-recognized authority on cutaneous fungal infections and dandruff. "This research will allow development of more effective anti-dandruff treatments that will not only treat the condition, but may also help prevent it from occurring."

Dr. Dawson's findings also apply to seborrheic dermatitis, a severe form of dandruff that affects up to 10 percent of Caucasians and leads to heavy flaking, severe itchiness, redness and inflammation. Earlier work by this team of P&G scientists has shown that excess lipids are correlated to dandruff and seborrheic dermatitis, and this study showed that reducing the amount of sebum by more frequent washing improved the clinical signs of seborrheic dermatitis. This also lends support to the theory that sebum has a positive effect on the growth of fungus.

Additional Research

Dr. Dawson noted that P&G will conduct detailed quantitative studies to better define the role of other Malassezia fungi, as well as the role of individual sensitivity to M. globosa and M. restricta.

"P&G is committed to researching and understanding the science behind skin conditions like dandruff, so we can continue to provide medical professionals and consumers with the most effective treatments," said Eric Armstrong, Vice President of Research & Development for the company's Global Hair Care Division. "In particular, P&G will seek to understand, identify, and characterize the role of individual lipids associated with dandruff and seborrheic dermatitis, in order to continue to develop the highest efficacy anti-dandruff products. In addition, P&G scientists will explore the reasons why some patients react to the presence of Malassezia, while others do not."

Malassezia and Dandruff

In years past, the scientific community disagreed about the role of Malassezia in dandruff. Some scientists argued that an increase in cell turnover on the scalp was the main cause of dandruff, and microorganisms, such as Malassezia, only reflected the underlying abnormality of the skin.

In the 1970s and 80s, with scientific studies demonstrating the effectiveness of specific anti-fungal agents in improving chronic scalp conditions, scientists proved a correlation between Malassezia in both dandruff and seborrheic dermatitis. Scientists assumed that M. furfur was the cause.

Only recently have scientific studies supported the relationship between Malassezia and lipids in connection with dandruff. Past studies show Malassezia's involvement in a number of pathologies related to alterations of the skin's surface lipids. Results from this study suggest that only two of nine Malassezia species are present on the scalp that could digest the naturally occurring lipids. In addition to showing the connection between dandruff and M. restricta and M. globosa, this research also shows that to remain viable, Malassezia uses its enzymes to break down non-irritating triglycerides (lipids) into irritating free fatty acids.