Interactions with Malassezia yeasts

Malassezia yeasts are lipid-dependent organisms and prefer fatty acids with carbon chain lengths between 11 and 24 carbon atoms. Complex lipids composed of the C11-24 acids can provide essential nutrients for Malassezia, promoting their growth and colonization on the skin. As a result, most individuals are highly likely to experience a reaction from formulations that contain these ingredients.

As fermentation can alter a lipid's chemical composition, the influence of fermented lipids on Malassezia yeasts may differ from their unfermented counterparts. Although the specific microorganisms involved in the fermentation process can influence the resulting fatty acid profile, the general trend is towards the production and concentration of C11-24 acids.

Rating: Highly reactive for most individuals

Complex and fermented lipids are subject to the same factors that influence the severity of a reaction to C11-24 acids, along with some additional complexities. The fatty acid profile of a lipid can vary depending on its source, which can alter the availability of nutrients for Malassezia yeasts. The C11-24 acids present within a fermented lipid also vary based on the conditions of the fermentation process.

Despite these factors, complex and fermented lipids can offer abundant nutrients for Malassezia yeasts. As their presence significantly elevates the risk of an adverse skin response, we strongly recommend avoiding products containing these ingredients.

Matching requirements

Sezia checks for over 200 complex lipids containing C11-24 acids, including oils, butters, waxes, and milk. Sezia will match an ingredient's Latin name, as well as it common names and alternative spellings. It will also ignore filler words like "organic" or "cold pressed."

In the context of fermented lipids, Sezia will flag ingredients featuring the term "ferment" but only when coupled with specific keywords: butter, cera, fat, oil, olein, and wax.