Interactions with Malassezia yeasts

Malassezia yeasts can metabolize esters when derived from certain combinations of fatty acids, alcohols, and complex lipids. When exposed to Malassezia, esters undergo hydrolysis, allowing the yeasts to metabolize the resulting free fatty acids. While the yeasts cannot metabolize all esters, the nutrients they obtain from the ones they can exploit can promote the yeasts' growth and encourage their colonization on the skin.

Rating: Highly reactive under certain conditions

The severity of a reaction to a particular ester depends on a variety of factors. As different strains of yeasts have varying metabolic needs and preferences, some strains may more effectively metabolize certain esters. In addition, some ester structures may be more susceptible to enzymatic breakdown by the yeasts. Another factor is the concentration of fatty acids within the ester, which can affect its susceptibility to hydrolysis. Sezia is unable to account for these complexities. It will flag any ester known to feed any species in any concentration.

If a particular strain of Malassezia can metabolize a specific ester, individuals carrying that strain are highly likely react to formulations that include that ester. Consequently, we recommend avoiding products containing esters or, if necessary, exercising extreme caution when considering their use.

Matching requirements

Esters are typically composed of carboxylic acids and alcohols, though there are many variations. Sezia matches the following types:

• Basic esters, where the compound is prefixed with an alcohol and suffixed with an acid.
• Mono-, di-, and triesters.
• Esters formed from glycerol, including mono-, di-, and triglycerides.
• Esters formed from botanically derived lipids.
• Polysorbates and a variety of their alternative names.
• Esters formed from acid groups.
• Complex esters formed from combinations of the types above.