Malassezia-Feeding ingredients

Interactions with Malassezia yeasts

Malassezia are natural members of our skin's microbiome. They are lipid-dependent organisms and prefer fatty acids with carbon chain lengths between 11 and 24 carbon atoms. Sebum, the skins natural oil, is the yeast's primary source for fatty acids in this range.

Products containing C11-24 acids can provide excess nutrients for the yeasts to exploit, 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.

Rating: Highly reactive for most individuals

Many factors can contribute to the severity of a reaction to one of the C11-24 acids. The chemical composition of an acid varies depending on its source, which alters the availability of nutrients for Malassezia yeasts. In addition, the acid's concentration within a product or the presence of other ingredients can affect its influence.

Despite these factors, the C11-24 acids remain a direct source of 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 the names of the C11-24 acids, in common or IUPAC form. It also checks for acid groups that include them.

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.

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.

Interactions with Malassezia yeasts

Galactomyces is a type of yeast commonly used in cosmetics that has potential to influence skin conditions associated with Malassezia yeasts. Galactomyces is known to stimulate the Aryl Hydrocarbon Receptor (AhR), a protein that plays a role in how our skin reacts to certain substances. As studies have implicated Malassezia yeasts in diseased skin with excess AhR activity, individuals suffering from Malassezia-related diseases may benefit from avoiding additional AhR stimulants as a precautionary measure.

Rating: Highly reactive under certain conditions

Reactivity to products containing Galactomyces may depend on the condition of your skin and the duration of the product's use. While there is some uncertainty due to multiple influencing factors, there is a significant chance that Galactomyces will aggravate conditions associated with Malassezia yeasts. We strongly recommend avoiding products containing Galactomyces.

Matching requirements

Sezia will match any ingredient with the term "Galactomyces."

Interactions with Malassezia yeasts

This category includes non-lipid ferments and strains of yeast that are not directly implicated in conditions involving Malassezia yeasts. Skincare products containing these ingredients can influence the skin's microbial community. However, their impact on Malassezia related skin conditions is often unclear. They can potentially prevent Malassezia growth by enhancing skin biodiversity and balancing the natural microbiome. Yet due to the diverse range of microbes involved, they can sometimes trigger an immune response that results in skin irritation or worsens existing conditions.

Rating: Reactivity depends on skin tolerance

Those with sensitive skin, compromised skin barriers, allergies, or specific dermatological conditions may be more prone to reactions to these ingredients. Some people may find that their skin tolerates them well and even benefits from them, while others may experience a reaction. Reactivity may also depend on the product formulation, the duration of it's use, or the presence of other ingredients.

For individuals with sensitive skin, we recommend avoiding products with these ingredients. But if your skin tolerates fermented or yeast-based ingredients well, you may consider using them with caution.

Matching requirements

Sezia checks for ingredients that contain the following keywords:

• Ferment(s)
• Ferment filtrate
• Ferment extract
• Yeast
• Faex
• Saccharomyces