Living Proof Restore Repair Leave-In

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

This ingredient may not be fungal acne safe.

Surfactants also help your cleansers remove pollutants more easily from the skin.

A 2023 review noted that probiotic fermentation ingredients like this one can enhance antioxidant capacity, reduce UV-induced oxidative damage, and support barrier function.

One clinical study from the same year showed a Lactobacillus ferment lysate significantly reduced transepidermal water loss and improved skin hydration.

Another review highlighted that topical Lactobacillus-based preparations can improve ceramide levels in the stratum corneum, support barrier integrity, and even help reduce S. aureus colonization in atopic dermatitis.

Why is this so cool?

Basically, your skin's outer layer works as a brick wall; skin cells are bricks and ceramides are the mortar holding it together. Moisture escapes, irritants get in, and your skin gets dry and reactive when ceramide levels drop. On top of that, "bad" skin bacteria S. aureus loves to move in when your barrier is weak to make inflammation and irritation worse.

So Lactobacillus ferment is basically patching the wall and evicting the troublemaker when it boosts ceramide production and help keep S. aureus in check.

On top of all this, it also acts as a mild antimicrobial preservative booster.

Just so you know, most studies focus on specific strains or the lysate form rather than this generic "Lactobacillus Ferment", so results can vary.

Though it's a promising ingredient, it doesn't have decades of robust clinical data behind it just yet.

Lactobacillus Ferment is generally considered safe for fungal-acne prone skin. The key thing to understand is that it comes from bacteria, not yeast or fungus.

Yeast-derived ferments (like galactomyces) have been shown to activate a protein that's linked to Malassezia-related skin issues whereas lactobacillus doesn't have that problem.

Its byproducts also don't contain the types of fatty acids (C11-24 chain lengths) that Malassezia feeds on.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Overall, this ingredient is well tolerated. However, those with very oily or clog-prone skin might prefer it in lighter formulations or lower concentrations.

Due to its fatty acid content, this ingredient may not be Malassezia folliculitis, or fungal acne, safe.

Please note: Fungal acne is not caused by pore clogging. It is caused by an overgrowth of the Malassezia yeast on the skin. This yeast feeds on certain fatty acids.

In testing, this ingredient was nontoxic in acute oral studies and not a skin irritant or sensitizer.

You might hear concerns about 1,4-dioxane as a byproduct of ethoxylation; this is well-known in the industry and is controlled through purification steps before the ingredient is blended into finished products.

Because it is not a free-fatty acid or alcohol, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).

This ingredient can also be found in pill medicines to help our bodies digest other ingredients.

This ingredient may not be Malassezia folliculitis, or fungal-acne safe.

This ingredient is not irritating or sensitizing. Recent research also suggests it may have skin-brightening effects through tyrosinase inhibition.

For instance, Habanolide is a proprietary trade name for a specific aroma chemical. When used as a fragrance ingredient in cosmetics, most aroma chemicals fall under the broad labeling category of “FRAGRANCE” or “PARFUM” according to EU and US regulations.

The term 'parfum' or 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term.

For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance by INCI standards.

One example is Calendula flower extract. Calendula is an essential oil that still imparts a scent or 'fragrance'.

Depending on the blend, the ingredients in the mixture can cause allergies and sensitivities on the skin. Some ingredients that are known EU allergens include linalool and citronellol.

Parfum can also be used to mask or cover an unpleasant scent.

The bottom line is: not all fragrances/parfum/ingredients are created equally. If you are worried about fragrances, we recommend taking a closer look at an ingredient. And of course, we always recommend speaking with a professional.

Limonene acts as an antioxidant, meaning it helps neutralize free radicals.

When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.

The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.

Hexyl Cinnamal is not water soluble but is soluble in oils.

This ingredient has a scent that is floral, spicy tropical, and citrus-like.

Citronellol is a modified terpene. Terpenes are unsaturated hydrocarbons found in plants. They make up the primary part of essential oils.

Citronellol is not able to be absorbed into deeper layers of the skin. It has low permeability,

Citronellol is also a natural insect repellent.

You should know this ingredient is a known EU fragrance allergen.

Animal studies classifies this ingredient as a weak-to-moderate skin sensitizer and clinical patch testing on eczema patients confirmed it to be both a contact allergen and irritant.

The term 'citral' is a collective term for two geometric isomers: geranial/Citral A and neral/Citral B.

The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.