What Is Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment?
Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment is a soybean-based ingredient created by letting two friendly bacteria, Lactobacillus and Streptococcus thermophilus, ferment soy extract. During fermentation the microbes break down large soy proteins and sugars into smaller, skin-loving molecules such as peptides, amino acids and natural moisturising factors. The finished liquid or powder is rich in these small compounds as well as vitamins from the soy itself.
Using fermented foods for beauty goes back centuries in East Asia where rice water and soy pastes were applied to keep skin soft. Modern labs picked up this idea in the early 2000s, isolating safe probiotic strains that could be used on skin and hair. By combining them with soy, chemists found they could boost softness and support the skin barrier without harsh chemicals.
To make the ingredient, clean soybeans are soaked, ground and filtered to create a watery extract. The extract is sterilised, cooled then inoculated with the two bacteria. After several hours of controlled warmth the mixture thickens slightly as the microbes do their work. It is then filtered, stabilised with mild preservatives and dried or kept as a liquid, ready to slot into cosmetic formulas.
You will most often see Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment in leave-on skin creams, hydrating masks, lightweight serums, soothing scalp treatments, anti-aging lotions and gentle hair conditioners where it helps add a silky feel.
Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment’s Cosmetic Benefits/Uses
Brands choose this ferment because it offers several helpful actions in one natural ingredient.
- Hair conditioning: The small peptides from soy coat strands making them smoother and easier to comb, which can reduce breakage and frizz
- Skin conditioning: The ferment delivers lightweight moisture, supports the skin’s protective barrier and can leave the surface feeling softer and more supple
- Emollient: It fills in tiny gaps on the skin or hair surface to create a soft, even feel without heaviness making formulas pleasant to apply
Who Can Use Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment
This ferment is gentle enough for most skin types. Dry and mature skin often enjoy its lightweight moisture while oily and combination skin appreciate that it softens without a greasy after-feel. Sensitive skin usually tolerates it well because the fermentation step lowers the chance of harsh proteins that can irritate, though anyone with a known soy allergy should avoid it.
The ingredient is suitable for vegans and vegetarians. It comes from soybeans and friendly bacteria, with no animal-derived materials used during production.
Current research shows no issues for women who are pregnant or breastfeeding when the ferment is used in a topical cosmetic formula. That said this is not medical advice and anyone expecting or nursing should run new products past a doctor just to be safe.
The ferment does not make skin more sensitive to the sun and can be used morning or night without extra sun precautions beyond normal SPF use.
Potential Side Effects/Adverse Reactions
Side effects and reactions to the topical use of Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment vary from person to person. The points below list potential but unlikely outcomes when the ingredient is used in a well-formulated product.
- Allergic response in individuals with soy allergy including redness, itching or swelling
- Mild irritation or stinging on very compromised or broken skin
- Temporary breakouts if a formula containing the ferment is too rich for acne-prone skin
- Scalp buildup or limp hair when overused in leave-on hair products
If you notice any discomfort or worsening symptoms while using the ingredient stop application and seek advice from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 / 5
The ferment is mostly water based and contains small, bio-available peptides that soak in quickly rather than sitting on top of the skin. It has no heavy oils or waxes that are known to clog pores which is why it earns a low score of 1. Minor comedogenic potential comes from the natural lipids present in soy but these are present in very low amounts after fermentation.
Because of this low rating the ingredient is generally suitable for people who are prone to acne or breakouts.
As with any cosmetic the final formula matters more than a single raw material, so a rich cream containing this ferment could still trigger congestion if other comedogenic ingredients are included.
Summary
Lactobacillus/Streptococcus Thermophilus/Soybean Extract Ferment conditions hair, conditions skin and acts as a lightweight emollient. Fermentation breaks large soy molecules into tiny peptides, amino acids and sugars that can slip into surface layers to smooth, hydrate and fill small gaps on skin or hair strands. These same molecules form a flexible film that leaves both skin and hair feeling soft and silky without heaviness.
The ingredient sits in the growing trend of probiotic inspired cosmetics but is still more of a niche choice compared to long-time staples like hyaluronic acid or shea butter. Brands that focus on gentle, microbiome friendly formulas are starting to spotlight it more often in serums, masks and scalp tonics.
Current data shows the ferment is very safe for topical use with low irritation and comedogenic risk. As with any new product it is wise to perform a small patch test first to confirm personal compatibility before full application.