Ferments and probiotics, explained
Galactomyces, bifida, fermented black rice: fermentation is one of Korean skincare’s signatures. Here’s what it actually does.
Research growing
What it is
Fermented ingredients are made by letting yeast or bacteria break down plants such as rice, soybeans or ginseng. Galactomyces ferment filtrate comes from a yeast used in rice-wine making, and bifida ferment lysate comes from bacteria. “Probiotic-derived” ingredients in skincare are not live bacteria; they’re extracts or lysates made from them.
Fermentation can break ingredients into smaller pieces and create new ones, such as amino acids and antioxidants, which brands say makes them gentler and better absorbed.
What the research shows
In a placebo-controlled study of 66 women with reactive skin, a cream with a bifidobacterium lysate reduced skin sensitivity and improved barrier function over two months.
Guéniche and colleagues, Experimental Dermatology, 2010 [1]
Lab studies suggest galactomyces and other ferments have antioxidant and soothing effects, but there are very few independent human trials of the exact ingredients used in K-beauty.
Seoul River summary of published research
The idea is sensible and early results are encouraging, but most claims come from brands rather than independent trials.
Who it suits
Ferments are usually gentle and suit dull, dry or reactive skin well. They’re a nice extra rather than an essential. If you have a yeast-related skin condition or very reactive skin, patch test first.
How to use it after 40
- Use fermented essences or toners after cleansing, before serums.
- They layer well with almost everything.
- Give any new product four to eight weeks.
Sources
This page is general information, not medical advice. Last updated 4 November 2026.
Products with ferments
The cheapest price we found at trusted UK shops. Tap a product to compare every shop.
- Compare prices for Haruharu Wonder Black Rice Moisture 5.5 Soft Cleansing Gelfrom £14.00
- Compare prices for Biodance Bio-Collagen Real Deep Maskfrom £14.90
- Compare prices for Haruharu Wonder Black Rice 10 Hyaluronic Creamfrom £15.00
- Compare prices for Haruharu Wonder Black Rice Bakuchiol Eye Creamfrom £15.00
- Compare prices for Beauty of Joseon Relief Sun: Rice + Probiotics SPF50+from £15.50
- Compare prices for Haruharu Wonder Black Rice Hyaluronic Tonerfrom £16.00
- Compare prices for Numbuzin No.3 Super Glowing Essence Tonerfrom £17.00
- Compare prices for Haruharu Wonder Black Rice 5 Ceramide Barrier Moisturising Creamfrom £19.00