Lactobacillus/Soybean Ferment Extract

Lactobacillus/Soybean Ferment Extract is the result of fermenting soybeans with the Lactobacillus bacteria. It mainly acts as a skin conditioning agent in a formula, and the interesting part is what fermentation does to the soy.

Fermenting soy:

1. Breaks down the "glycoside" isoflavones in soybean down to their "aglycone" forms. These forms can absorb into skin more easily than the unfermented versions.
2. Chops large soy proteins into smaller peptides and amino acids (also lowering the allergy risk that raw soy protein can carry).

The isoflavones are the workhorses behind the common claims; lab and animal studies show they mop up free radicals, help protect skin cells from UVB damage, and nudge fibroblasts to make more collagen while slowing the enzymes that break collagen down.

One controlled clinical study using an isoflavone cream reported softer wrinkles and better skin texture over time. A topical fermented soy extract also improved hydration and elasticity in an animal aging model.

The big caveat is that most of this evidence comes from soy isoflavones and related fermented soy extracts rather than this exact INCI. Some of the strongest data also comes from oral studies.

So it's best to think of this ingredient as a gentle, antioxidant-leaning conditioning agent rather than a proven wrinkle eraser.

At this time, there's no published concentration levels for this specific ferment but it usually shows up at modest levels in real products (~1% or less).

One last thing for people with soy allergies: it's always worth patch testing this ingredient despite the lowered allergy risk.