Phytosterols

Phytosterols are plant-derived sterols (you can think of them as the plant world's version of cholesterol). In cosmetics, this ingredient is usually sourced from soybean, rice bran, shea, sunflower, and other seed oils.

The main actors in this group are β-sitosterol, campesterol, and stigmasterol (the CIR covers 27 phytosterols).

They work by fitting perfectly into your stratum corneum's lipid matrix since they're structurally similar to cholesterol. Here, they reinforce your skin's barrier.

One small in vivo human study showed topical soybean phytosterols sped up barrier recovery within three days on tape-stripped skin.

Broader research credits them with:

• Reducing transepidermal water loss
• Calming inflammation by downregulating inflammation signals
• Supporting elasticity

Formulation use typically sit under 5%.

Testing in soy-allergic subjects found no sensitization signals, but be sure to patch test if you are unsure or have existing allergies.