Isoleucine God Humectant Fugt Isoleucine at a glance An essential amino acid that provides hydrating benefits Plays a role in maintaining collagen and elastin (when consumed) Works with other amino acids to maintain skin’s barrier May be animal-derived or synthetic Isoleucine description Isoleucine is an essential amino acid that has slight humectant (water-binding) properties for skin. It’s considered essential since the human body cannot make isoleucine and so it must be obtained via foods or supplements. Isoleucine works with other amino acids to help maintain skin’s barrier and initiate surface repair so skin looks healthier. It is often combined with several amino acids for enhanced benefits. This amino acid may be animal-derived or synthetic (Paula’s Choice uses the latter) and its typical concentration in skin care ranges from 0.0003–0.002%, as very little of this ingredient is needed in order for skin to benefit. Related ingredients: Amino Acids