Thioctic Acid

goodie
Also-called-like-this: Alpha-Lipoic Acid
What-it-does: antioxidant

Alpha-Lipoic Acid (ALA) is a great antioxidant that's also part of the body's natural antioxidant system. It's soluble both in water-rich and lipid-rich environments so it's versatile and can interact with many types of evil oxidants as well as other nice antioxidants. 

ALA seems to be a great choice for topical use as studies show it can penetrate the skin rapidly where it's converted to DHLA (dihydrolipoic acid), an even more potent antioxidant molecule.  A nicely designed (we mean double-blind, placebo-controlled) 12-week study from 2003 confirmed that 5% ALA cream can decrease skin roughness and improve general signs of photoaging statistically significantly.  A slight catch, though, is that burning and warmth in the skin was quite a common side effect, especially in the first 4 weeks. 

All in all, ALA is definitely a research-proven, great antioxidant but if your skin is sensitive higher concentrations might not be for you.