Alpha-lipoic acid

Also known as ALA, lipoic acid, R-lipoic acid, alpha lipoic.

Last reviewed October 9, 2026 · Jump to references

What is Alpha-lipoic acid?

In plain words

Alpha-lipoic acid is a substance the body makes to help turn food into energy. Cells also convert it into a form that takes part in reactions involved in protecting cells from damage. Researchers study it for diabetes-related nerve symptoms and blood sugar control. Evidence for benefits varies, and supplements can cause stomach upset or lower blood sugar.

Technical definition

Alpha-lipoic acid (ALA) is an endogenous organosulfur compound derived from octanoic acid, with a five-membered disulfide ring; its naturally occurring R-enantiomer functions as a protein-bound cofactor for mitochondrial enzyme complexes, including pyruvate dehydrogenase. Rather than acting through a single receptor, it supports oxidative energy metabolism, while free ALA and its reduced form, dihydrolipoic acid, participate in redox reactions. It is marketed as a dietary supplement in the United States and is used as a medicine for diabetic neuropathy in some countries.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.