Lipoic

Lipoic acid, commonly referred to as alpha-lipoic acid (ALA) or thioctic acid, is an organic compound with sulfur-containing rings that functions as a cofactor in energy metabolism. The naturally occurring form is the R-(+)-enantiomer, while synthetic preparations often contain a mixture of R and S enantiomers. Lipoic acid exists in two redox states: the oxidized form (lipoic acid) and the reduced form (dihydrolipoic acid, DHLA), which can interconvert as part of cellular redox cycling.

Biological role and distribution

Lipoic acid serves as a cofactor for several mitochondrial enzyme complexes that are essential for energy production, including pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase. These enzymes help oxidize substrates in carbohydrate and amino acid metabolism. Lipoic acid is both water- and fat-soluble, allowing it to operate in different cellular compartments. It is synthesized in mitochondria and also obtained from the diet, with sources including organ meats, red meat, spinach, broccoli, and yeast.

Antioxidant properties and interactions

In the body, lipoic acid and dihydrolipoic acid participate in redox reactions that can help scavenge reactive oxygen species. They also regenerate other antioxidants, such as vitamin C, vitamin E, and glutathione, contributing to the cellular antioxidant network. Additionally, lipoic acid can chelate metal ions in some contexts, which may influence oxidative processes.

Clinical use and research

Lipoic acid is used as a dietary supplement and has been investigated for conditions such as peripheral neuropathy (particularly in diabetes) and certain metabolic disorders. Evidence for efficacy varies by condition, and benefits are not universally demonstrated. It is generally well tolerated but can cause mild gastrointestinal symptoms in some individuals and may interact with glucose-lowering medications.

Safety and regulation

As a supplement, lipoic acid is subject to dietary supplement regulation and quality varies by product. People considering its use should consult healthcare providers, especially those with diabetes or other metabolic conditions.