Alpha-lipoic acid

About Alpha-lipoic acid

A sulphur-containing compound made in mitochondria as a cofactor for several dehydrogenase enzymes. Supplements are usually the synthetic racemic mixture of R and S forms, both soluble in water and fat.

Alpha-lipoic acid has the most substantial clinical record of anything in the general antioxidant category, and it comes from an unusual place: German trials of intravenous and oral thioctic acid for the symptoms of diabetic peripheral neuropathy, running from the 1990s onward. Those trials reported reductions in neuropathic symptom scores at 600 mg daily, though the largest and longest of them missed its primary endpoint. Outside neuropathy the picture thins quickly — meta-analyses of metabolic markers and body weight show small, inconsistent effects. The compound also has a specific and genuinely important safety signal that is almost never mentioned on labels.

Sold as

Capsule, Tablet, Enteric-coated capsule, Intravenous (clinical use in some countries)

Standardised to

Milligrams; racemic unless a product specifies R-lipoic acid — a product without this marker may not resemble what was studied.

Also known as

ALA, Thioctic acid, Lipoic acid, Racemic lipoic acid

Regulation: A dietary supplement in the US with no pre-market efficacy review. Available as a licensed medicine for diabetic neuropathy in Germany and several other countries, which is where most of the trial evidence comes from.

What the research used

The amounts, forms and durations published trials of Alpha-lipoic acid actually administered.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.