Alpha-Lipoic Acid: What It Is, How It Works, and What Evidence Shows Today

Alpha-lipoic acid (ALA) is a mitochondrial cofactor and antioxidant that helps regenerate glutathione and other antioxidants. Clinical trials support its use for diabetic neuropathy at typical supplemental doses (300-600 mg/day). Other claimed benefits - for cardiovascular disease, cataracts, or liver detox - have mixed or limited evidence. ALA can cause GI side effects and may interact with diabetes medications.

What alpha-lipoic acid (ALA) is

Alpha-lipoic acid (ALA) is a small antioxidant molecule that humans make in small amounts and also obtain from food. In cells it functions as a cofactor for mitochondrial enzyme complexes (for example, pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase) that help generate cellular energy.

How ALA works

ALA is both water- and fat-soluble, which lets it act across different cell compartments. It participates in redox reactions, supports regeneration of endogenous antioxidants (glutathione, vitamin C, and vitamin E), and contributes to cellular energy metabolism. Supplements usually contain a racemic mix of R- and S-enantiomers; the R-form is the naturally occurring isomer and is considered the biologically active form.

Dietary sources and supplement forms

Food sources include organ meats and muscle meat (red meat), spinach, broccoli, and yeast, but amounts in food are small. Most therapeutic uses rely on oral supplements. Typical clinical trials use 300-600 mg daily; formulations differ (racemic ALA, R-ALA, sustained-release). Absorption and bioavailability vary by formulation.

What clinical evidence supports?

• Diabetic neuropathy: Multiple randomized trials and clinical experience support that oral ALA (commonly 600 mg/day) can reduce symptoms of diabetic peripheral neuropathy, such as pain and numbness.

• Blood sugar: ALA can modestly improve insulin sensitivity and lower blood glucose in some studies, but it should not replace prescribed diabetes medications.

• Other uses: Research has explored ALA for cognitive aging, liver conditions, cardiovascular risk factors, and eye health (cataracts, retinal aging). Evidence beyond neuropathy is mixed or preliminary; benefits for "opening artery blockages" or reliably preventing cataracts are not established in high-quality clinical trials.

Safety and interactions

Common side effects are gastrointestinal (nausea, upset stomach) and occasional skin rash. Because ALA can enhance insulin sensitivity, it may increase the risk of low blood sugar when combined with antidiabetic drugs - monitor glucose and consult a clinician if you have diabetes.

There are rare case reports linking ALA to autoimmune hypoglycemia (insulin autoimmune syndrome) in certain populations; clinicians should be aware of this possibility. ¹

Pregnancy and breastfeeding: safety data are limited; avoid or discuss with a clinician.

Practical takeaways

ALA is a biologically active antioxidant and mitochondrial cofactor with the best clinical support for alleviating symptoms of diabetic neuropathy at doses commonly used in trials (300-600 mg/day). Food contains only small amounts, so therapeutic effects typically require supplements. Discuss dosing and drug interactions with your clinician before starting ALA.

1. Verify case reports and prevalence linking alpha-lipoic acid to insulin autoimmune syndrome (Hirata disease) and identify any population risk factors.
2. Confirm current high-quality evidence status regarding ALA effects on cardiovascular plaque regression, cataract prevention, and liver disease treatment.