Alpha lipoic acid (ALA) is an endogenous cofactor found in cells that can also be obtained in the diet. It is sometimes referred to as a “universal antioxidant” because it is both water- and fat-soluble and can neutralize reactive oxygen species ⁽²⁶⁾. It is marketed as a dietary supplement for this reason, and is also used as adjuvant therapy for neuropathy and to improve glycemic control. Preclinical studies show that ALA plays a crucial role in energy production, and exerts antioxidant and apoptotic effects ^{(1) (2) (3)}.

Studies on ALA in humans have been conducted across various populations. Preliminary data suggest long-term supplementation may help preserve walking ability in patients with secondary progressive multiple sclerosis, especially those with less disability at baseline ⁽²⁷⁾. Studies of intravenous and oral forms suggest improved insulin sensitivity, vasodilation, and neuropathy symptoms in diabetic patients ^{(5) (6) (7) (21) (28)}, although earlier studies to determine its role in reversing neuropathies ^(8) (9) and liver disease ^(10) (11) produced mixed results. In women with gestational diabetes, oral ALA may improve liver function and glucose metabolism ⁽²⁹⁾. Meta-analyses also suggest ALA supplementation may reduce inflammatory mediators such as CRP, IL-6, TNF-α, and improve some glucose and lipid parameters ^{(30) (31) (32) (33) (34)}, but confirming studies are needed.

In other preliminary studies, ALA induced mild weight loss and waist circumference reduction ⁽²³⁾ in overweight or obese subjects. It also improved wound healing and scarring in women undergoing cesarean section ⁽³⁵⁾, and reduced postsurgical pain after carpal tunnel decompression ⁽²⁴⁾. In patients with atrial fibrillation, it reduced serum markers of inflammation, but not AF recurrence after ablative treatment ⁽²⁵⁾.

Although current data suggest protective effects of antioxidants against Alzheimer’s disease, such effects were not found with a combination of coenzyme Q, vitamin C, vitamin E, and ALA ⁽²⁰⁾. But topical application with creams containing ALA may help prevent photoaging of facial skin ⁽¹²⁾.

High doses of ALA can cause hypoglycemic symptoms ⁽⁴⁾, as well as other serious conditions. In addition, because of its antioxidant effects, ALA may antagonize the effects of chemotherapy and radiation therapy.