α-Lipoic Acid (ALA) is a fatty acid that has physiological effects comparable to vitamins and minerals and is a vitamin-like substance (vitamin N). A deficiency in ALA may lead to a rare neurometabolic disease characterized by symptoms including seizures, muscle growth and control problems, feeding difficulties, and psychomotor delays. It is amphiphilic to low molecular weight sulfur-containing fatty acids and has strong antioxidant effects, and has been used for anti-aging, treatment of diabetic neuropathy, and as an antioxidant supplement.

Benefits

Lowers blood sugar, treats diabetes and related complications

α-lipoic acid has been shown to help lower blood sugar levels, with the main indications being diabetes and complications associated with impaired glucose metabolism, including neuropathy, especially in children and adolescents. Studies have shown that supplementation with α-lipoic acid appears to help improve insulin sensitivity and may also help prevent metabolic syndrome. In addition, ALA has also been used as a therapeutic agent for a variety of liver-related conditions, including alcohol-induced damage, mushroom poisoning, metal poisoning, and carbon tetrachloride poisoning. In many cases, supplementation with ALA can successfully treat these conditions.

Antioxidant

Alpha-lipoic acid is a natural compound with powerful antioxidant properties that help protect cells and tissues from oxidative stress. Preincubating cells with ALA enhances their ability to reduce extracellular ferrocyanide, recycle intracellular dehydroascorbic acid to ascorbic acid, reduce reactive oxygen species produced by the menaquinone redox cycle, and generate nitric oxide. These are thought to help treat conditions involving oxidative stress, such as diabetic neuropathy (neuropathy).

Helps with Weight Loss

Alpha-lipoic acid has potential weight loss benefits. It inhibits AMP-activated protein kinase (AMPK) activity, an enzyme that plays a role in appetite. Early studies in animals found that ALA promoted fat loss. A 2020 meta-analysis of placebo-controlled trials also found that ALA treatment significantly reduced BMI and body weight and may prevent obesity.

Helps with Anti-Aging and Skin Protection

Research suggests that topical treatment creams containing 5% alpha-lipoic acid can help reduce fine lines caused by sun exposure. Early research suggests that ALA may also help heal skin damage caused by cigarette smoke and promote wound healing.

Helps Lower Cholesterol

There is a threshold dose for lipoic acid for "anti-cholesterol properties": For people with high serum cholesterol levels, long-term treatment with 25 mg of lipoic acid twice daily did not change serum cholesterol levels, while 50 mg of lipoic acid once daily produced a modest decrease in serum cholesterol levels.

Side Effects

Alpha-lipoic acid supplements are well tolerated in most cases without serious side effects. Common side effects may include insomnia, fatigue, diarrhea, and rash. Common side effects when used as a medication include: nausea or low blood sugar levels (manifested as headache, hunger, weakness, sweating, confusion, irritability, dizziness, increased heart rate, or feeling nervous). Severe allergic reactions are rare.

References：

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[2] JUANITA BUSTAMANTE . α-Lipoic Acid in Liver Metabolism and Disease[J]. Free Radical Biology and Medicine, 1998, 24 6: Pages 1023-1039. DOI:10.1016/S0891-5849(97)00371-7.

[3] WRIGHT JONES . Uptake, recycling, and antioxidant actions of α-lipoic acid in endothelial cells[J]. Free Radical Biology and Medicine, 2002, 33 1: Pages 83-93. DOI:10.1016/S0891-5849(02)00862-6.

[4] YOSHIKI KUBOTA. Novel nanocapsule of α-lipoic acid reveals pigmentation improvement: α-Lipoic acid stimulates the proliferation and differentiation of keratinocyte in murine skin by topical application[J]. Experimental Dermatology, 2019, 28 S1: 55-63. DOI:10.1111/exd.13828.

[5] L. ANGELUCCI  E. M C. Anticholesterol Activity of α-Lipoic Acid[J]. Nature, 1958, 182 4632: 396-396. DOI:10.1038/182396b0.