Summary
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What is alpha-lipoic acid?
Alpha-lipoic acid (or lipoic acid) assists in converting glucose into energy (see What It Is). A healthy body naturally produces enough alpha-lipoic acid but supplementation may help in certain situations. -
What does alpha-lipoic acid do?
Alpha-lipoic acid supplements may modestly improve insulin sensitivity and blood sugar control, as well as reduce symptoms of peripheral neuropathy in people with type 2 diabetes. It may also modestly increase weight and fat loss when combined with a low-calorie diet (see What It Does). -
Which form of alpha-lipoic acid is best?
Supplements contain synthetic versions of the naturally occurring form of alpha-lipoic acid (the R-isomer) or, more commonly, a mixture of the R- and S-isomers. The R-isomer only isomer shown to be active of the two isomers. However, only mixed forms have been studied for efficacy and side-effects in clinical trials and are generally much less expensive than R-isomer-only products (see What to Consider When Buying). -
What's the right dose of alpha-lipoic acid?
The typical dose used in treating diabetes, peripheral neuropathy associated with diabetes, and cardiac autonomic neuropathy is 200 to 400 mg, taken 3 times daily (for a total daily dose ranging from 600 mg to 1,200 mg). For weight loss, 100 mg alpha-lipoic acid (taken three times per day with meals), along with a reduced-calorie diet, has shown some benefit. For use as a general antioxidant, a lower dose (20 to 50 mg daily) is commonly recommended (although there is no evidence this offers any health benefit). You may be able to halve the dose when using the R-isomer-only form (see What to Consider When Using). 
Which is the best alpha-lipoic acid supplement?
Many products passed our tests of quality (see What CL Found). Among Approved products, ConsumerLab.com identified two as its Top Picks.-
What are the side-effects of alpha-lipoic acid?
Side effects of alpha lipoic acid such as skin rash and nausea have been reported. Alpha lipoic acid may also contribute to acid reflux, as it is an acid. It may also cause a strong urine odor. Because alpha-lipoic acid may help control blood sugar in diabetics, adjustments may be needed to anti-diabetic medication when using alpha-lipoic acid. Alpha-lipoic acid may interfere with thyroid function, medication and diagnostic tests. Although rare, alpha lipoic acid may cause insulin autoimmunity (see Concerns and Cautions).
