Alpha-Lipoic Acid: Why "600 mg" Is Really 300 mg of Active R-ALA
Alpha-lipoic acid (ALA) is an antioxidant your body makes, also sold in capsules and mostly studied for nerve pain from diabetes. A 2024 Cochrane review found it probably has little or no effect on those symptoms after six months. Regular ALA is half R-ALA, so 600 mg holds 300 mg. Our pick: BulkSupplements Alpha Lipoic Acid.
By Erin Rose Updated October 19, 2026 How we score
What to buy
BulkSupplements Alpha Lipoic Acid is our pick. Two capsules give 600 mg for $0.22 a day at its own price, the least of the products we compare, and it is the alpha-lipoic acid our readers buy most.
BulkSupplements Alpha Lipoic Acid
Our pick
Want one on a public testing list? Thorne Alpha-Lipoic Acid is on NSF/ANSI 173, which checks the capsule holds what the label says.
Thorne Alpha-Lipoic Acid
NSF/ANSI 173
Where to go next
- Best alpha-lipoic acid: the products we compared, ranked.
- Alpha-lipoic acid dosage guide: how much to take, with a calculator.
What alpha-lipoic acid does
Alpha-lipoic acid is an antioxidant the body makes in small amounts. Regular ALA in capsules is a 50/50 mix of two mirror-image forms, R and S. R-ALA is the R form alone. The reviews we cite looked mostly at nerve pain in people with diabetes.
| Goal | Evidence | What trials found |
|---|---|---|
| Nerve pain from diabetes | Mixed | A 2024 Cochrane review found ALA by mouth probably has little or no effect on symptoms after six months. A 2023 review of 10 trials found some symptom scores improved, more at higher doses. |
| Blood sugar | Some | In people with diabetes or similar conditions, a review of trials found lower fasting blood sugar. |
| Weight | Small effect | A review of 12 trials found weight dropped slightly, by less than a kilogram on average. |
| Heart nerve damage from diabetes | One trial | One 4-month trial in 73 adults with type 2 diabetes, at 800 mg a day, found slightly better results on a heart-rhythm test. |
How much to take
Trials gave 600 to 1,800 mg a day. Start with 600 mg: two capsules of our pick. See the dosage guide.
Is alpha-lipoic acid safe?
The Cochrane review found probably little or no difference in people stopping for side effects, though the range was wide (Baicus 2024). A few things to check:
- Diabetes medicine: ALA may lower blood sugar (Akbari 2018). Ask your doctor before adding it.
- A rare immune reaction can cause low blood sugar. Europe’s food safety agency reviewed 49 cases: the risk is likely in people with certain genes, which no simple test finds, and every case cleared after stopping ALA (EFSA 2021).
- Pregnant or breastfeeding: ask your doctor first.
Questions people ask
Is R-ALA the only form that works?
That is not shown. A stabilized R form reached higher blood levels in a small study (Carlson 2007), but we found no trial showing it works better.
Can I get alpha-lipoic acid from food?
Your body makes small amounts, and some foods have a little. No link between ALA in food and the rare immune reaction has been found (EFSA 2021).
Sources
- Baicus C, et al. “Alpha-lipoic acid for diabetic peripheral neuropathy.” Cochrane Database Syst Rev. 2024. PubMed 38205823
- Hsieh RY, et al. “Effects of Oral Alpha-Lipoic Acid Treatment on Diabetic Polyneuropathy: A Meta-Analysis and Systematic Review.” Nutrients. 2023. PubMed 37630823
- Akbari M, et al. “The effects of alpha-lipoic acid supplementation on glucose control and lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials.” Metabolism. 2018. PubMed 29990473
- Namazi N, et al. “Alpha-lipoic acid supplement in obesity treatment: A systematic review and meta-analysis of clinical trials.” Clin Nutr. 2018. PubMed 28629898
- Ziegler D, et al. “Effects of treatment with the antioxidant alpha-lipoic acid on cardiac autonomic neuropathy in NIDDM patients. A 4-month randomized controlled multicenter trial (DEKAN Study). Deutsche Kardiale Autonome Neuropathie.” Diabetes Care. 1997. PubMed 9051389
- Carlson DA, et al. “The plasma pharmacokinetics of R-(+)-lipoic acid administered as sodium R-(+)-lipoate to healthy human subjects.” Altern Med Rev. 2007. PubMed 18069903
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (Turck D, et al.). “Scientific opinion on the relationship between intake of alpha-lipoic acid (thioctic acid) and the risk of insulin autoimmune syndrome.” EFSA J. 2021. PubMed 34122657