Alpha-Lipoic Acid

non-nutrient/non-botanical(R)-lipoic acid

Take with food

What is it

Alpha-lipoic acid (ALA) is a sulfur-containing fatty acid synthesized in small amounts by the body and obtained from foods such as red meat, organ meats, and certain vegetables. It functions both as an essential cofactor in mitochondrial energy production and as a potent antioxidant.

How it works

Alpha-lipoic acid is a cofactor for mitochondrial enzymes, particularly pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, which are essential for converting carbohydrates and amino acids into energy. Its unique chemistry allows it to function in both the aqueous cytoplasm and lipid-rich cell membranes, earning it the label 'universal antioxidant.' ALA exists in oxidized and reduced forms (dihydrolipoic acid), and both forms scavenge free radicals. It can also regenerate other antioxidants including vitamin C, vitamin E, and glutathione, amplifying the cellular antioxidant network. Supplemental ALA appears to influence glucose uptake by enhancing insulin signaling and may chelate certain metals. When taken orally, ALA is rapidly absorbed but has poor bioavailability and a short half-life. The R-isomer occurs naturally and is generally considered more bioactive than the S-isomer; many supplements contain a racemic mix of both.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Diabetic peripheral neuropathy

Grade B

Good evidence

Multiple clinical trials, including the ALADIN series, suggest that 600 mg of intravenous or oral ALA daily can reduce symptoms such as burning, numbness, and pain associated with diabetic neuropathy. Effects are generally modest and most pronounced with parenteral administration; oral evidence is weaker but still suggestive.

Insulin sensitivity and glucose control

Grade C

Moderate evidence

Research indicates ALA may modestly improve insulin sensitivity and fasting glucose in people with type 2 diabetes, but results are inconsistent across trials and the magnitude of effect is small. It is not a replacement for first-line diabetes therapy.

Antioxidant and anti-inflammatory support

Grade C

Moderate evidence

Mechanistic studies and some small clinical trials suggest ALA reduces markers of oxidative stress and certain inflammatory cytokines. Whether this translates to meaningful long-term health outcomes is unclear.

Weight management

Grade D

Mixed evidence

Some meta-analyses report a small reduction in body weight with ALA supplementation, on the order of 1 to 2 kg over several months. Effects are modest, inconsistent, and not a substitute for diet and activity changes.

Cognitive function

Grade F

Limited evidence

Preclinical and small clinical studies hint at neuroprotective effects, but robust human evidence for cognitive benefits is lacking. Claims for memory or dementia prevention are not supported by high-quality data.

3 commercial forms

Racemic ALA (R/S mix)

Standard form in most supplements; contains both R and S isomers.

Less expensive and widely available. About half of the absorbed dose is the biologically active R-form.

R-lipoic acid

The natural, biologically active isomer; generally absorbed more efficiently than the racemic mix.

Often marketed as more potent. Stabilized forms (Na-RALA) further improve absorption but cost more.

Sodium R-lipoate (Na-RALA)

A stabilized salt form designed for better absorption and higher peak plasma levels.

Premium form sometimes used in clinical research for diabetic neuropathy.

Dosage

There is no RDA for alpha-lipoic acid. Clinical trial doses range from 200 to 1,800 mg per day, often divided into two or three doses. For neuropathy support, 600 mg daily has been the most commonly studied dose. For general antioxidant support, 100 to 300 mg per day is typical. Higher doses are usually reserved for specific clinical indications and should be supervised.

When and how to take it

WHEN: Take ALA on an empty stomach, ideally 30 minutes before meals or two hours after, for best absorption. If divided into multiple doses, space them throughout the day. HOW: Some sources recommend taking ALA with food to reduce GI upset; this may slightly reduce absorption but improves tolerability. Avoid taking with high-iron or high-calcium foods, which can bind ALA and impair absorption. Separate from thyroid medications by at least four hours.

Food sources

Food	Amount	%DV
Red meat (especially organ meats like liver, kidney, heart)	3 oz	—
Spinach	1 cup cooked	—
Broccoli	1 cup	—
Brussels sprouts	1 cup	—
Tomato	1 medium	—
Peas	1/2 cup	—

Safety

Alpha-lipoic acid is generally well tolerated. The most common side effects are mild and include skin rash, nausea, and gastrointestinal upset. High doses may rarely cause hypoglycemia, particularly in people with diabetes. There is no established Tolerable Upper Intake Level. Case reports describe rare instances of insulin autoimmune syndrome (hypoglycemia from anti-insulin antibodies), particularly in individuals of Asian ancestry with specific HLA genotypes. Reports of overdose have linked very high acute ingestion to seizures and metabolic acidosis.

Who should be cautious

People with diabetes should monitor blood glucose closely, as ALA may increase hypoglycemia risk when combined with diabetes medications. Those with thyroid conditions taking levothyroxine should separate ALA from thyroid medication. Pregnant and breastfeeding women should avoid supplementation due to insufficient safety data. People with thiamine deficiency, including those with chronic alcohol use disorder, should address thiamine status before supplementing. Individuals of Korean or Japanese descent may have higher risk of insulin autoimmune syndrome.

Interactions

ALA may enhance the blood-glucose-lowering effects of insulin and oral diabetes medications, increasing the risk of hypoglycemia. It may interact with thyroid medications such as levothyroxine, potentially affecting their absorption or activity, so doses should be separated by several hours. ALA may also affect chemotherapy regimens through its antioxidant activity; cancer patients should consult their oncologist. Alcohol can deplete thiamine, which interacts with ALA's metabolic functions.

Frequently asked questions

What's the difference between R-ALA and regular ALA?⌄

Regular ALA is a 50/50 mix of R and S isomers; only the R-form occurs naturally and is biologically active in mitochondrial enzymes. R-ALA supplements deliver the active form directly and tend to be better absorbed, though they cost more.

Can ALA help me lose weight?⌄

Some meta-analyses suggest modest weight loss of about 1 to 2 kg, but effects are small and inconsistent. ALA is not a weight-loss treatment and should not replace diet and exercise.

Does ALA lower blood sugar?⌄

ALA may improve insulin sensitivity in people with type 2 diabetes, but effects are typically modest. People taking diabetes medications should monitor blood glucose to avoid hypoglycemia.

Should I take ALA with food?⌄

Empty-stomach dosing improves absorption, but if you experience nausea, taking it with a small meal is acceptable. Separate from thyroid medication by several hours.

Is alpha-lipoic acid the same as omega-3 alpha-linolenic acid?⌄

No. Despite the similar abbreviation 'ALA,' alpha-lipoic acid is a sulfur-containing antioxidant cofactor, while alpha-linolenic acid is a plant-based omega-3 fatty acid found in flaxseed and walnuts.

References

Wikidata: Lipoic acid — Wikidata link
PubChem: Alpha-lipoic acid (CID 864) — PubChem link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.