Alpha-Lipoic Acid
Evidence Fact Sheet
Thioctic Acid · R-ALA · Racemic ALA
Alpha-lipoic acid (thioctic acid) is a dual-soluble mitochondrial cofactor and antioxidant studied in diabetic neuropathy and cardiometabolic markers. Research dose ranges 300-1,800 mg/day (oral) or 600 mg/day IV. US DSHEA supplement; no EFSA health claim; China OTC-drug identity only.
Also known as: Thioctic acid · R-alpha-lipoic acid · 6,8-thioctic acid · ALA (not alpha-linolenic)
Overview
Alpha-lipoic acid (ALA; thioctic acid, also sold as R-ALA or racemic ALA) is a sulfur-containing compound that acts as a mitochondrial cofactor for the pyruvate and alpha-ketoglutarate dehydrogenase complexes and as a dual-soluble (aqueous and lipid) radical scavenger that helps recycle vitamins C and E and glutathione. In human research it has been studied mainly as an intravenous protocol for symptomatic diabetic peripheral neuropathy and as an oral antioxidant adjunct in metabolic conditions, with typical research doses of 600 mg/day IV for 3 weeks or oral doses spanning roughly 300-1,800 mg/day. Regulatory status differs sharply by market: in the US the oral form is a GRAS DSHEA dietary supplement permitted structure/function claims but is not an FDA-approved drug; the EU has adopted no authorized EFSA health claim; Brazil treats it as an RDC 243/2018 supplement; and in China its only domestic identity is as an OTC drug for diabetic neuropathy, with no compliant supplement route. This page reports research findings in studied populations and is not medical or dosing guidance.
Mechanism of Action
Mitochondrial cofactor for pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes · Direct radical scavenger in both aqueous and lipid compartments (dual-soluble antioxidant) · Recycles other antioxidants (vitamin C / E / glutathione) · NRF2 / endogenous antioxidant gene expression modulation
Body systems: Neurological & Cognitive · METABOLISM · Cellular Renewal
Evidence-Based Benefits
Each benefit below is anchored to a specific PubMed-indexed study. Effect sizes, sample sizes, and p-values are reported as published; no values are inferred. Honest negatives and null results are kept alongside the positive findings, and disease-research populations are described as such — Alpha-Lipoic Acid is not characterized as a treatment for any disease.
Diabetic Peripheral Neuropathy (Intravenous Protocol)
Meta-analysis supported- OR 4.03 (2.73-5.94)efficacy vs control
- 4.63 (3.58-5.67)median MNCV WMD
In this pooled analysis of 15 randomized trials of intravenous alpha-lipoic acid (300-600 mg/day for 2-4 weeks) in diabetic peripheral neuropathy, the treatment group showed faster nerve conduction velocities and a roughly four-fold higher odds of clinical efficacy versus control, with no serious adverse events reported. The strongest neuropathy evidence base is for the IV protocol, which is not equivalent to the oral supplement form.
Reported effect: Median MNCV weighted mean difference 4.63 (95% CI 3.58-5.67); efficacy odds ratio 4.03 (2.73-5.94) for ALA; 300-600 mg IV daily for 2-4 weeks
“Median MNCV 4.63 (95% confidence interval 3.58-5.67) ... Peroneal SNCV 3.65 (1.50-5.80) in favor of the treatment group ... 4.03 (2.73-5.94) for ALA ... No serious adverse events were observed during the treatment period”
Source: PMID 22837391 · Han 2012 · Eur J Endocrinol
Diabetic Polyneuropathy (Oral, Mixed Outcomes)
Meta-analysis supportedThis meta-analysis of 10 oral alpha-lipoic acid RCTs (1,242 patients) found favorable effects on the Total Symptom Score (with a dose-related trend), the Neuropathy Disability Score, and global satisfaction, but no favorable effect on VAS pain, vibration perception threshold, NIS-LL, or nerve conduction study results. The abstract reports the direction of effect qualitatively rather than a single pooled number, so no effect size is extracted here.
Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.
“ALA treatment produced favorable results for TSS (a dose-related trend was observed), NDS, and the global satisfaction score. ... For VAS, VPT, NIS-LL, and NCS results, ALA did not produce favorable results.”
Source: PMID 37630823 · Hsieh 2023 · Nutrients
Diabetic Peripheral Neuropathy (Oral, Cochrane)
Null / no benefit Meta-analysis supported- MD -0.16 (-0.83 to 0.51)TSS · 6 months
- moderate-certaintyGRADE evidence
This Cochrane systematic review (3 studies, 816 participants) concluded that oral alpha-lipoic acid probably has little or no effect on neuropathy symptoms (Total Symptom Score) at six months, with the confidence interval crossing zero and moderate-certainty evidence. This is the key honest negative for the oral form and contrasts with the more favorable short-term IV nerve-conduction data.
Reported effect: Mean difference -0.16 points (95% CI -0.83 to 0.51) on TSS at 6 months; 1 study, 330 participants; moderate-certainty evidence
“ALA compared with placebo probably has little or no effect on neuropathy symptoms measured by TSS (lower score is better) after six months (mean difference (MD) -0.16 points, 95% confidence interval (CI) -0.83 to 0.51; 1 study, 330 participants; moderate-certainty evidence).”
Source: PMID 38205823 · Baicus 2024 · Cochrane Database Syst Rev
Glucose Control & Lipids in Metabolic Disease
Meta-analysis supported- SMD -1.22 (-2.01 to -0.44)HbA1c · P=0.002
- SMD -0.76 (-1.15 to -0.36)HOMA-IR · P<0.001
Across 24 RCTs in patients with metabolic diseases, alpha-lipoic acid supplementation was associated with significant reductions in fasting glucose, insulin, HOMA-IR, HbA1c, and several lipid fractions, while HDL-cholesterol did not change significantly. These are pooled standardized mean differences in studied metabolic-disease populations, not a treatment claim.
Reported effect: HbA1c SMD -1.22 (95% CI -2.01 to -0.44, P=0.002); HOMA-IR SMD -0.76 (-1.15 to -0.36, P<0.001); fasting glucose SMD -0.54 (-0.89 to -0.19, P=0.003); HDL SMD 0.57 (-0.14 to 1.29, P=0.11, NS)
“HbA1c: SMD -1.22; 95% CI, -2.01, -0.44; P = 0.002 ... HOMA-IR: SMD -0.76; 95% CI, -1.15, -0.36; P < 0.001 ... Fasting glucose: SMD -0.54; 95% CI, -0.89, -0.19; P = 0.003 ... HDL-cholesterol: SMD 0.57; 95% CI, -0.14, 1.29; P = 0.11”
Source: PMID 29990473 · Akbari 2018 · Metabolism
Cardiometabolic Risk Factors (Dose-Response)
Meta-analysis supported- WMD -5.28 mg/dLfasting glucose · P<0.001
- WMD -0.64 kgbody weight · P=0.002
In a large dose-response meta-analysis of 63 RCTs, alpha-lipoic acid was associated with small but significant reductions in fasting blood glucose, body weight, BMI, total cholesterol, and triglycerides, while blood pressure showed no substantial effect. The effect sizes are modest, reflecting an adjunctive metabolic signal rather than a large clinical effect.
Reported effect: Fasting glucose WMD -5.28 mg/dL (95% CI -7.21 to -3.35, P<0.001); body weight WMD -0.64 kg (-1.04 to -0.24, P=0.002); BMI WMD -0.27 kg/m2 (-0.44 to -0.10, P=0.002); blood pressure: no substantial effect
“Fasting Blood Glucose: WMD: -5.28 mg/dL, 95 % CI: -7.21, -3.35; P < 0.001 ... Body Weight: WMD: -0.64 kg, 95 % CI: -1.04, -0.24; P = 0.002 ... BMI: WMD: -0.27 kg/m2, 95 % CI: -0.44, -0.10; P = 0.002 ... Blood Pressure: no substantial effect”
Source: PMID 41077538 · Mohammadi 2026 · Nutr Metab Cardiovasc Dis
Cardiometabolic Markers in Overweight/Obese Adults
Null / no benefit Meta-analysis supported- SMD -0.23 (-0.60 to 0.15)HOMA-IR · p=0.23 NS
In a meta-analysis restricted to 11 RCTs in overweight or obese adults (704 participants), alpha-lipoic acid showed no significant association with triglycerides, total cholesterol, HDL-C, LDL-C, HOMA-IR, or fasting blood glucose. This is an honest null finding: the metabolic signal seen in disease populations did not reach significance for intermediate markers in this overweight/obese group.
Reported effect: No significant associations: TG SMD -0.08 (95% CI -0.24 to 0.09, p=0.36); HOMA-IR SMD -0.23 (-0.60 to 0.15, p=0.23); FBS SMD 0.13 (-0.16 to 0.41, p=0.39)
“no significant associations were detected between ALA supplementation and changes in intermediate disease markers, including triglyceride (TG) (standardized mean difference (SMD): -0.08, 95% CI: -0.24 to 0.09, p=0.36 ... homeostasis model assessment of insulin resistance (HOMA-IR) (SMD: -0.23, 95% CI: -0.60 to 0.15, p=0.23), and fasting blood glucose (FBS) (SMD: 0.13, 95% CI: -0.16 to 0.41, p=0.39)”
Source: PMID 40180416 · Luo 2025 · BMJ Open
Dosage (research context · not a recommendation)
600 mg/day intravenous for 3 weeks established the symptomatic improvement in diabetic polyneuropathy (Ziegler 2004 PMID 14984445 Diabetic Medicine meta-analysis of ALADIN I + ALADIN III + SYDNEY + NATHAN II · n=1,258 patients · responder rates 52.7% ALA vs 36.9% placebo · 24.1% relative difference). Oral 600-1,800 mg/day used in some trials but evidence base is strongest at the IV 600 mg/day protocol
Regulatory Status · 4 Markets
- US · FDA
- GRAS · DSHEA dietary supplement (oral form) · structure/function claims permitted; not an FDA-approved drug for any condition in the US
- EU · EFSA
- No standalone EFSA Reg 432/2012 authorized health claim adopted for alpha-lipoic acid
- CN · China
- China: alpha-lipoic acid not in health-food raw-material catalogue nor a novel/general-food additive; domestic identity is OTC drug (diabetic neuropathy); no compliant domestic supplement route, only cross-border e-commerce.
- BR · ANVISA
- RDC 243/2018 dietary supplement · no IN 28/2018 Anexo V alegação funcional for ácido alfa-lipoico
Safety
Generally well tolerated; rare biotin metabolism interaction (high-dose ALA may reduce biotin status); insulin sensitisation effect requires monitoring in diabetic patients adjusting hypoglycaemic medications; the dietary supplement form is not equivalent to the IV protocol used in the strongest evidence base
Related
Goals: longevity-stack · inflammation-relief
Lifestyles: senior-60-plus
References
PubMed-indexed citations anchoring the benefit findings above. Effect sizes are reported as published.
- PMID 22837391 · Han 2012 · Eur J Endocrinol — Diabetic Peripheral Neuropathy (Intravenous Protocol)
- PMID 37630823 · Hsieh 2023 · Nutrients — Diabetic Polyneuropathy (Oral, Mixed Outcomes)
- PMID 38205823 · Baicus 2024 · Cochrane Database Syst Rev — Diabetic Peripheral Neuropathy (Oral, Cochrane)
- PMID 29990473 · Akbari 2018 · Metabolism — Glucose Control & Lipids in Metabolic Disease
- PMID 41077538 · Mohammadi 2026 · Nutr Metab Cardiovasc Dis — Cardiometabolic Risk Factors (Dose-Response)
- PMID 40180416 · Luo 2025 · BMJ Open — Cardiometabolic Markers in Overweight/Obese Adults
Frequently Asked Questions
1. Is intravenous and oral alpha-lipoic acid the same thing for neuropathy research?
No. The most favorable diabetic neuropathy data come from intravenous protocols (300-600 mg/day for 2-4 weeks), where Han 2012 (PMID 22837391) pooled 15 RCTs and reported faster nerve conduction and an efficacy odds ratio of 4.03 (95% CI 2.73-5.94). The oral supplement form is a different exposure, and the Cochrane review by Baicus 2024 (PMID 38205823) found oral ALA probably has little or no effect on neuropathy symptoms at six months (TSS mean difference -0.16, 95% CI -0.83 to 0.51, moderate-certainty).
2. Does alpha-lipoic acid improve blood sugar and lipids?
In studied metabolic-disease populations, Akbari 2018 (PMID 29990473) pooled 24 RCTs and reported reductions in HbA1c (SMD -1.22, 95% CI -2.01 to -0.44, P=0.002), HOMA-IR (SMD -0.76, P<0.001) and several lipid fractions, with HDL unchanged (P=0.11). A larger dose-response meta-analysis (Mohammadi 2026, PMID 41077538, 63 RCTs) found smaller effects such as fasting glucose -5.28 mg/dL. These are research associations in studied groups, not a treatment claim.
3. Are there honest negative findings for alpha-lipoic acid?
Yes. The Cochrane review (Baicus 2024, PMID 38205823) concluded oral ALA probably has little or no effect on neuropathy symptoms at six months. Separately, Luo 2025 (PMID 40180416), an 11-RCT meta-analysis in 704 overweight or obese adults, found no significant association with triglycerides, cholesterol, HOMA-IR (SMD -0.23, p=0.23), or fasting glucose. Effects appear context-dependent rather than universal.
4. What is the regulatory status of alpha-lipoic acid?
In the US the oral form is a GRAS DSHEA dietary supplement permitted structure/function claims, but it is not an FDA-approved drug for any condition. The EU has adopted no authorized EFSA health claim, Brazil treats it as an RDC 243/2018 supplement, and in China its only domestic identity is as an OTC drug for diabetic neuropathy with no compliant supplement route. Research doses span roughly 300-1,800 mg/day orally or 600 mg/day IV; this page reports evidence, not dosing guidance.
Last evidence review: 2026-06-04