Alpha-lipoic acid (ALA) is one of the body's natural antioxidants most widely used as a food supplement for its broad-spectrum action against oxidative stress and its support of cellular energy metabolism. In the medical setting, it has also been the subject of decades of research at high doses and under clinical supervision in people with diabetes and associated peripheral nerve problems. This page covers how it works, the commercial forms (R-ALA and racemic), the studied doses, the precautions to keep in mind, and where it fits within the Pleniage portfolio.
What is alpha-lipoic acid?
Alpha-lipoic acid (also called thioctic acid, abbreviated ALA) is a small molecule that the human body produces naturally in small amounts from fatty acids and the amino acid cysteine. It serves a dual function within the cell: on one hand it acts as an indispensable piece in the workings of energy metabolism; on the other, it functions as a broad-spectrum antioxidant capable of protecting the cell from several types of oxidative damage. We explain each of these functions in detail further on.
It is also found in very small amounts in some foods — spinach, broccoli, organ meats such as kidney, tomato and yeast — but the amount obtained through diet is modest and far below the doses used in clinical research. Because the body's internal production also declines with age, ALA has been developed as a concentrated ingredient in food supplements.
A useful technical note: commercial ALA supplements are chemically synthesized in the laboratory; they are not plant extracts. The resulting compound is biochemically identical to the one the body produces, and that explains why supplemental ALA powder always has the same characteristic lemon-yellow color and a standardized purity.
What is it for? Benefits according to clinical evidence
Informational note: The information in this section is for educational purposes and is based on published scientific research. It does not constitute medical advice or an individual therapeutic recommendation. The conditions mentioned require specialized medical diagnosis and follow-up. Always consult your doctor before starting any supplementation, especially if you have diagnosed diabetes or take medication.
Research in peripheral neuropathy associated with diabetes (the area with the most evidence)
The largest body of clinical evidence on ALA corresponds to research in patients with diabetes who present peripheral neuropathy — the damage to the nerves of the feet, legs and hands associated with long-standing, poorly controlled diabetes, with symptoms such as pain, tingling and loss of sensation. The ALADIN series of studies (an acronym for "Alpha-Lipoic Acid in Diabetic Neuropathy"), a set of multicenter randomized clinical trials led by Ziegler's group in Germany, evaluated ALA by the oral and intravenous routes at therapeutic doses (600 mg/day) and under medical supervision in this diagnosed population.
A meta-analysis — that is, a statistical analysis that combines the results of several clinical trials — published in Diabetic Medicine (Ziegler et al., 2004) consolidated the results of the ALADIN series and documented significant effects on neuropathic symptoms in diagnosed patients, at doses of 600 mg/day. A more recent meta-analysis published in Nutrients (Hsieh et al., 2023) confirmed the direction and magnitude of the effect in a broader population, and an even more recent analysis published in the Canadian Journal of Diabetes (Prado and Adiao, 2024) compared ALA against another antioxidant (γ-linolenic acid) with results favorable to ALA.
In some European countries such as Germany or Italy, ALA is authorized as a prescription medication (not as a food supplement) for this specific clinical indication. This authorization corresponds to ALA used at therapeutic doses and under medical supervision, and does NOT carry over to the use of ALA as a food supplement in general supplementation.
Oxidative stress (blood markers)
Oxidative stress is the imbalance between the production of harmful reactive molecules (so-called free radicals) and the body's capacity to neutralize them, and it is implicated in cellular aging and in numerous chronic diseases. ALA consistently reduces the markers of oxidative stress measured in blood and increases total antioxidant capacity. The effects are clearer in people with a high baseline oxidative burden (type 2 diabetes, metabolic syndrome, chronic cardiovascular disease) than in healthy people with normal values.
Lipid profile and blood glucose control
A meta-analysis published in the European Journal of Pharmacology (Haghighatdoost and Hariri, 2019) evaluated the effect of ALA on the lipid profile and documented modest reductions in triglycerides and total cholesterol, with no significant effect on HDL (so-called "good cholesterol"). As for glycemic control, an integrative review published in Nutrients (Capece et al., 2022) synthesized the available evidence and described moderate effects on insulin sensitivity in people with insulin resistance.
Does it help with weight loss?
This section deserves explicit honesty because of the frequent marketing of ALA as a "weight-loss aid." The available clinical evidence is modest and heterogeneous. A meta-analysis published in Clinical Nutrition (Namazi et al., 2018) documented small reductions in body weight and body mass index with ALA supplementation versus placebo in people who are overweight, but the magnitude of the effect was clinically modest (typically less than 1 kg over durations of 8-24 weeks). ALA is not a weight-loss agent on its own: the interventions with the most evidence for weight management remain a sustained caloric deficit, regular physical activity and, when indicated, specialized medical or nutritional follow-up.
How it works: mechanism of action
ALA has three complementary mechanisms of action. The best known is its role as an essential piece of energy metabolism in the mitochondria; the most singular is its ability to act as an antioxidant in two types of cellular environments at the same time and to regenerate other antioxidants; the third is its ability to modulate inflammation at the cellular level.
Essential piece of energy metabolism
ALA acts as an enzymatic cofactor — that is, a molecule that enzymes need to function correctly — in several enzyme complexes inside the mitochondria, the cellular structures responsible for generating the energy the cell uses (in the form of a molecule called ATP). Without ALA, these complexes do not function correctly and mitochondrial energy production is compromised.
An important clarification is in order: the amount of ALA the body produces internally already covers the usual enzymatic need, so the dose added through supplementation does not provide additional cofactor to these complexes (which are already saturated). Supplemental ALA acts mainly as a free antioxidant in circulation — the other role, described next.
A "dual-solubility" antioxidant that regenerates other antioxidants
Most antioxidants only work in one type of cellular environment. Glutathione and vitamin C operate in the water inside the cell (the cytoplasm); vitamin E and coenzyme Q10 do so in the fatty membranes (the cell and mitochondrial walls). ALA and its reduced form — called dihydrolipoate or DHLA — have an uncommon property: they are soluble in both water and fats, which allows them to act simultaneously in both environments.
From that property arises its most singular action: ALA can regenerate other antioxidants that have already been oxidized, returning them to their active form so they can work again. In practice, it regenerates the vitamin E used in cell membranes and, at the same time, recovers the oxidized glutathione in the cytoplasm. Because of this effect, it has come to be called the "universal antioxidant" in the scientific literature. To learn more about the main intracellular antioxidant regenerated by ALA, see the Glutathione page.
Other actions: metal chelation and inflammatory modulation
ALA has a chelating capacity over some metal ions (iron, copper): it binds to them and reduces their availability to take part in harmful oxidative reactions. It also modulates the activation of the NF-κB factor — a master regulator of the inflammatory response at the cellular level — helping to reduce the transcription of pro-inflammatory genes. These complementary mechanisms support its use in conditions with a chronic low-grade inflammatory component.
Commercial forms: R-ALA vs racemic ALA
Like many biological molecules, ALA exists in two mirror-image versions — chemists call them enantiomers or "optical isomers": the R-ALA form is the one the body produces and recognizes as active, while S-ALA is its mirror version, synthetic and not present in the body. Industrial chemical synthesis produces both in equal parts — a 50:50 mixture called racemic ALA — whereas pure R-ALA requires additional purification processes.
| Form | Composition | Practical notes |
|---|---|---|
| Racemic ALA | 50% R-ALA + 50% S-ALA | Standard and most affordable commercial form. The vast majority of generic supplements. |
| Pure R-ALA | 100% R-ALA | Greater bioavailability per milligram (approximately double that of the racemic form). More expensive and less stable in storage. |
| Stabilized R-ALA | R-ALA + sodium salt (Na-RALA) or registered trademark (Bio-Enhanced®) | Stabilization to prevent the loss of activity of pure R-ALA during storage. |
An important practical note: most of the reference clinical trials (including the ALADIN studies on diabetic neuropathy) were carried out with racemic ALA. That is why the evidence-based doses cited in the following section correspond to the racemic form, unless otherwise indicated. If pure R-ALA is used, the equivalent dose is usually approximately half, because of its greater bioavailability.
Doses studied in clinical research
| Studied indication | Typical dose of racemic ALA | Duration |
|---|---|---|
| Peripheral diabetic neuropathy (ALADIN) | 600 mg/day orally or intravenously | 3 weeks to 7 months |
| Oxidative stress / blood markers | 300-1,200 mg/day orally | 4-12 weeks |
| Lipid and glycemic profile | 300-1,800 mg/day orally | 8-12 weeks |
| General antioxidant / maintenance | 100-300 mg/day orally | ongoing |
The doses most used in modern research on diabetic neuropathy range between 600 and 1,200 mg/day of racemic ALA. When pure R-ALA is used, the equivalent doses are usually approximately half, because of its greater bioavailability.
Important note: the doses mentioned correspond to those used in clinical research, mainly in people with a medical diagnosis (diabetic neuropathy). They do not constitute a recommendation of an individual dose. Consult your doctor or pharmacist before starting any supplementation, especially if you have diagnosed diabetes or take blood-glucose-lowering medication.
Safety and interactions
ALA has a generally favorable safety profile at the usual supplementation doses, with some specific precautions worth knowing.
Common adverse effects
At the usual doses (up to 600 mg/day) the reported adverse effects are generally mild and infrequent: gastrointestinal discomfort (nausea, dyspepsia) and, occasionally, some skin rash. Taking it on an empty stomach maximizes absorption but increases the likelihood of digestive discomfort; taking it with meals reduces absorption but improves tolerance.
Relevant drug interactions
- Blood-glucose-lowering agents (insulin, sulfonylureas, metformin): ALA may enhance the blood-glucose-lowering effect. People with type 1 or type 2 diabetes should monitor their blood glucose and consult their doctor before starting supplementation; it may be necessary to adjust the medication dose.
- Levothyroxine (thyroid hormone): ALA may interfere with the absorption of levothyroxine if taken together. It is recommended to separate the two by at least 4 hours.
- Chemotherapy: people undergoing cancer treatment should consult their oncologist before any supplementation with antioxidants.
- Anticoagulants: a theoretically possible effect on platelet function; caution in anticoagulated patients.
Rare risk: autoimmune insulin syndrome (Hirata)
Autoimmune insulin syndrome (AIS), also called Hirata disease after the physician who originally described it in Japan in 1970, is a condition in which the immune system produces autoantibodies — antibodies mistakenly directed against the person's own body, in this case against insulin — causing episodes of spontaneous hypoglycemia (low blood sugar). Cases associated with the consumption of ALA supplements have been described, but it is a relatively rare association in absolute terms (dozens to a few hundred cases described in the world literature) and clinically relevant only in people with a genetic predisposition.
The factor that most predisposes to it is the presence of certain hereditary variants of the HLA system, a set of genes that regulates each person's immune recognition. In Japanese and Korean populations it has been associated with the HLA-DRB1*04:06 variant; in European Caucasian patients the HLA-DRB1*04:03 variant has been identified (Gullo et al., 2014). A more recent analytical series published in the Journal of Clinical Pharmacy and Therapeutics (Li et al., 2021) described the clinical characteristics in 37 patients and observed that the hypoglycemia disappears within variable time frames (days to months) after discontinuing ALA or with specific medical treatment.
Practical recommendation: people with a personal or family history of autoimmune diseases — especially thyroid ones such as Graves-Basedow disease or Hashimoto's thyroiditis — and people of Asian origin should consult their doctor before starting supplementation with ALA. It is not a general contraindication for the rest of the population.
Pregnancy and breastfeeding
The evidence on the safety of supplemental ALA during pregnancy and breastfeeding is limited. It is recommended to avoid concentrated ALA supplements in these situations unless there is an express medical indication.
How to choose an ALA supplement
Key technical criteria for selecting an ALA supplement with pharmaceutical quality:
- Enantiomer form: pure R-ALA (more expensive but greater bioavailability) or racemic ALA (the standard used in most clinical trials). Stabilized R-ALA (Bio-Enhanced®, Na-RALA) prevents the loss of activity of pure R-ALA during storage.
- Dose per capsule: 100-600 mg is the usual range. Check that it is consistent with the dose your doctor or the directions for use recommend.
- Purity and traceability: third-party certificates of analysis (USP, NSF) guarantee the absence of contaminants and the real declared dose.
- Formulation: free ALA or sodium salts. Avoid formulations with unnecessary additives (titanium dioxide, excess magnesium stearate, artificial colorants).
- Consistency with your situation: if you have diagnosed diabetes, neuropathy or other conditions, the choice of dose and form should align with your doctor's indication.
ALA in the Pleniage portfolio
In the formulation of PLENIAGE® ENERGY PRO, alpha-lipoic acid (175 mg as racemic ALA) is incorporated together with magnesium citrate, a complete B complex (B1, B2, B3, B5, B6, B12), vitamin C, vitamin E and biotin. ALA contributes its distinctive characteristic as a dual-solubility antioxidant and support for energy metabolism, complementing the enzymatic cofactors of metabolism (B vitamins and magnesium) and the water-soluble (vitamin C) and fat-soluble (vitamin E) antioxidants of the formula.
The 175 mg dose is designed for a general antioxidant maintenance and mitochondrial support strategy within a multi-ingredient formula, not for a specific clinical indication such as diabetic neuropathy (which typically requires significantly higher doses and medical supervision). Each ingredient has individual scientific research; the specific combination of this formula has not been the subject of its own clinical trial.
This page is part of the Energy and performance cluster. To learn more about other related components, see the Coenzyme Q10 page (a complementary mitochondrial antioxidant regenerated by ALA) and the Glutathione page (the main intracellular antioxidant regenerated by ALA).
Frequently asked questions about alpha-lipoic acid
Is it written alpha-lipoic acid or alpha lipoic acid?
Both forms are commonly used. The canonical editorial form in the scientific literature is "alpha-lipoic acid" (with a hyphen), following conventional chemical nomenclature. The form "alpha lipoic acid" (without a hyphen) is more popular in online searches and frequently appears in colloquial contexts. The three variants refer to the same molecule. The alternative official chemical name is "thioctic acid", used especially in older European literature and in some pharmaceutical presentations.
What is alpha-lipoic acid for?
As a food supplement, it is used for its broad-spectrum antioxidant action and its support of cellular energy metabolism: ALA acts simultaneously in the cell's water-based and lipid-based compartments, and regenerates other oxidized antioxidants (glutathione, vitamin E, vitamin C, coenzyme Q10). In addition, the available studies document effects on markers of oxidative stress in blood and modest effects on the lipid profile and insulin sensitivity. In the medical setting, ALA has a long track record of clinical research in patients with diabetes and peripheral neuropathy (ALADIN studies), where it is used at therapeutic doses (600 mg/day) and under medical supervision; in some European countries it is authorized as a prescription medication for that indication. It is NOT a weight-loss agent on its own: the evidence on weight loss is modest and clinically of little relevance.
How much ALA is safe to take per day?
The usual maintenance doses range between 100 and 300 mg/day of racemic ALA. The therapeutic doses in peripheral diabetic neuropathy used in the ALADIN studies are 600 mg/day. Up to 1,800 mg/day has been used in clinical research with generally good tolerance. People with diagnosed diabetes should monitor their blood glucose and consult their doctor before supplementing, since ALA may enhance the effect of blood-glucose-lowering medication. People on levothyroxine treatment should separate the intake of ALA and levothyroxine by at least 4 hours.
What is the difference between R-ALA and racemic ALA?
Racemic ALA is the standard commercial form and consists of a 50:50 mixture of the two enantiomers (mirror versions) of alpha-lipoic acid: R-ALA and S-ALA. Pure R-ALA is the biologically active natural form and has approximately double the bioavailability per milligram compared with the racemic form, but it is more expensive and less stable in storage. The classic clinical studies (including the ALADIN ones) used racemic ALA, so the evidence-based doses refer mostly to that form. If pure R-ALA is used, an equivalent dose would be approximately half of the racemic one.
Does ALA have contraindications?
Yes, several relevant ones. People with type 1 or type 2 diabetes should monitor their blood glucose (additional blood-glucose-lowering effect). Those taking levothyroxine should separate the intakes by at least 4 hours. People with a personal or family history of autoimmune diseases — especially thyroid ones such as Graves-Basedow disease or Hashimoto's thyroiditis — and people of Asian origin should consult their doctor because of the rare but documented risk of autoimmune insulin syndrome (Hirata). People undergoing cancer treatment, pregnant women, those breastfeeding, or those on anticoagulants should consult before starting supplementation.
Why is ALA said to be a "universal antioxidant"?
Because, unlike most antioxidants, it can act both in the water inside the cell and in the fatty membranes. This dual solubility allows it to work simultaneously in both cellular environments and, above all, to regenerate other antioxidants that have already been oxidized (glutathione, vitamin C, vitamin E, coenzyme Q10), returning them to their active form. It is one of the few of the body's natural antioxidants with this "recycling" property of other antioxidant defenses.
What is Hirata syndrome and should I be worried?
Autoimmune insulin syndrome (Hirata) is a rare condition in which the body produces antibodies against endogenous insulin, causing episodes of spontaneous hypoglycemia. Cases associated with the consumption of ALA supplements have been described, especially in people with a genetic predisposition (HLA-DRB1*04:06 variants in Asians and *04:03 in European Caucasians) or with a history of autoimmune diseases (especially thyroid ones). In absolute terms it is relatively rare: dozens to a few hundred cases described in the world literature. If you do not belong to these risk groups, the usual maintenance doses are generally safe. If you belong to one of the risk profiles, consult your doctor before starting supplementation.
Alpha-lipoic acid is one of the body's natural antioxidants with the largest accumulated body of clinical evidence. Its most strongly supported indication — decades of clinical trials from the ALADIN series and recent meta-analyses — is the complementary symptomatic treatment of peripheral diabetic neuropathy at doses of 600 mg/day. In general maintenance supplementation (100-300 mg/day) it has a favorable safety profile, with specific precautions in people with diabetes (because of its additional effect on blood glucose), people on levothyroxine treatment, and genetic profiles predisposing to Hirata syndrome. If you are interested in exploring antioxidant strategies and mitochondrial support further, consult your doctor or pharmacist to assess whether ALA supplementation is appropriate for your situation.
At PLENIAGE® we publish scientific content on evidence-based supplementation. You can explore the Energy and performance cluster for more related pages and articles.
References
The statements in the article are based on the available scientific literature. The key verified references that support the main claims about alpha-lipoic acid are listed below.
- Ziegler D, Nowak H, Kempler P, Vargha P, Low PA. Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: a meta-analysis. Diabet Med. 2004;21(2):114-121. PMID: 14984445.
- Hsieh RY, Huang IC, Chen C, Sung JY. Effects of Oral Alpha-Lipoic Acid Treatment on Diabetic Polyneuropathy: A Meta-Analysis and Systematic Review. Nutrients. 2023. PMID: 37630823.
- Prado MB Jr, Adiao KJB. Ranking Alpha Lipoic Acid and Gamma Linolenic Acid in Terms of Efficacy and Safety in the Management of Adults With Diabetic Peripheral Neuropathy: A Systematic Review and Network Meta-analysis. Can J Diabetes. 2024. PMID: 38295879.
- Haghighatdoost F, Hariri M. Does alpha-lipoic acid affect lipid profile? A meta-analysis and systematic review on randomized controlled trials. Eur J Pharmacol. 2019;847:1-10. PMID: 30633888.
- Namazi N, Larijani B, Azadbakht L. Alpha-lipoic acid supplement in obesity treatment: A systematic review and meta-analysis of clinical trials. Clin Nutr. 2018;37(2):419-428. PMID: 28629898.
- Capece U, Moffa S, Improta I, et al. Alpha-Lipoic Acid and Glucose Metabolism: A Comprehensive Update on Biochemical and Therapeutic Features. Nutrients. 2022;15(1):18. PMID: 36615676.
- Gullo D, Evans JL, Sortino G, Goldfine ID, Vigneri R. Insulin autoimmune syndrome (Hirata Disease) in European Caucasians taking α-lipoic acid. Clin Endocrinol (Oxf). 2014;81(2):204-209. PMID: 24111525.
- Li Z, Su Y, Yi D, Wu C, Fang W, Wang C. Analysis of the clinical characteristics of insulin autoimmune syndrome induced by alpha-lipoic acid. J Clin Pharm Ther. 2021;46(5):1295-1300. PMID: 33821530.
- Yao D, Jiang J, Zhou Q, et al. HLA Alleles Associate with Insulin Autoimmune Syndrome. Diabetes Metab Syndr Obes. 2024. PMID: 39309309.