Alpha-lipoic acid is a supplement with one useful result behind it: it eases the burning, stabbing and numb feeling of diabetic nerve damage. Given by drip at 600 mg a day for about three weeks it lowered neuropathy symptom scores by roughly a quarter more than placebo across four trials, and a 600 mg daily capsule cut those symptoms about half over five weeks in the SYDNEY 2 trial. Taken as a capsule for months to years its effect on the underlying nerve damage is smaller, and a four-year trial found no change in its main nerve measure.
Beyond the nerves the picture thins out: pooled trials show a small weight loss, about a kilogram more than placebo over a few months, and modest improvements in blood sugar in people with metabolic disease, though those trials are small and varied. The broad antioxidant and anti-aging promises on the label rest mostly on cell and animal work. The main safety point is real: alpha-lipoic acid can push blood sugar low, so anyone taking insulin or a sulfonylurea needs to watch for hypoglycemia, and it can rarely trigger an autoimmune form of low blood sugar.
Findings & Outcomes
What It Is
Alpha-lipoic acid, sometimes labeled thioctic acid, is a small sulfur-containing molecule your body makes in its own mitochondria, where it works as a cofactor that helps the enzyme pyruvate dehydrogenase turn food into energy. That is its day job inside every cell. The reason it sits on supplement shelves is a second property: taken by mouth in far larger amounts than the body makes, it is redox-active, meaning it can hand off and pick up electrons, and in the test tube it regenerates vitamins C and E and helps restore glutathione, the cell's main internal antioxidant.
Your body already makes all the alpha-lipoic acid it needs for the enzyme role, and the traces in food (organ meats, red meat, some vegetables) are small. So a supplement is not correcting a deficiency. It is a pharmacological dose, typically 600 mg a day, taken to see whether the extra changes anything measurable. Most of the human evidence that it does comes from one place: diabetic nerve damage.
What It Does
The clearest result is for diabetic peripheral neuropathy, the burning, stabbing, tingling and numbness in the feet and legs that comes with long-standing diabetes. Two forms have been tested. An intravenous course of 600 mg a day for about three weeks lowers the symptom score in a way that shows up across pooled trials, and a 600 mg daily capsule lowered symptoms over five weeks in the SYDNEY 2 trial. Over the long haul the effect on the nerve damage itself is smaller: a four-year trial of the daily capsule missed its main nerve measure while nudging some secondary ones.
Away from the nerves, the evidence is thinner and points to smaller effects. Pooled weight-loss trials show alpha-lipoic acid takes off about a kilogram more than placebo over a few months, a small difference. In people with diabetes or metabolic syndrome, meta-analysis finds modest improvements in fasting glucose and HbA1c, though the trials behind that are small and vary a lot in quality. The wider antioxidant and anti-aging story that sells the supplement is mostly cell and animal work, and it has not been carried into human trials of aging, cognition or longevity. Each card below grades one of these at the strength of its own evidence.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Pain
Oral 600 mg a day cut diabetic nerve symptoms about 51% over 5 weeks (SYDNEY 2)
Taking a 600 mg alpha-lipoic acid capsule daily for five weeks cut the burning, stabbing and numb feeling of diabetic nerve damage roughly in half, clearly more than a dummy pill, and taking more than 600 mg did not add any benefit.
The SYDNEY 2 trial randomized 181 diabetic patients in Russia and Israel to oral alpha-lipoic acid at 600, 1,200 or 1,800 mg a day, or placebo, for 5 weeks after a 1-week placebo run-in. The primary outcome was change in the Total Symptom Score. Mean TSS fell by 4.9 points (51%) at 600 mg, 4.5 (48%) at 1,200 mg and 4.7 (52%) at 1,800 mg, versus 2.9 points (32%) on placebo (all P < 0.05 vs placebo), with responder rates of 62%, 50%, 56% and 26% respectively. Stabbing and burning pain, the Neuropathy Symptoms and Change score, and patients' global assessment of efficacy also favored all three doses; the Neuropathy Impairment Score was only numerically reduced. Higher doses brought a dose-dependent rise in nausea, vomiting and vertigo, so the authors concluded 600 mg once daily gives the best risk-to-benefit ratio.
Who this may not transfer to:Both sexes were enrolled; the trial did not break the symptom results out by sex.
This is the practical at-home form and dose for diabetic nerve symptoms. It relieves the symptom over weeks; it is not shown to repair the nerve, and it sits on top of blood-sugar control, not in place of it. Anyone on insulin or a sulfonylurea should read the hypoglycemia caution before starting.
The study · 1
Ziegler et al., Oral treatment with alpha-lipoic acid improves symptomatic diabetic polyneuropathy: the SYDNEY 2 trial · Diabetes Care 2006;29(11):2365-2370
Intravenous 600 mg a day for 3 weeks lowered nerve symptoms about 24% more than placebo
Adding up four trials, a three-week course of alpha-lipoic acid given by a drip lowered diabetic nerve symptoms about a quarter more than a dummy infusion, with just over half the treated patients clearly responding versus about a third on placebo. This short intravenous course is the most consistent evidence for the supplement.
This meta-analysis searched the manufacturer's (VIATRIS/MEDA) trial database for randomized, double-masked, placebo-controlled, parallel-group trials of 600 mg a day intravenous alpha-lipoic acid for 3 weeks in diabetic polyneuropathy scored by the Total Symptom Score. Four trials (ALADIN I, ALADIN III, SYDNEY, NATHAN II) totaling 1,258 patients (716 on alpha-lipoic acid, 542 on placebo) met the criteria. After 3 weeks the relative difference favoring alpha-lipoic acid was 24.1% for TSS (95% CI 13.5 to 33.4) and 16.0% for the Neuropathy Impairment Score of the lower limbs. Responder rates were 52.7% versus 36.9% (P < 0.05). The improvement grew day by day and became detectable after 8 days.
Who this may not transfer to:Both sexes were included across the pooled trials, which did not report the symptom effect separately by sex.
The intravenous route carries the most consistent signal but is a clinic procedure, not a self-administered option, and the effect is on symptoms over weeks rather than on the course of the nerve disease. That the trials all came from a single manufacturer's database is worth weighing.
The study · 1
Ziegler et al., Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: a meta-analysis · Diabet Med 2004;21(2):114-121
Over 4 years, the daily capsule did not change the main nerve measure (NATHAN 1)
Over four years the daily capsule did not beat a dummy pill on its main, objective measure of nerve function, though it did a little better on some secondary scores. So it eases symptoms in the short term but is not shown to slow the underlying nerve damage over years.
The NATHAN 1 trial randomized 460 diabetic patients with mild-to-moderate distal symmetric polyneuropathy to 600 mg a day of oral alpha-lipoic acid (n = 233) or placebo (n = 227) for 4 years. The primary composite endpoint combined the Neuropathy Impairment Score of the lower limbs with seven nerve-conduction and sensory tests, and the change from baseline did not differ between groups (P = 0.105). Change was significantly better with alpha-lipoic acid for the broader Neuropathy Impairment Score (P = 0.028), NIS-LL (P = 0.05) and a muscle-weakness subscore, and more patients showed a clinically meaningful improvement while fewer progressed. Because the placebo group's primary score did not deteriorate significantly, the trial could not demonstrate the secondary prevention it was designed to test. Serious adverse events were higher on alpha-lipoic acid (38.1% vs 28.0%).
Who this may not transfer to:Both sexes were enrolled under the trial's contraception and postmenopausal criteria; results were not reported separately by sex.
This is the honest limit on the popular claim: relieving symptoms over weeks is not the same as halting nerve damage over years, and on the harder, objective endpoint the daily capsule did not separate from placebo. Read it alongside the short-term symptom benefit, not instead of it.
The study · 1
Ziegler et al., Efficacy and safety of antioxidant treatment with alpha-lipoic acid over 4 years in diabetic polyneuropathy: the NATHAN 1 trial · Diabetes Care 2011;34(9):2054-2060
Weight And Fat Loss
About 1.3 kg more weight loss than placebo over a few months
Adding up the trials, people taking alpha-lipoic acid lost about 1.3 kg more than those on a dummy pill over a few months, a real but small difference. It is not a weight-loss drug, and it works best as a minor add-on to diet and activity.
This meta-analysis identified 10 randomized, double-blind, placebo-controlled studies (11 eligible studies, 12 treatment arms; 534 people on alpha-lipoic acid, 413 on placebo) across populations with diabetes, metabolic syndrome, rheumatoid arthritis, non-alcoholic fatty liver disease and dedicated weight-loss cohorts. Alpha-lipoic acid was associated with 1.27 kg greater weight loss (95% CI 0.25 to 2.29) and a 0.43 kg/m2 lower BMI (95% CI 0.03 to 0.82) than placebo. Doses spanned 300 to 1,800 mg a day and durations 8 to 52 weeks; meta-regression found no significant effect of dose, and study duration affected the BMI change but not the weight change. The authors describe the effect as small, short-term and in need of longer trials.
Who this may not transfer to:Trials enrolled both sexes across varied conditions; the pooled analysis did not report the weight effect separately by sex.
Expect little. A kilogram over a few months is a minor add-on, not a reason to expect meaningful weight loss on its own, and the trials were short. Put the effort into the diet, movement and sleep that move weight further.
The study · 1
Kucukgoncu et al., Alpha-lipoic acid (ALA) as a supplementation for weight loss: results from a meta-analysis of randomized controlled trials · Obes Rev 2017;18(5):594-601
How it works
A mitochondrial energy cofactor that also acts as a redox antioxidant
Your body makes alpha-lipoic acid to help its cells produce energy. The supplement doses add a second job: acting as an antioxidant that recharges vitamins C and E and boosts the cell's own antioxidant, glutathione. Most of that antioxidant story is shown in cells and animals rather than in people.
Alpha-lipoic acid (1,2-dithiolane-3-pentanoic acid) is made in the mitochondrion from octanoic acid and, in its protein-bound R form, is a required cofactor for mitochondrial alpha-ketoacid dehydrogenases including pyruvate dehydrogenase, placing it at the center of energy metabolism. Oral supplements deliver mostly unbound alpha-lipoic acid, which is absorbed variably (roughly 20 to 40% of a dose), accumulates transiently in liver, heart and skeletal muscle, and is rapidly metabolized and excreted. As a redox couple with dihydrolipoic acid it scavenges reactive species, regenerates the oxidized forms of vitamins C and E, restores glutathione, chelates metals, and has been shown to activate Nrf2-driven detoxification and repress NF-kappa-B signaling in laboratory systems. The one condition where these properties have translated into defined human benefit is diabetic polyneuropathy; the broader anti-aging and vascular claims rest largely on preclinical work.
The study · 1
Shay et al., Alpha-lipoic acid as a dietary supplement: molecular mechanisms and therapeutic potential · Biochim Biophys Acta 2009;1790(10):1149-1160
Blood Sugar
Modest improvements in fasting glucose and HbA1c, from small varied trials
Adding up 24 trials in people with diabetes or metabolic problems, alpha-lipoic acid improved fasting blood sugar and HbA1c somewhat, but the trials were small and varied a lot, so this is a modest and uncertain effect, not a substitute for diabetes treatment.
This systematic review and meta-analysis pooled 24 randomized controlled trials of alpha-lipoic acid in patients with metabolic diseases (type 2 diabetes, metabolic syndrome and related conditions). Reported as standardized mean differences, alpha-lipoic acid significantly reduced fasting glucose (SMD -0.54; 95% CI -0.89 to -0.19; P = 0.003), insulin (SMD -1.01), HOMA-IR (SMD -0.76), HbA1c (SMD -1.22; 95% CI -2.01 to -0.44), triglycerides, total cholesterol and LDL cholesterol, with no effect on HDL. The confidence intervals are wide and heterogeneity between studies was high, and the individual trials were small, so the size of the real-world effect is uncertain. Alpha-lipoic acid is not established as a standalone glucose-lowering therapy.
Who this may not transfer to:The pooled trials enrolled both sexes and did not report glycemic effects separately by sex.
Treat this as a minor, uncertain add-on rather than a diabetes treatment. The more clinically relevant fact is the flip side: because it can lower glucose, combining it with insulin or a sulfonylurea can cause hypoglycemia, so monitoring matters when starting.
The study · 1
Akbari 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;87:56-69
The Nerve-Pain Evidence
For diabetic neuropathy, the strength of the evidence tracks the route and the timescale, and the picture is best read as three separate statements rather than one headline.
The most consistent signal is the short intravenous course. A meta-analysis of four randomized trials, totaling 1,258 people, gave 600 mg a day by drip for three weeks and found the Total Symptom Score fell about 24% more than with placebo, with just over half the treated patients counting as responders against about a third on placebo. Symptoms began to separate from placebo after about eight days. A daily capsule was then tested head to head against placebo in SYDNEY 2: at 600 mg a day for five weeks the symptom score dropped about 51%, against 32% on placebo, and higher doses of 1,200 and 1,800 mg did no better while causing more nausea.
The third statement is where the popular version overreaches. Easing symptoms over weeks is not the same as slowing the nerve damage over years, and when that longer question was put to the four-year NATHAN 1 trial of the daily 600 mg capsule, the main combined measure of nerve function did not separate from placebo. Some secondary impairment scores improved and fewer people worsened, which is a finding on its own, but the primary endpoint was null. So the fair read is that alpha-lipoic acid relieves neuropathic symptoms, most reliably as a short intravenous course, and that it is not established as a way to reverse or halt the underlying nerve damage. Much of this trial base was run from a single manufacturer's database, which is worth holding in mind when weighing it.
For diabetic nerve symptoms the intravenous course has the most consistent record and the 600 mg capsule is the practical at-home form, weighed against the blood-sugar cautions below for anyone on glucose-lowering medication.
How It Works
Inside the mitochondria alpha-lipoic acid is bound to enzymes as a cofactor, part of the machinery that pulls energy out of glucose. The supplement story is about the unbound molecule that circulates after a large oral dose. It and its reduced partner, dihydrolipoic acid, form a redox couple that can neutralize free radicals, regenerate the used-up forms of vitamins C and E, and raise glutathione, and it can loosely bind metals. In diabetic nerves, where high blood sugar drives oxidative stress, that antioxidant action is the proposed reason symptoms ease. A mechanism explains what might happen; whether people actually feel better has to be measured, which is what the neuropathy trials did.
Anatomy of the Practice
1As a cell's own energy cofactor
The body synthesizes alpha-lipoic acid in the mitochondria, where it is bound to pyruvate dehydrogenase and related enzymes that convert food into usable energy. This role is fully covered by what the body makes, so a supplement is not topping up a shortage; it is adding a pharmacological amount for a different, redox effect.
2As a circulating antioxidant, at supplement doses
A 600 mg oral dose puts unbound alpha-lipoic acid into the blood briefly. There it and its reduced form act as a redox couple: they mop up free radicals, regenerate spent vitamins C and E, and help restore glutathione. Most of this is shown in cell and animal work, and the effects appear at low concentrations.
3In the diabetic nerve
High blood sugar raises oxidative stress in peripheral nerves, and this is the setting where alpha-lipoic acid has been tested most and helped most. Lowering that stress is the proposed route by which burning and tingling ease. Relieving the symptom is a different result from repairing the nerve, which is where the four-year trial came up short.
Ways to Do It
For most people this is a single decision: a 600 mg daily capsule, taken for diabetic nerve symptoms, with the blood-sugar cautions below in mind. The other uses are smaller and the food route matters less here than for most supplements, because the body makes its own supply.
Red meat, organ meats and some vegetables carry small amounts of alpha-lipoic acid, and your body makes the rest, so there is no deficiency to eat your way out of. For diabetic nerve pain the free groundwork that changes the disease is blood-sugar control, weight, activity and foot care; alpha-lipoic acid is an add-on to that, not a substitute.
This is the dose and form behind the at-home evidence. In SYDNEY 2, 600 mg once daily lowered neuropathic symptoms over five weeks, and going higher to 1,200 or 1,800 mg did not help more and caused more nausea. Take it on an empty stomach, since food lowers how much is absorbed. If you take insulin or a sulfonylurea, read the cautions first.
The most consistent trial signal used 600 mg a day by infusion for about three weeks. It is a clinic procedure, not something to self-arrange, and it suits someone with troublesome diabetic nerve symptoms who wants the best-evidenced version. Whether the short course is worth the cost and hassle over the capsule is a reasonable thing to weigh with the clinician giving it.
Pooled trials put the weight effect at roughly a kilogram over a few months and the blood-sugar effect at modest, from small and varied studies. It is not a weight-loss drug or a diabetes treatment on its own. If you try it for these, treat it as a minor add-on to the diet, movement and medication that do the real work.
Supplements are usually a racemic mix of the R and S forms; the R form is the one the body uses, and R-only products cost more for an uncertain extra benefit. The molecule is unstable to heat and moisture, so keep capsules cool and dry and replace an old bottle rather than push its shelf life.
Go Deeper
- Blood sugar: where a modest add-on like this sits among the diet, movement and medication that move blood sugar most.
- Berberine: another supplement taken for glucose control, and how its evidence compares.
- Magnesium: a mineral with its own diabetes and nerve-related research, useful for weighing what an add-on supplement can and cannot do.
- Type 2 diabetes: the condition most alpha-lipoic acid trials were run in, and what actually moves blood sugar and nerve risk.
The Chinese Medicine View
Chinese medicine has no concept of alpha-lipoic acid, and it would be an invention to claim otherwise. The molecule is a modern isolate, and the tradition never had it. What the tradition does have is a way of reading the condition it is most used for, and that reading carries its own cautions.
Diabetic neuropathy maps loosely onto patterns the tradition describes in long-standing "wasting and thirsting" disease: numbness and tingling read as Blood failing to nourish the channels, and burning pain often as an underlying dryness or Heat with depleted Yin. From that view the tingling-numb picture is a sign of depletion and poor nourishment of the limbs, not of an excess to be purged. A tradition-minded practitioner would treat the person and the pattern, nourishing Blood and Yin or moving Blood where it has grown static, rather than reaching for a single fixed remedy for everyone with the diagnosis.
Where the two views touch is on the idea that the same intervention does not suit everyone with the same label, and this is also where the tradition would caution. A concentrated, drying, warming agent would be read as wrong for someone whose picture is already dry or depleted, and the classical texts are wary of pushing a strong single substance at a deficiency pattern. That instinct, that the fit depends on the person and their current state, sits beside a modern reading where the benefit is real but partial and the main risk, low blood sugar, depends entirely on what else the person is taking. It is offered as a way of thinking, not a claim about the molecule.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Higher oral doses (1,200 to 1,800 mg) cause dose-related nausea without added benefit
SYDNEY 2 compared oral alpha-lipoic acid at 600, 1,200 and 1,800 mg a day against placebo for 5 weeks in 181 people with symptomatic diabetic polyneuropathy. Symptom improvement was essentially the same across the three active doses (51%, 48% and 52% Total Symptom Score reductions), but the safety analysis showed a dose-dependent rise in nausea, vomiting and vertigo as the dose increased. On this basis the trial identified 600 mg once daily as the dose with the optimum risk-to-benefit ratio, which is why later trials and practice settled on it.Ziegler et al., Oral treatment with alpha-lipoic acid improves symptomatic diabetic polyneuropathy: the SYDNEY 2 trial
Can rarely trigger insulin autoimmune syndrome (autoimmune low blood sugar)
Insulin autoimmune syndrome, or Hirata disease, is a rare cause of autoimmune hypoglycemia marked by high measured insulin and anti-insulin autoantibodies, first described in Japan in 1970. It is typically triggered by sulfhydryl-containing drugs, which stimulate insulin autoantibody production, and alpha-lipoic acid (a sulfhydryl compound) has emerged as a cause since the first reports from Japan around 2006. Two case reports from an Italian center document the temporal link, with hypoglycemia resolving after the supplement was stopped. Susceptibility is associated with specific HLA class II types (HLA-DRB1*04:06 reported more in East Asian patients and HLA-DRB1*04:03 in patients of European descent), which is why cases have been concentrated in, but are not limited to, East Asian populations.Moffa et al., Potential cause-effect relationship between insulin autoimmune syndrome and alpha lipoic acid: two case reports
Low blood sugar, especially with insulin or a sulfonylurea
This is the caution that matters most. Alpha-lipoic acid can lower blood glucose, and on top of insulin or a sulfonylurea (glipizide, glimepiride, gliclazide and the like) that can add up to hypoglycemia. If you take a glucose-lowering medication and want to try alpha-lipoic acid, monitor your blood sugar more closely at the start and have your prescriber review whether the medication dose needs adjusting. The symptoms to know are shakiness, sweating, confusion and a racing heart.
A rare autoimmune form of low blood sugar
In a small number of people alpha-lipoic acid has triggered insulin autoimmune syndrome, also called Hirata disease, where the immune system makes antibodies against insulin and causes episodes of severe low blood sugar unrelated to any diabetes medication. It is linked to certain immune-gene (HLA) types and has been reported more in East Asian populations, though cases occur in people of European descent too. It is uncommon, but recurrent unexplained hypoglycemia in someone taking the supplement is a reason to stop it and get checked.
Nausea and stomach upset at higher doses
At 600 mg a day alpha-lipoic acid is generally well tolerated. In the trials, pushing the dose to 1,200 or 1,800 mg a day brought a dose-related rise in nausea, vomiting and a spinning-dizzy feeling without adding benefit, which is why 600 mg is the dose that has been used. Taking it on an empty stomach improves absorption but can be harder on the stomach for some people.
Pregnancy, breastfeeding and children
There is little trial data in pregnancy, breastfeeding or childhood, so there is no established safe dose in these groups. That absence is a reason for caution rather than a known harm, and it is a sensible thing to leave alone without a specific medical reason to use it.
If you are unwell or on several medications, talk it through first
For someone with diabetes on multiple drugs, or with thyroid, kidney or liver disease, the sensible step is to raise alpha-lipoic acid with the clinician who manages those, so the blood-sugar interaction and your own situation get weighed together before you start.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does alpha-lipoic acid help diabetic nerve pain?
Yes, for symptoms, and the effect is best shown as a short intravenous course. Pooled across four trials of about 1,258 people, 600 mg a day by drip for three weeks lowered the neuropathy symptom score roughly 24% more than placebo. A 600 mg daily capsule lowered symptoms about half over five weeks in the SYDNEY 2 trial. What it has not shown is that it reverses or halts the nerve damage itself: a four-year trial of the capsule missed its main measure of nerve function.
How much should I take, and does more help?
The dose behind the evidence is 600 mg a day, and more is not better. In SYDNEY 2, going up to 1,200 or 1,800 mg a day did not improve symptoms any further and caused more nausea, vomiting and dizziness, so 600 mg is treated as the sweet spot for benefit against side effects. It is absorbed better on an empty stomach. If you take a glucose-lowering medication, check the blood-sugar caution before starting.
Is alpha-lipoic acid good for weight loss?
Only a little. Pooling the randomized trials, people taking alpha-lipoic acid lost about 1.27 kg more than those on placebo over a few months, with a small drop in BMI. That is a real difference but a modest one, and the trials were short. It is not a weight-loss drug, and it works best thought of as a minor add-on to the eating and activity changes that do most of the work.
Does it lower blood sugar?
Modestly, and that cuts two ways. Meta-analysis in people with metabolic disease found improvements in fasting glucose and HbA1c, though from small and varied trials, so it is not established as a diabetes treatment on its own. The flip side is the main safety point: because it can push glucose down, adding it to insulin or a sulfonylurea can cause hypoglycemia. Anyone on those medications should monitor more closely at first and have the prescriber review the doses.
Is alpha-lipoic acid an anti-aging supplement?
The anti-aging and general antioxidant claims are where the marketing runs ahead of the evidence. Alpha-lipoic acid does regenerate vitamins C and E and raise glutathione, but almost all of that is shown in cells and animals, not in human trials of aging, memory or lifespan. The one area with solid human trials is diabetic nerve symptoms. For the broader promises, Western research has not measured a benefit, which is different from having measured its absence.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 8 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 16, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.