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Moderate evidenceLongevity & antioxidants

R-Alpha Lipoic Acid

The naturally occurring isomer of lipoic acid. Lipoic acid genuinely helps symptoms of diabetic neuropathy, but almost all of that evidence used the cheaper racemic mixture, not the R form specifically.

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What the science says

  • Diabetic polyneuropathy symptoms Moderate evidence

    A meta-analysis and systematic review of randomized trials found oral alpha-lipoic acid improved neuropathic symptom scores in diabetic polyneuropathy compared with placebo. Effects on objective nerve conduction were smaller and less consistent, and the trials mostly used racemic lipoic acid at 600 mg/day.

  • Advantage of the R isomer Limited evidence

    A pilot human pharmacokinetic study found R-lipoic acid reaches higher plasma concentrations than the racemic mixture, with bioavailability varying by age and sex. No clinical trial has compared the R form against racemic lipoic acid on symptoms or any health outcome, so the practical advantage is unproven.

Dosage & safety

Studied doseRacemic trials used 600 mg/day, typically on an empty stomach. R-lipoic acid products are usually dosed at 100–300 mg/day on the assumption of higher potency; stabilized sodium R-lipoate is more stable than free R-lipoic acid.
SafetyCommon effects are nausea, heartburn and rash. Lipoic acid can lower blood glucose, so people on insulin or sulfonylureas need monitoring, and it may worsen thiamine deficiency in heavy drinkers. Insulin autoimmune syndrome (a hypoglycaemia disorder) has been reported, mainly in people of Japanese and Korean ancestry carrying certain HLA types. Avoid in pregnancy and breastfeeding.

How to take it

TimingMorning, at least 30 minutes before eating.
With food?On an empty stomach — food markedly reduces absorption.
Worth knowingSplit doses above 200 mg to cut nausea, and check your glucose more often in the first few weeks if you use insulin.

Interactions

With medications

  • insulin and sulfonylureas

    Lipoic acid lowers blood glucose and can add to their effect. monitor glucose more closely and discuss dose adjustment with your doctor

  • levothyroxine

    Lipoic acid chelates metals and is taken on an empty stomach, the same window levothyroxine needs. separate by at least 4 hours

With other supplements

  • iron, zinc, magnesium and other minerals

    Lipoic acid binds metal ions and can reduce their absorption. separate by at least 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does alpha-lipoic acid help diabetic neuropathy?

Yes, moderately: a meta-analysis of randomized trials found oral alpha-lipoic acid improved neuropathic symptom scores in diabetic polyneuropathy versus placebo, with smaller effects on nerve conduction. Those trials mostly used racemic lipoic acid at 600 mg/day, not the R form.

Is R-lipoic acid better than regular alpha-lipoic acid?

R-lipoic acid reaches higher blood levels than the racemic mixture in a pilot study, but no trial has compared the two on symptoms or health outcomes. The practical advantage of R-alpha lipoic acid is unproven, so the evidence is limited.

How much R-alpha lipoic acid should I take and when?

R-lipoic acid products are usually dosed at 100–300 mg/day, while the racemic neuropathy trials used 600 mg/day. Take it in the morning at least 30 minutes before eating, since food markedly reduces absorption, and split doses above 200 mg to reduce nausea.

Can R-alpha lipoic acid lower blood sugar too much?

Yes: lipoic acid lowers blood glucose and can add to insulin or sulfonylureas, so check your glucose more often in the first few weeks and talk to your doctor about doses. Nausea, heartburn and rash are the common side effects.

Scientific references

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