Also known as: ALA, R-ALA, R-lipoic acid, Thioctic acid, Na-R-ALA
FoundationalGood evidence
A sulphur compound that works as both a mitochondrial cofactor and an antioxidant, and is unusual in being soluble in both water and fat. The R and S forms are not equivalent, which most labels quietly avoid mentioning.
Typical dose
300.0–600.0 mg per day
Empty stomach, 30 minutes before food; separate from biotin
What it is
Alpha lipoic acid is a sulphur-containing compound made in small amounts by the body and found in trace quantities in spinach, broccoli and organ meats. Dietary amounts are far below supplemental doses.
It is often described as the universal antioxidant because it is soluble in both water and fat, meaning it operates in environments that vitamin C and vitamin E cannot both reach.
The form question is the practical one. R-lipoic acid is the naturally occurring, biologically active form. S-lipoic acid is a by-product of chemical synthesis and is largely inactive. Most cheap products are a 50:50 racemic mixture, which means half of what you pay for does little. R-ALA products cost more but deliver more active compound per milligram, and the sodium-stabilised version addresses R-ALA's poor stability.
How it works
In its natural role, lipoic acid is a cofactor for mitochondrial enzyme complexes that feed carbohydrate and amino acid breakdown into the citric acid cycle. That role is filled by the R form specifically.
As a supplement, free lipoic acid acts as an antioxidant and, more interestingly, regenerates other antioxidants including vitamin C, vitamin E and glutathione. That recycling role may matter more than its direct activity.
It also activates AMPK and influences glucose uptake, which is the basis for the research on blood sugar handling and much of its use in body composition formulas.
What the evidence shows
Blood sugar markers are the best-studied area, with meta-analyses reporting improvements in fasting glucose and insulin sensitivity measures, more evident in people whose readings were abnormal to begin with.
There is also reasonable evidence for effects on nerve-related sensations such as tingling and burning, studied over several decades, largely in supervised settings and at higher doses than most supplements provide.
Body composition findings are modest, with meta-analyses reporting small reductions in weight, generally under a kilogram. As with several ingredients in this index, that is statistically detectable and practically marginal.
Dosing
Typical range is 300-600 mg daily of racemic ALA. R-ALA is used at roughly half that, around 150-300 mg, since it contains only the active form.
Take on an empty stomach, 30 minutes before a meal or two hours after. Food substantially reduces absorption, and this makes more difference than most people realise.
Split doses above 300 mg. Because it affects glucose uptake, be aware it can lower blood sugar, and take care if yours is being managed. One genuine interaction: lipoic acid competes with biotin, so if you take both, separate them rather than dosing together.
At a glance
Common forms
Racemic alpha lipoic acid, R-lipoic acid (R-ALA), Sodium R-lipoate (Na-R-ALA), Within body composition formulas
Half-life / duration
Short plasma half-life; divided dosing is standard
Timing
Empty stomach, 30 minutes before food; separate from biotin
Competition status
Permitted — not on the WADA Prohibited List
Category
Foundational
Safety and side effects
Generally well tolerated. Digestive upset, nausea and skin rash are the most commonly reported effects. Some people notice a sulphurous smell to their urine, which is harmless.
Because it lowers blood sugar, take care if yours is being managed, and be aware of the possibility of it dropping lower than expected.
Lipoic acid competes with biotin for the same transporters, so sustained high-dose use alongside biotin is worth separating. Speak to your doctor before use if you take regular medication, and note that it may affect thyroid hormone handling.
Who should avoid it
Take care if your blood sugar is being managed. Separate from biotin, since the two compete for the same transporters. Speak to your doctor before use if you take regular medication or if your thyroid function is being monitored. Not established at supplemental doses in pregnancy or breastfeeding.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
