R-Alpha Lipoic Acid UK — R vs S, Racemic ALA & Na-R-ALA Explained
R-alpha lipoic acid, and why the letter matters.
Alpha lipoic acid comes in two mirror-image forms. Most supplements sell you both — and only one of them occurs in nature. Here is how to read an ALA label, and why a 600mg capsule may contain 300mg of what you actually wanted.
R-alpha lipoic acid UK — summary
Alpha lipoic acid, also called thioctic acid, is a sulphur-containing compound produced in small amounts by the body and found in foods including spinach, broccoli and offal. It is a chiral molecule, existing as two mirror-image enantiomers: R-alpha lipoic acid, the naturally occurring form, and S-alpha lipoic acid, which does not occur in nature and is produced as a by-product of chemical synthesis. Most alpha lipoic acid supplements are racemic, a roughly 50/50 mixture of both forms, so a 600mg racemic capsule supplies approximately 300mg of the R form. R-alpha lipoic acid supplements supply only the R form. Free R-alpha lipoic acid is unstable and sensitive to heat and moisture, so a stabilised sodium salt known as Na-R-ALA or sodium R-lipoate is often used instead. When comparing products, check whether the label says R-ALA, S-ALA or simply alpha lipoic acid, since an unqualified label usually indicates a racemic mixture. Vitality Supplements sells R-Alpha Lipoic Acid at 300mg per serving in 60 vegan capsules for GBP 17.99, manufactured in the United Kingdom and tested every batch by an ISO/IEC 17025-accredited laboratory. There are no authorised UK or EU health claims on alpha lipoic acid.
What alpha lipoic acid is.
Alpha lipoic acid — ALA, also called thioctic acid — is a sulphur-containing compound made in small quantities by the body and present in foods such as spinach, broccoli, tomatoes and offal. Dietary amounts are very small compared with a supplement serving.
One property makes it unusual among supplement ingredients: it is soluble in both water and fat. Most compounds are comfortably one or the other, which limits where in the body they can travel.
Do not confuse it with the other ALA. Alpha-linolenic acid is an omega-3 fatty acid found in flaxseed and walnuts — a completely different compound that unhelpfully shares the same abbreviation. If a product mentions ALA alongside omega oils, it is almost certainly the fatty acid, not this.
R and S: two mirror images.
Alpha lipoic acid is chiral — like your hands, it exists in two forms that are mirror images of each other and cannot be superimposed. Chemists label them R and S.
R-alpha lipoic acid
This is the form that occurs in nature. It is what your body synthesises, what is present in spinach and broccoli, and what enzymes in the body are built to recognise.
S-alpha lipoic acid
This form does not occur in nature at all. It is a by-product of chemical synthesis — when ALA is manufactured in a laboratory, the process produces both mirror images in roughly equal quantity, and separating them costs money.
So S-ALA is not in your capsule because someone decided it should be. It is there because taking it out is expensive.
Why 600mg might mean 300mg.
A mixture of both mirror images in equal parts is called racemic. The great majority of alpha lipoic acid supplements sold are racemic, and this is the single most useful thing to understand before comparing products.
If a label simply says "Alpha Lipoic Acid 600mg" with no R or S qualifier, it is almost certainly racemic — roughly 300mg R and 300mg S. If a label says "R-Alpha Lipoic Acid 300mg", all 300mg is the R form.
Those two products contain the same amount of R-ALA. The first simply carries 300mg of the synthetic mirror image alongside it, and looks like a bigger number on the front of the bottle.
This is why ALA prices look so inconsistent. A cheap 600mg racemic capsule and a pricier 300mg R-ALA capsule may be closer in real terms than the labels suggest. It is the same reasoning that makes berberine forms and quercetin preparations impossible to compare on milligrams alone.
What Na-R-ALA means.
There is a catch with pure R-ALA: in its free acid form it is unstable. It is sensitive to heat and moisture and can polymerise — clump together — which is unhelpful in a capsule sitting in a warehouse.
The usual solution is a stabilised sodium salt, labelled Na-R-ALA or sodium R-lipoate. It is more stable at room temperature and easier to handle in manufacturing.
If you see Na-R-ALA on a label, that is a stability measure, not a different active. Worth noting that the sodium contributes to the stated weight, so as ever, check what figure the number refers to.
The three things on a shelf.
What you will actually encounter when shopping for alpha lipoic acid, and how the numbers translate.
| Label says | What it contains | R-ALA in a 600mg serving | Notes |
|---|---|---|---|
| Alpha Lipoic Acidno R or S stated | Racemic — roughly 50% R, 50% S | ~300mg | The most common and least expensive option |
| R-Alpha Lipoic Acid★ The natural form only | R form only | 600mg | Costs more to produce; free acid form is less stable |
| Na-R-ALA / sodium R-lipoate | R form as a stabilised sodium salt | Below 600mg — sodium counts toward the weight | More stable at room temperature |
Figures illustrate how label weights translate between preparations. Always read the ingredient panel rather than the front of the pack.
300mg of R-alpha lipoic acid per serving — the R form only, no S-ALA making up the weight. 60 vegan capsules, manufactured in the UK, every batch tested by an ISO/IEC 17025-accredited laboratory.
The terms, defined.
Alpha lipoic acid questions.
Go deeper.
Written by the Vitality Supplements Editorial Team. We make one of the products described here, and we say so plainly. The comparison above is written so you can interpret any brand's alpha lipoic acid label, not only ours — the racemic maths applies universally. We describe composition, chemistry and labelling only. There are no authorised UK or EU health claims on alpha lipoic acid, so we make none. See our editorial standards.
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you are pregnant, breastfeeding, taking medication or under medical care, consult a healthcare professional before use. This page is general information, not medical advice, and is not intended to diagnose, treat or prevent any condition. There are no authorised UK or EU health claims on alpha lipoic acid, and no medicinal or disease claims are made here. Prices correct at the time of publication; live pricing is shown on the product page. Every Vitality batch is independently tested by an ISO/IEC 17025-accredited laboratory. UK manufactured. See our full disclaimer.