Alpha-lipoic acid
Alpha-lipoic acid is a sulfur compound the body makes to help its enzymes turn glucose into energy. Food holds only traces; supplements give far more, and are studied mainly for diabetic nerve pain.
2 sulfur atoms in a small ring, the part that does its chemistry
Not the omega-3 alpha-linolenic acid shares the short name ALA
Daily need · none set; the body makes its own
- Made in Mitochondria from a fatty acid
- Two forms R and S the body makes only R
- Studied for Nerve pain in diabetes; short-term relief
- Watch with Diabetes medicines blood sugar may drop further
Sources: National Center for Complementary and Integrative Health (NCCIH), biochemistry textbooks, systematic reviews of trials. Not medical advice.
Alpha-Lipoic Acid in Food
In food, alpha-lipoic acid is locked onto protein (as lipoyllysine) in tissues that burn a lot of energy. The amounts are tiny, so diet supplies little; supplements are the main source of free alpha-lipoic acid. The Caltide food library does not measure it.
- Organ meatskidney, heart and liver have the most
- Green vegetablesspinach and broccoli are the richest plant sources
- Other vegetablestomatoes, peas and Brussels sprouts, in smaller amounts
What Is Alpha-Lipoic Acid?
Supplement labels and articles shorten two unrelated compounds to ALA. Alpha-lipoic acid, this page, is a sulfur compound that works inside enzymes. Alpha-linolenic acid is the omega-3 fat in flaxseed, chia and walnuts, a nutrient you need from food. A capsule labeled only ALA could be either, so read the full name.
What Alpha-Lipoic Acid Does in Cells
The body builds alpha-lipoic acid in the mitochondria from octanoic acid, a short fatty acid, and clips it onto a few large enzymes. There it is a cofactor, a working part those enzymes cannot run without. The best known is pyruvate dehydrogenase, the enzyme that lets the breakdown products of glucose enter the energy cycle. Without lipoic acid, glucose cannot be fully burned for fuel.
Free alpha-lipoic acid, the form in supplements, acts differently. In lab studies, it and its reduced form, dihydrolipoic acid, neutralize reactive oxygen molecules, and it dissolves in both water and fat, so it works in the watery inside of cells and in membranes. In the same studies it helps recycle other antioxidants such as vitamin C, vitamin E and glutathione, though how much of this happens in the body is unclear. That is why it is often grouped with CoQ10 and NAC.
What Human Studies Show About Alpha-Lipoic Acid
Diabetic nerve pain is where the evidence is strongest, and it is still limited. In Germany it is an approved medicine for it. Trials that gave it by IV for about three weeks found less burning, pain and numbness in the feet; trials of capsules by mouth have been less consistent, and none has shown that it repairs nerve damage over the long term.
For weight loss, reviews found a very small effect at most. For blood sugar control, results are small and mixed. Claims about aging, skin and memory rest mostly on lab and animal studies.
Common Alpha-Lipoic Acid Mistakes
Buying the wrong ALA. An omega-3 capsule and an alpha-lipoic acid capsule can both say ALA on the front.
Expecting food to match a capsule. Even organ meats and spinach give only traces, bound to protein, not the free form studied in trials.
Ignoring blood sugar. Added to insulin or diabetes pills, it can push blood sugar lower than expected.
Alpha-Lipoic Acid Supplements
Supplements are the only source of free alpha-lipoic acid in amounts like those studied. Labels differ mainly in which mirror-image form they contain.
Alpha-Lipoic Acid Supplement Forms
- Alpha-lipoic acid (R/S)a 50:50 mix of both forms, the kind used in most trials
- R-lipoic acidthe natural form only; reaches higher blood levels, but better results in people are not proven
- Thioctic acidanother name for alpha-lipoic acid, common on medicines in Europe
Alpha-Lipoic Acid Safety
- Side effectsusually mild: nausea, heartburn, skin rash
- Diabetes medicinesmay lower blood sugar further; check levels
- Rare: low blood sugar from antibodiesa rare reaction called insulin autoimmune syndrome, reported mostly in people of East Asian descent with a certain gene type
- Pregnancynot enough is known about safety
Caltide does not total alpha-lipoic acid yet. Sources: NCCIH, reviews of trials. Ask a doctor or pharmacist before combining a supplement with a medicine.
Alpha-lipoic Acid Sources and References
The figures and claims on this page are checked against these sources.
- NCCIH: Diabetes and Dietary Supplements: What You Need To Know
- Mijnhout and others: Alpha Lipoic Acid for Symptomatic Peripheral Neuropathy in Patients with Diabetes, a meta-analysis of randomized controlled trials (2012)
- American Family Physician: Alpha-Lipoic Acid for Treatment of Diabetic Peripheral Neuropathy (2016)
Questions About Alpha-lipoic Acid
Alpha-lipoic acid (lipoic acid, thioctic acid) is a sulfur-containing compound the body makes in small amounts. Bound to enzymes in the mitochondria, it helps turn glucose into energy. The free form in supplements acts as an antioxidant in lab studies, though how much it does so in the body is unclear.
No. Both are shortened to ALA, but alpha-linolenic acid is a plant omega-3 fat from flaxseed and walnuts, while alpha-lipoic acid is a sulfur compound with a different job. Check the full name on any label that says ALA.
Organ meats such as kidney, heart and liver, and vegetables such as spinach, broccoli and tomatoes. The amounts are tiny and bound to protein, far below what supplements give.
It may ease symptoms for a while. Trials of alpha-lipoic acid given by IV for about three weeks found less burning, pain and numbness from diabetic neuropathy. Results with capsules by mouth are less consistent, and long-term benefit is not proven.
The natural form. Alpha-lipoic acid comes in two mirror-image forms, R and S; the body makes only R. Most supplements are a 50:50 mix of both, and some sell R alone. Whether R alone works better in people has not been settled.
It may, slightly. That matters most for people on insulin or diabetes pills, whose blood sugar could drop too low. Check with your doctor and watch your levels if you add it.
Only a little, if at all. Reviews of trials found a very small extra weight loss compared with placebo, too small to matter for most people.
Food lowers how much of it is absorbed, so it is often taken before a meal. If it upsets your stomach, taking it with food is a reasonable trade.
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