Malic acid — or in its ionized form, malate — is an organic compound that occurs naturally in a variety of fruits and vegetables. It can also be synthesized in the body as part of aerobic and anaerobic energy cycles.
Malic Acid Safety
You'll find malic acid naturally present in numerous fruits and vegetables, including apples, apricots, mangoes, strawberries, pineapples, grapes, lettuce, onions, celery, cauliflower, cabbage, Brussels sprouts and more.
Because malic acid is a naturally occurring compound in common foods, it's generally considered safe for human consumption — and as the Toxicology Data Network notes, it's often added to processed foods, including baked goods, frozen dairy, soft candy and nonalcoholic beverages.
However, the TDN also notes a scattering of adverse complaints from a test of malic acid and magnesium in the treatment of fibromyalgia. The complaints included nausea, dyspepsia and diarrhea, and it's not clear if they were ever tied directly to the malic acid and magnesium supplements or not.
If you're exposed to malic acid in your work environment, your concerns are different than someone who takes it as a supplement. The Toxicology Data Network classifies malic acid as strongly irritating to the skin, and especially an irritant to the eyes. It also considers inhalation of malic acid to present a risk.
Malic Acid for Fibromyalgia
Malic acid on its own hasn't been the object of much scientific interest. However, because malic acid is a natural intermediate product of your body's energy cycles, it sometimes crops up as part of compounds being evaluated as treatments for fibromyalgia or to boost sports performance.
However, the evidence of malic acid's efficacy on all fronts is, at best, uncertain. Of particular note, a data analysis published in the May 2019 issue of Medwave, concludes that a combination of magnesium and malic acid made little or no difference in the pain and depressive symptoms of patients with fibromyalgia.
However, not all studies confirm that. As the Huntington College of Health Sciences notes in another summary of research, fibromyalgia patients have shown rapid improvement in pain levels after 48 hours of supplementation with 1,200 to 2,400 mg of malic acid plus magnesium, and then lost that improvement after they stopped taking the malic acid.
Malic Acid for Energy
As noted by National Institutes of Health, malic acid is often combined with citrulline as an athletic supplement — on the theory that because malate is an intermediate product of your body's energy cycles, boosting its levels may also boost your energy levels or sports performance.
However, despite malic acid's ubiquity for this purpose, there is no conclusive proof that it's effective. Of particular note, a small study of nine subjects, published in the October 2017 issue of Nutrients, showed that taking citrulline malate — a mix of malic acid and citrulline — did not improve muscle recovery after resistance exercise.
There are, of course, a number of caveats to consider in that study, not least the very small sample size and the fact that the subjects weren't accustomed to exercise; it's possible that bodies that are better adapted to exercise might show different responses.
Ultimately, more research is definitely needed to prove or disprove any of malic acid's purported benefits. And in the meantime, if you're taking malic acid for a medical condition such as fibromyalgia, always talk to your doctor first. In the absence of clear guidelines for dosage, a doctor is your first line of defense in identifying possible contraindications and drug interactions for this and any other supplements.
- Toxicology Data Network: "Malic Acid"
- Medwave: "Magnesium and Malic Acid Supplement for Fibromyalgia"
- Huntington College of Health Sciences: "Chronic Fatigue Syndrome and Fibromyalgia"
- Nutrients: "Citrulline Malate Does Not Improve Muscle Recovery After Resistance Exercise in Untrained Young Adult Men"
- National Institutes of Health: "Dietary Supplements for Exercise and Athletic Performance"