5 Potential Benefits of Malic Acid and Side Effects to Consider

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.

Here's a list of things malic acid is used for as well as malic acid side effects, warnings and more.

Some research shows malic acid can help alleviate dry mouth. A spray containing 1 percent malic acid improved dry mouth and increased saliva flow in people who had antidepressant-induced dry mouth after two weeks of use, per a November 2012 ​Depression & Anxiety​ study.

Supplementing with malic acid may help treat calcium renal stone disease by increasing urine pH and citrate levels, according to a January 2014 ​Journal of Endourology​ paper.

Malic acid is also an alpha-hydroxy acid (AHA), which has exfoliating properties when applied to the skin. It seems to help with melasma, a pigmentation disorder that causes dark patches on the skin, including the face, per a January 2013 study in the ​Journal of Drugs in Dermatology​.

Malic acid on its own hasn't been the object of much scientific interest. But, because malic acid is a natural product of your body's energy cycles, it sometimes crops up as part of compounds being evaluated as treatments for fibromyalgia and improving sports performance.

The evidence of malic acid's efficacy on all fronts is, at best, uncertain. Of particular note, one meta-analysis in the May 2019 issue of ​Medwave​ concluded that a combination of magnesium and malic acid made little or no difference in the pain and depressive symptoms of people with fibromyalgia.

But, in a Huntington College of Health Sciences summary of research, people with fibromyalgia did show rapid improvement in pain levels after 48 hours of supplementation with 1,200 to 2,400 milligrams of malic acid plus magnesium and then lost that improvement after they stopped taking the malic acid.

What's more, an older May 1995 pilot study in the ​Journal of Rheumatology​ found that supplementing with 200 milligrams of malic acid and 50 milligrams of magnesium daily for six months decreased the symptoms of pain and tenderness in people with fibromyalgia.

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, increasing its levels may also improve your energy or sports performance, per the National Institutes of Health.

But, despite malic acid's use for this purpose, there is no conclusive proof that it's effective. Of particular note, a small study of nine people 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 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 people who are more adapted to exercise might show different responses.

Ultimately, more research is definitely needed to prove or disprove any of malic acid's purported benefits.

The dosages used in studies and supplements of malic acid range from 200 milligrams to 2,800 milligrams per day. Malic acid is often paired with magnesium because more pronounced improvements in fibromyalgia and chronic fatigue syndrome are seen with this combination.

There is no known toxic level of malic acid, but it can result in loose stools for certain individuals at higher dosages.

Many people wonder if malic acid is bad for you. You'll find it naturally present in many fruits and vegetables you eat, including apples, apricots, mangoes, strawberries, pineapples, grapes, lettuce, onions, celery, cauliflower, cabbage, Brussels sprouts and more, and it's not likely that you'll eat too much malic acid.

Because malic acid is a naturally occurring compound in common foods, it's generally considered safe — but in some cases, it can cause side effects, particularly for the stomach and digestive tract.

Acids can irritate the mouth, throat or stomach, especially in people who are more sensitive. You may need to avoid foods and beverages that have malic acid for a few days if you have diarrhea or an upset stomach because acids in foods may cause cramps and gas and prolong diarrhea, according to Virginia Tech.

If you're diagnosed with a gastrointestinal condition, such as IBS, gastritis or acid reflux, foods and beverages with malic acid may be off the menu. Eating foods with acid can cause the stomach to produce more gastric acid, which can then irritate damage that already exists in the digestive tract, according to Hopkins Medicine.

Other possible side effects of malic acid, per a November 2000 ​International Journal of Toxicology​ safety report, include:

• skin irritation
• loose stools or diarrhea
• nausea
• indigestion