“I’ve been feeling great and seem to have more energy,” wrote “Robert” on amazon.com after he started drinking apple cider vinegar every day.
If you believe what you read, vinegar—especially apple cider vinegar—can brighten your skin and remove warts, soothe your sore throat, fight cancer, prevent heartburn, banish belly fat, help your heart, lower your blood sugar, and more.
All about acetic acid
Vinegar is made in a two-step fermentation process. First, sugar (from something like fruit or rice) is fermented by yeast to produce alcohol. Next, acetic-acid bacteria ferment the alcohol to make, you guessed it, acetic acid.
Most vinegars are filtered and pasteurized, but some manufacturers leave the harmless bacteria—also called “the mother”—and label the vinegar as “raw” and “unfiltered.” This is particularly common with apple cider vinegar.
So is there anything special about apple cider vinegar? “Good marketing,” says Arizona State University professor of nutrition and vinegar researcher Carol Johnston.
“Acetic acid is the defining ingredient of all vinegars, and the documented health effects of vinegar are due to acetic acid. But there’s nothing special about the acetic acid in apple cider vinegar,” notes Johnston. “There could be something to ‘the mother’—some redeeming quality to that bacteria,” she adds, “but that’s just speculation. No one’s shown that.”
Most of the claims about the health benefits of vinegar haven’t been tested. Here’s what we know so far.
Lowers blood sugar?
About a dozen studies gave 5 to 27 people a starchy meal with or without one or two tablespoons of vinegar. In roughly half the studies, blood sugar was lower in the hours after the meal with vinegar. In the other half, it wasn’t.1
And in two longer studies that included people with prediabetes, hemoglobin A1c—a long-term measure of blood sugar—was not significantly lower in those who consumed two tablespoons of vinegar a day than in those who got a placebo.2,3
Can a spoonful of vinegar prevent heartburn by restoring stomach acid? That may sound a little backwards, but some health and wellness websites claim that heartburn is due to too little stomach acid, which causes the stomach to churn harder and spew acid back up and into the esophagus.
But Scott Gabbard, a gastroenterologist at the Cleveland Clinic, isn’t sold. “Heartburn is the result of a relaxed sphincter between the stomach and esophagus, and has nothing to do with the amount of acid in the stomach,” he says. “It seems unlikely that vinegar would decrease acid reflux back into the esophagus.”
No studies in people have ever looked.
Helps you lose weight?
Obese adults who consumed two tablespoons of vinegar every day for three months lost just four pounds in a company-funded trial in Japan.4 That’s the only study.
The Bottom Line
The best evidence—though far from solid—is for lowering blood sugar. If you have prediabetes and want to give it a try, make your own salad dressing with at least a tablespoon of vinegar. (Most bottled dressings have too little vinegar.)
If you’d prefer to drink your vinegar, keep in mind that most studies diluted 1 tablespoon in 8 oz. of water. Straight vinegar can burn your mouth and cause ulcers in your esophagus.
And never gargle with vinegar or swish it around in your mouth, as some websites recommend. That can damage your tooth enamel.
1 Nutr. Rev. 72: 651, 2014.
2 J. Func. Foods 5: 2007, 2013.
3 World J. Cardiovasc. Dis. 3: 191, 2013.
4 Biosci. Biotechnol. Biochem. 73: 1837, 2009.