Does vinegar really lower blood sugar?

Why would a shot of vinegar blunt the glucose spike from a carb-heavy meal? Here's what the research shows, and tips for working vinegar into your diet.

Casey Means, MD

Medical Reviewer

Eating a metabolically healthy diet isn’t just about eliminating foods that cause a blood sugar spike, it’s also about incorporating foods that can help aid glucose control. Vinegar is often cited as a food that can have a positive effect on blood sugar, but is it true?

The answer is a solid: probably. Several studies examine the effects of vinegar on glucose processing, and many show positive results. However, much of the research uses very small sample sizes—between 5 and 12 study participants. 

What’s more, the high-carb meals those study participants consume aren’t exactly typical—especially for people trying to eat healthily—often consisting of white bread and juice. How vinegar affects more complex carbs is hard to say. And the studies mostly focus on glucose processing and insulin sensitivity; there’s little evidence it affects weight loss.

Still, the evidence across several studies suggests that this may be more than folklore, so let’s look at the mechanisms involved and how you can take advantage of it in your own diet.

First, What Exactly is Vinegar?

At its most basic, this kitchen staple results from a two-step fermentation process that converts a carbohydrate (usually fruit, rice, potatoes, or whole grains) into alcohol, which is then fermented to vinegar. First, yeast feed on liquid sugar or starch,  fermenting it into alcohol. When the alcohol is exposed to oxygen, naturally-occurring bacteria called Acetobacter create acetic acid—the stuff that gives vinegar its tart, sharp taste, and what’s likely at work when it comes to blunting a post-meal blood-sugar spike.

You’ll find many different types of vinegar at the grocery store, and the differences result from the kind of carbohydrate used to start the fermentation process. The most common varieties include:

  • White distilled vinegar comes from a grain alcohol similar to vodka, which gives it a neutral color and flavor profile.
  • Rice vinegar is made with fermented rice, this type of vinegar tends to have a milder, less acidic taste than the other varieties.
  • Balsamic vinegar is often thicker, darker, and sweeter than the others; it starts with fermented grapes.
  • Apple cider vinegar comes from the liquid of crushed apples and retains a faint apple flavor.
  • Wine vinegar can be either red and white, and the flavor depends on the type of wine used to make it.
  • Malt vinegar comes from fermenting unhopped beer; it displays the same nutty, caramel, sometimes lemony flavor profile as a malted ale.

So How Does Vinegar Impact Blood Sugar?

There isn’t a clear consensus on a precise mechanism behind vinegar’s effect on glucose, but there are a few research-backed theories:

  • The acetic acid in vinegar slows down the rate at which the stomach empties the food you’ve eaten into the small intestine, which in turn slows the breakdown of carbohydrates and gives the body more time to remove glucose from the blood. This ultimately reduces the spike in blood sugar you’d typically see after eating. In one small study of 10 healthy, regular weight volunteers, researchers found that the ingestion of acetic acid as vinegar significantly reduced both blood glucose concentrations and insulin responses after a starchy meal. The study authors wrote: “The mechanism is probably a delayed gastric emptying rate.”
  • Vinegar may act on the body’s cells, increasing their ability to take in glucose, so there’s less of it circulating in the bloodstream. One group of researchers found increased glucose uptake in the forearm muscle cells of people with diabetes who had consumed vinegar compared to those who hadn’t. A study in rats found that balsamic vinegar improves the function of beta cells, which secrete insulin in response to glucose. 
  • Vinegar may also work to balance blood sugar by interfering with disaccharidases—enzymes in the small intestine that break down carbohydrates, says Ashley Koff, RD, a Columbus, Ohio-based dietitian. Anything that acts “to block or subdue the capabilities of the enzymes that break down the carb [curbs the] rapid absorption of the carb as glucose,”  says Koff, blunting the blood sugar rise you might typically see after eating.

Five Ways to Incorporate Vinegar into Your Meals

Have a vinegar-based salad dressing before you eat. This may be especially helpful if you’re planning on having a carbohydrate-rich meal. One study showed that when people consumed 1 ounce of white vinegar with a meal of bread containing 50 grams of carbohydrates, it lowered post-meal glucose spikes and insulin levels. (The researchers soaked the bread in vinegar to distribute its intake, but that may not be the most delicious way to go.)

Another study of healthy people found that eating 100 grams (about a cup and a half) of sliced lettuce dressed with olive oil and vinegar before consuming 50g of white bread carbs experienced significantly lower blood sugar compared to those who ate the same amount of salad dressed with olive oil but no vinegar.

Interestingly, the study authors also compared the vinegar group to a second vinegar group in which they added sodium bicarbonate to the vinegar to neutralize its pH. The scientists found that the neutralized vinegar did not affect blood sugar, suggesting that vinegar’s acidic nature plays a crucial role in its ability to modulate blood sugar.   

Drizzle vinegar over steamed or roasted veggies. It turns out even a small amount of vinegar consumed with meals can help control blood sugar, too. One study found consuming two teaspoons of vinegar with carbs may reduce post-meal blood glucose levels as much as 20 percent. Bonus: the study also found that consuming vinegar with a high-carb meal also increases satiety.

Dilute four teaspoons of apple cider vinegar in water and drink right before you eat. In one study, participants consumed a buttered bagel with orange juice two minutes after drinking either 20 grams of apple cider vinegar or a placebo. When the researchers checked blood glucose levels at 30 and 60 minutes after the meal, they found significantly lower post-meal blood glucose levels in the apple cider vinegar group.

Take six teaspoons of apple cider vinegar before bed. In one small but intriguing study, researchers looked at people with well-controlled Type 2 diabetes and found that drinking two tablespoons of ACV with an ounce of cheese before bed could positively impact blood sugar. Compared to study participants who had water and cheese at bedtime, those who downed the apple cider vinegar reduced their fasting blood sugar levels by up to 6 percent over two days.

Eat more fermented foods. They’re good for your gut and your blood glucose. When researchers in Sweden added fermented milk (a.k.a. yogurt) and pickles (cucumbers preserved in vinegar) to a breakfast of high-carb white bread, they found that the combination reduced blood sugar and insulin levels compared to study participants who just ate the bread. What’s more, the scientists found that adding regular milk and fresh cukes had little impact on blood sugar response.

Related article: 12 glucose-lowering strategies to improve metabolic fitness

Any Downsides to Vinegar Consumption?

According to the American Dental Association, frequent consumption of foods and beverages with high acidity can damage tooth enamel. There’s also a chance you could experience some gastrointestinal woes: According to one study, people who drank vinegar with breakfast reported feeling nauseated. To combat these possible side effects, experts recommend diluting vinegar with water and using it as an ingredient in your meals rather than taking it as a shot.