Apple cider vinegar has been credited with impressive health benefits, including weight loss and better diabetes control. But does it deserve this reputation? What's more, could taking it possibly cause any harm?
In this guide, we'll discuss the pros and cons of apple cider vinegar so you can decide whether or not it is right for you.
What is apple cider vinegar?
Apple cider vinegar is made by adding yeast to crushed apples. This ferments the sugar in the apples into alcohol. The alcohol is then treated with bacteria, which converts it into acetic acid. Because the apples' sugar has been "eaten" by the yeast, apple cider vinegar is virtually carb free.
Acetic acid, the active component of apple cider vinegar, is responsible for its unique taste, smell, and purported health benefits. Acetic acid is also the active component in other types of vinegar, but most studies have used apple cider vinegar, which is why we focus on it in this guide.
Apple cider vinegar has been used as a home remedy for sore throats, indigestion, and general wellness among many cultures and natural health proponents for centuries.
It's also commonly used in salad dressings, for baking, and to pickle and preserve foods.
Potential benefits of apple cider vinegar
Much of the research supporting apple cider vinegar's positive health effects has been conducted in animals, which is considered very weak evidence. However, a few higher-quality studies suggest it might be beneficial for human metabolic health.
Weight loss
Can taking apple cider vinegar help you lose weight? Perhaps.
Apple cider vinegar is often touted as a weight loss aid. Yet most of the scientific evidence for this claim comes from studies showing that acetic acid can increase fat burning and prevent weight gain in mice and rats.
To date, only two clinical trials suggest that apple cider vinegar might help people lose weight.
In the first study, 144 obese adults were assigned to take either 15 ml (1 tablespoon) of vinegar, 30 ml (2 tablespoons) of vinegar, or a vinegar-flavored placebo daily for 12 weeks. They were told to maintain their usual diet and level of activity.
By the end of the trial, participants who took 1 tablespoon of vinegar per day lost an average of 2.6 pounds (1.2 kg) and those in the 2-tablespoon-per-day group lost 3.7 pounds (1.7 kg). They also had small decreases in body fat, waist size, and triglycerides. And the placebo group? They ended up gaining just under a pound (0.4 kg).
In another 12-week randomized trial, 39 overweight adults were assigned to eat a reduced-calorie diet alone or with 30 ml (2 tablespoons) of apple cider vinegar per day. By the end of the study, those in the apple cider vinegar group lost an average of 8.8 pounds (4 kg), compared to 5.3 pounds (2.4 kg) in the diet-only group.
Notably, in both studies participants ate 200-plus grams of carbs per day. Would results have been similar, more impressive, or less impressive if apple cider vinegar was consumed as part of a keto or low-carb diet? It's hard to say, since no study has tested this yet.
And although the results of these studies are encouraging, additional trials are needed to establish that consuming apple cider vinegar promotes weight loss.
Appetite suppression and increased satiety
Some studies have found that vinegar can reduce hunger and help people feel full. Theoretically, this might lead you to eat less without deliberately restricting calories.
In a small trial, people ate identical meals on two separate occasions. When they consumed 20 ml (1.3 tablespoons) of vinegar in water prior to the meal, they ended up taking in 200-275 fewer calories for the day than when they drank water before the meal.
This could be one of the main mechanisms by which apple cider vinegar helps with weight loss.
Better blood sugar control
Strong evidence supports the use of apple cider vinegar for lowering blood sugar levels.
There's an important caveat, though. Vinegar has only been found to reduce post-meal blood sugar increases when it is consumed with a high-carb meal.
Additionally, results from a small study in people with type 2 diabetes suggest that vinegar has stronger anti-glycemic effects when consumed with a meal high in rapidly digested carbs compared to a high-carb meal that is digested more slowly.
If you're following a keto or low-carb diet, at this point there aren't any studies investigating if taking apple cider vinegar will lead to further reductions in blood sugar after meals.
However, results from one study in people with type 2 diabetes suggest that consuming apple cider vinegar with a high-protein, very-low-carb snack before bed may improve fasting blood sugar levels. This was a small study of only 11 people, so additional studies are needed to confirm these findings.
At any rate, if you take insulin or other medication for type 2 diabetes, be aware that your doctor may possibly need to reduce your dosage if you begin taking apple cider vinegar.
Improved insulin sensitivity
In addition to reducing blood sugar levels, apple cider vinegar may help increase insulin sensitivity and decrease post-meal insulin response when consumed with a high-carb meal.
In one study, people with insulin resistance who took 20 ml (1.3 tablespoons) of apple cider vinegar before a high-carb meal had a 34% improvement in insulin sensitivity compared to consuming a placebo drink before an identical meal.
There's also emerging evidence that vinegar might be helpful for women with PCOS (polycystic ovary syndrome) - an insulin-resistant condition that is the leading cause of infertility.
In a very small study, seven women with PCOS took 15 ml (1 tablespoon) of vinegar daily for 3 months. By the end of the trial, six of the women experienced improved insulin sensitivity, and four resumed ovulating.
Other potential benefits
Several anecdotal reports describe people achieving relief from irritable bowel syndrome or reflux symptoms after taking apple cider vinegar. Some people have also reported that using it topically improved their acne and other skin conditions. Although these are interesting accounts, at this point there isn't any published evidence to support them.
Summary
Some high-quality evidence suggests apple cider vinegar may be helpful for weight loss, reducing appetite, lowering blood sugar levels, and improving insulin sensitivity. However, since study participants were eating high-carb diets, it's unknown whether results would be similar in people who eat keto or low carb.
Potential risks of apple cider vinegar
Are there any downsides or health risks to taking apple cider vinegar? There might be, depending on the person. But in general, serious side effects are only seen with very high doses that are significantly over the 15-30 ml amounts used in studies.
Dental erosion
Highly acidic foods and beverages such as fruit juice and soda can cause mineral-rich dental enamel to wear away, increasing the risk of tooth decay. Because vinegar is also highly acidic, there is concern that prolonged or repeated exposure could potentially lead to dental erosion.
In one study, dental enamel from wisdom teeth was soaked in five different types of vinegar for several hours. After four hours, some mineral loss occurred in all of the teeth.
Now, this study was done in a laboratory setting rather than in a human mouth, which produces saliva to help counteract acidity. Also, exposing tooth enamel to apple cider vinegar for several hours wouldn't be possible in real life.
Still, consuming large amounts of undiluted apple cider vinegar on a regular basis can damage teeth. In an extreme case, a 15-year-old girl developed severe dental decay as a result of consuming a daily glass of vinegar in an attempt to lose weight.
Digestive issues
As discussed earlier, vinegar has been shown to reduce appetite and help people feel full. The flip side of this is that it may cause some people to become uncomfortably full, to the point of feeling ill.
In one study, 16 healthy people ate a breakfast sandwich with a beverage containing 25 ml (1.67 tablespoons) of vinegar. After the meal, many of the participants reported lack of appetite along with nausea that lasted several hours.
In some people, feeling overly full after consuming vinegar may be due to delayed stomach emptying. This thought is based on results from a study in people with type 1 diabetes who had gastroparesis, a condition in which nerve damage prevents food from leaving the stomach within a normal time frame.
In this study, when the participants drank 30 ml (2 tablespoons) of apple cider vinegar in water with a meal, food remained in their stomach significantly longer than when they consumed the same meal with plain water.
Other potential issues when consumed in large amounts
Summary
Although consuming up to 30 ml of vinegar per day appears to be safe, some people may develop digestive issues, including nausea and feeling overly full. Also, consuming excessive amounts of vinegar may be harmful to teeth and bones, and could potentially cause other health issues, although this is mainly based on anecdotal reports of extreme examples.
Guidelines for consuming apple cider vinegar safely
When taking apple cider vinegar, the most important things to consider are the amount and the delivery method.
First, let's discuss the amount to take. Studies showing health benefits have used 15 ml (1 tablespoon) to 30 ml (2 tablespoons) of apple cider vinegar per day. In the case of vinegar, more is not better.
It's best to start with 1 tablespoon or even less, divided into two doses consumed at separate meals. If you tolerate this well, you can gradually increase the dose to a maximum of 2 tablespoons per day.
Keep in mind that taking more than 1 tablespoon at a time may cause nausea in some people.
Next, mix the vinegar with water or use it in a salad dressing rather than taking it "straight." This dilutes the vinegar, reducing its acidity and helping to prevent throat burning, dental erosion, or other problems.
You can further limit dental exposure by drinking the vinegar mixture through a straw and rinsing your mouth with plain water afterward.
Summary: Should you take apple cider vinegar?
So, should you take apple cider vinegar?
Studies in people eating high-carb diets suggest it might be helpful for weight loss, blood sugar control, and insulin sensitivity.
At this time, there isn't any evidence that taking apple cider vinegar will lead to improvements beyond those achieved with keto and low-carb eating.
However, for most people, there's no harm in trying it, as long as you do it safely. Start slowly, and gradually work up to a maximum of 2 tablespoons per day, diluted with water.
People with gastroparesis or delayed stomach emptying may be best off avoiding or minimizing vinegar intake to prevent worsening of their condition.
/ Franziska Spritzler, RD, CDE
