5 benefits of apple cider vinegar (and a few duds), according to experts

Source: CNN health / Pic: Getty Image / Author: Sandee LaMotte

Apple cider vinegar is one of the most popular natural health products around, with claims that it can do almost anything, including sanitizing toothbrushes, curing diabetes and whittling waistlines.

What are the real benefits of apple cider vinegar, according to science? CNN asked seven experts and looked at dozens of studies to bring you the facts. Here are five ways apple cider (or any vinegar) can help your health -- plus a few popular preconceptions that didn't pass muster.

Lowering blood sugar

What's the most popular use for apple cider vinegar? If a simple internet search is any measure, it involves diabetes.

Registered dietitian Carol Johnston has been studying the effects of acetic acid, the main component of vinegar, on diabetic blood glucose levels, since 2004.

No vinegar, including apple cider, has been shown in studies to significantly alter or prevent diabetes, said Johnston, a professor of nutrition and an associate dean in the College of Health Solutions at Arizona State University.

"If I was to show that vinegar slows progression to diabetes, then I would need hundreds of people and millions of dollars to do the studies, because diabetes has a lot of causes, including genetics," Johnston said.

But studies do show acetic acid can be used as one tool in helping people lower blood sugar. A 2019 randomized clinical trial found "a 10 point decrease in fasting glucose concentrations," Johnston said. "They used two 'spoons' of vinegar in a glass of water twice a day (with the lunch and dinner meals)."

In Johnston's research, the people who benefited most from the use of vinegar were insulin-resistant, a condition called prediabetes.

"In those with prediabetes, it was too good to be true," she said. "It fell a good bit and stayed that way. It may be this is the group that could benefit the most."

It's not just apple cider -- the antiglycemic response can be induced by any sort of vinegar: red and white wine vinegars, pomegranate vinegar or even white distilled vinegar.

But, it only worked in the presence of a starch, she stressed.

"Basically, what acetic acid is doing is blocking the absorption of starch," Johnston said. "If my study subjects eat a starch and add vinegar, blood glucose will go down. But if they drink sugar water and add vinegar, nothing happens. So if you're having bacon and eggs, don't bother. It only helps if you are consuming a starch."

If you choose to use apple cider vinegar, be sure to tell your doctor, said registered dietitian and CNN contributor Lisa Drayer.

"If you're taking a diabetes drug, the vinegar could amplify the effects of your meds," she warned, "and your doctor might want to adjust your dosage."

Weight loss

Weight loss, or dieting, is another popular use for apple cider vinegar, and there is some evidence that it can help.

The most cited study was done with 175 heavy but otherwise healthy Japanese subjects. The 12-week treatment produced lower body weight, body mass index, visceral fat, waist measurements and triglyceride levels. Sounds great, right?

"People didn't really lose that much weight," Drayer said. "Only 2 to 4 pounds in three months over a placebo. That's only a third of a pound a week."

Johnston agreed the study showed "a very, very modest weight loss. In fact, I would say most people who are on a diet for 12 weeks and only lose a couple of pounds aren't going to be very happy."

If you are using apple cider or other vinegars as one part of an overall plan, combining it with a healthy diet, portion control and exercise, it might help, Drayer said. She suggested using balsamic vinegar on salads, in a 4:1 ratio with oil, or adding it to sauces for poultry and fish.

The best way to consume apple cider vinegar is on your salad, experts say.

"If you were doing all the other things to lose weight, it might give you a slight edge. Also, if you're drinking it in water, that's good, as water makes you feel full," Drayer said.

"Sometimes, people get really excited to try something new, and then their other behaviors change, too," she added. "If this helps people be more careful overall, that's a good thing."

But be careful. A paper published last year by Johnston found vinegar can erode tooth enamel. If you do take vinegar for blood sugar, "this stresses the importance of taking the vinegar in a diluted form and with a meal to minimize this effect," Johnston said, adding that "drinking through a straw might even be better!"

Teeth cleaning and whitening

Speaking of teeth ...

"Some people like to use it to remove stains and whiten their teeth," according to one of many online articles touting apple cider vinegar for this purpose:

"I let out an audible gasp when I read about this! It made me cringe, to be honest with you," said Chicago dentist and American Dental Association spokesperson Dr. Alice Boghosian. "You're putting acid on your teeth, the last thing you'd want to do to promote oral health."

A pH of 7 is neutral, and anything less is acid, Boghosian said, adding that many of today's popular apple cider vinegars are in the 2 to 3 pH range -- about the same as stomach acid.

"Anything acidic which contacts your teeth will wear out the enamel, the protective coating, and that will cause cavities," Boghosian added. "This is totally, completely wrong, unless you want to be paying more visits to your dentist."

A healthier option would be to brush your teeth twice a day for two minutes with a whitening toothpaste with the American Dental Association seal, she said. "That shows it's been tested to do what it's supposed to do."

Other articles promote rinsing your mouth with apple cider vinegar, soaking dentures with a diluted mixture or using it to clean a toothbrush.

"You just have to rinse off your toothbrush, get all the toothpaste out, and let it air out. That's all you have to do," Boghosian said. "Cleaning dentures or rinsing with vinegar is not a good idea. It too could put your teeth at risk. And just think how it might affect the metal on partial dentures."

Mosquito bites

The internet also touts apple cider vinegar as a treatment for skin infections and acne, a way to fight lice and dandruff, as a natural wart remover or an anti-aging treatment.

"It will dry out a pimple, but it's not an anti-aging method," said dermatologist Dr. Marie Jhin, a spokesperson for the American Academy of Dermatology. "I wouldn't recommend it. We have much more effective and safe methods today than this."

While it can help with sunburn, there are many other good remedies so "we don't usually suggest that to patients," Jhin said.

One use she can agree with: "I do love it for bites, especially mosquito bites. It's a very underutilized home remedy. If you have a lot of bites, put two cups in a full tub of water and soak. It will help with itching," she said.

But don't turn to it to get rid of head lice or warts. One study found vinegar to be the least effective natural method to eliminate lice, and as for warts, they "are caused by a virus, so there's no cure," Jhin explained.

"You can dab a diluted version of apple cider vinegar on a wart with a Q-tip, and it's going to help remove dead skin, which is what we do in the office by paring it down, cutting it out or burning it with liquid nitrogen. But it's not going to be as fast or effective as what we do in the office," she said.

American Academy of Dermatology spokesperson Dr. Michael Lin, director of the Advanced Dermatology and Skin Cancer Institute in Beverly Hills, has a more negative perspective on home use.

"I've had quite a few patients harmed by apple cider vinegar," Lin explained. "One terrible example was a man trying to treat genital warts. When he came into the office, the entire area was raw, burned by the vinegar.

"I don't know if he was using it full-strength, but whatever he was doing it was too strong," he continued. "He probably has permanent scarring from that natural home treatment."

Lin said he feels more comfortable recommending distilled white vinegar, as it is created to a standardized formulation of 5% acidity.

"With apple cider vinegar, you don't know what strength you're getting," Lin said. "It depends on the brand, and even among batches within a brand, you could get different concentrations of acidity."

"If you do choose to use apple cider vinegar, try to buy a name brand that clearly labels the acidity level. And whatever you do, don't use it full-strength."

He suggested a 1:10 ratio.

All-purpose cleaner

Because of apple cider vinegar's antimicrobial properties, it is often suggested as a natural cleanser for the home.

The acid is effective against mold, but according to the Pesticide Research Institute, an environmental consulting firm, so are salt, lemon juice, hydrogen peroxide, tea tree oil and baking soda.

Many of those also smell better.

Apple cider vinegar is biodegradable, and because of its low pH, it's great against alkaline grime such as hard water and mineral deposits, as well as soap scum.

But it won't cut grease. Why not? Just think of a simple oil and vinegar salad dressing. After mixing, the oil and vinegar quickly separate because oil is nonpolar, while vinegar and water are polar, meaning they are not attracted to each other.

Will apple cider or other vinegars sanitize or disinfect your home? Probably not enough to make you feel germ-free.

This 1997 study showed that undiluted vinegar had some effect on E. coli and salmonella, but a study conducted in 2000 showed no real impact against E. coli or S. aureus, the common staphylococcus bacteria responsible for most skin and soft tissue infections.

That 2000 study also showed vinegars to be quite effective against the waterborne bacteria Pseudomonas aeruginosa, mostly found in hospitals and untreated hot tubs. It was also effective against Salmonella enterica, a rare pig-borne version of salmonella.

If you do choose to use a vinegar to clean your home, never mix it with bleach or ammonia, because it will create toxic chlorine or chloramine gases.

Food preservative

Used for centuries to preserve food items such as pickles and pig's feet, vinegar is now becoming popular as a natural preservative in processed meat and poultry items as well.

Most home pickling uses 5% distilled white vinegar because it doesn't affect the color of the vegetables or fruits, but apple cider vinegar is a popular choice due to its mellow, fruity flavor. Do know, however, that it will turn most fruits and veggies dark.

Apple cider and other vinegars are used by some as a food wash to reduce the number of bacteria or virus on fruits or vegetables.

Another popular use for apple cider, and other vinegars, is as a food wash to reduce bacteria or viruses on the surface of fruits and vegetables. Studies have had varying results, often depending on the type of fruit or vegetable and the amount of time spent in the vinegar solution.

Canada's National Collaborating Centre for Environmental Health says vinegars "may damage the organoleptic properties of produce," or how they taste and smell, and has "limited antimicrobial efficacy."

Cough and sore throat

The use of vinegar medicinally starts with the father of modern medicine, Hippocrates. He would mix it with honey and use it for chronic coughs and sore throats, and the suggestion continues today across the internet.

Many parents might think this is a natural and safe option for their children. The American Academy of Pediatrics doesn't have an official stance on the use of apple cider or other vinegars as a health aid, but spokeswoman Dr. Jennifer Shu urges caution.

"I would just think that the vinegar would irritate the throat even more," said Shu, an Atlanta pediatrician and author of "Food Fights." "But diluting it and mixing it with other ingredients such as salt or honey might decrease any pain that the vinegar might cause."

Arizona State's Johnston cautions against trying any vinegar straight, due to the risk of inhaling the liquid and damaging the lungs.

"Vinegar has that strong smell and puckering taste, so if you take a breath, you could inhale it into your lungs as you swallow," she said. "It can burn the lungs a little, because it is an acid."

"It can also burn your esophagus," said Dr. Andrew Freeman, director of cardiovascular prevention at National Jewish Health in Denver. "And if you're predisposed to reflux, ulcers or stomach problems, it could certainly make those worse."

Heart disease and cancer

If you're a rat worried about heart disease, put apple cider and other vinegars on your shopping list.

Studies show the vinegar can reduce blood pressure, triglycerides and total cholesterol in rodents fed a high-fat, cholesterol-rich diet. But full-blown studies have not been conducted in humans.

Freeman, who serves on the American College of Cardiology's prevention board, said there could be some benefit due to its antioxidant properties, like other heart-healthy fruits and vegetables, such as broccoli and blueberries.

"There are some indicators that using vinegar can improve arterial health and improve blood cholesterol, and there's even more power if combined with green leafy vegetables," Freeman said.

"The data is not particularly strong or overwhelming, but vascular health may be enhanced," Freeman said. "What's best to avoid heart disease is to exercise and eat a low-fat, plant-based diet."

Freeman further recommends using apple cider or other vinegars on salads, to maximize the benefits and reduce any reactions to the acidity.

What about cancer? Japanese scientists have inhibited the growth of human leukemia and other cancer cells in petri dishes by exposing them to sugar cane vinegar and Japanese rice vinegar. Other studies showed a reduction in tumors and a prolonged life by adding rice vinegars to drinking water and food in rats and mice, respectively.

Studies in humans are nonexistent.

So, does apple cider vinegar measure up to its positive internet reputation? If you consider that almost any other vinegar will produce the same benefits, not so much.

There are also some serious downsides, if used full strength and inappropriately. As the experts suggest, make sure you check with your doctor before giving it a try.

"When you do a search for apple cider vinegar you see so many claims, and people will try it, searching for that natural cure-all," Drayer said.

"Whether any of those claims are based on science is another matter."