Apple cider vinegar is a natural tonic.
It has several health benefits that scientific studies in humans support.
However, people have also raised concerns about its safety and possible side effects.
This article takes a look at apple cider vinegar’s potential side effects.
It also provides instructions on how to consume apple cider vinegar safely.
What is apple cider vinegar?
Apple cider vinegar is made by combining apples with yeast.
The yeast converts the sugar in the apples into alcohol. Bacteria are then added to the mixture, which ferments the alcohol into acetic acid.
Acetic acid makes up about 5–6% of apple cider vinegar. It is classified as a “weak acid,” but it still has fairly strong acidic properties when it is concentrated.
In addition to acetic acid, vinegar contains water and trace amounts of other acids, vitamins, and minerals.
Several studies in animals and humans have found that acetic acid and apple cider vinegar may promote fat burning and weight loss, decrease blood sugar levels, increase insulin sensitivity, and improve cholesterol levels.
Unfortunately, apple cider vinegar has been reported to cause some side effects.
This is particularly true in large doses.
Although small amounts are generally fine and healthy, consuming too much can be harmful and even dangerous.
1. Delayed stomach emptying
Apple cider vinegar helps prevent blood sugar spikes by reducing the rate at which food leaves the stomach and enters the lower digestive tract. This slows down its absorption into the bloodstream.
However, this effect may worsen symptoms of gastroparesis, a common condition that affects people living with diabetes.
In gastroparesis, the nerves in the stomach don’t work properly, so food stays in the stomach too long and is not emptied at a normal rate.
Symptoms of gastroparesis include heartburn, bloating, and nausea. For type 1 diabetics who have gastroparesis, timing insulin with meals is very challenging because it’s hard to predict how long it will take food to be digested and absorbed.
One controlled study looked at 10 patients with type 1 diabetes and gastroparesis.
Drinking water with 2 tablespoons (30 mL) of apple cider vinegar significantly increased the amount of time that food stayed in the stomach, compared to drinking plain water.
Newer research is needed to better understand the effect apple cider vinegar has on blood sugar.
2. Digestive side effects
Apple cider vinegar may cause unpleasant digestive symptoms in some people.
Human and animal studies have found that apple cider vinegar and acetic acid may decrease appetite and promote feelings of fullness, leading to a natural reduction in calorie intake.
However, one controlled study suggests that in some cases, appetite and food intake may decrease due to indigestion.
The people who consumed a drink containing 25 grams (0.88 ounces) of apple cider vinegar reported less appetite but also significantly greater feelings of nausea, especially when the vinegar was part of an unpleasant-tasting drink.
3. Low potassium levels and bone loss
There are no controlled studies on apple cider vinegar’s effects on blood potassium levels and bone health at this time.
However, there is one case report of low blood potassium and bone loss that was attributed to large doses of apple cider vinegar taken over a long period of time.
A 28-year-old woman consumed 8 ounces (250 mL) of apple cider vinegar diluted in water on a daily basis for 6 years.
She was admitted to the hospital with low potassium levels and other abnormalities in blood chemistry (15).
What’s more, the woman was diagnosed with osteoporosis, a condition of brittle bones that is rarely seen in young people.
Doctors who treated the woman believe the large daily doses of apple cider vinegar led to minerals being leached from her bones to buffer the acidity of her blood.
They also noted that high acid levels can reduce the formation of new bone.
Of course, the amount of apple cider vinegar, in this case, was much more than most people would consume in a single day — plus, she did this every day for many years.
4. Erosion of tooth enamel
Acidic foods and beverages have been shown to damage tooth enamel.
Soft drinks and fruit juices have been more widely studied, but some research shows the acetic acid in vinegar may also damage tooth enamel.
In one lab study, enamel from wisdom teeth was immersed in different kinds of vinegar with pH levels ranging from 2.7–3.95. The kinds of vinegar led to a 1–20% loss of minerals from the teeth after 4 hours.
Importantly, this study was done in a lab and not in the mouth, where saliva helps buffer acidity. Nevertheless, there’s some evidence that large amounts of vinegar may cause dental erosion.
A case study also concluded that a 15-year-old girl’s severe dental decay was caused by consuming 1 cup (237 mL) of undiluted apple cider vinegar per day as a weight loss aid
5. Throat burns
Apple cider vinegar has the potential to cause esophageal (throat) burns.
A review of harmful liquids accidentally swallowed by children found acetic acid from vinegar was the most common acid that caused throat burns.
Researchers recommended vinegar be considered a “potent caustic substance” and kept in childproof containers.
There are no published cases of throat burns from apple cider vinegar itself.
However, one case report found that an apple cider vinegar tablet caused burns after becoming lodged in a woman’s throat. The woman said she experienced pain and difficulty swallowing for 6 months after the incident.
6. Skin burns
Due to its strong acidic nature, apple cider vinegar may also cause burns when applied to the skin.
In one case, a 14-year-old girl developed erosions on her nose after applying several drops of apple cider vinegar to remove two moles, based on a protocol she’d seen on the internet.
In another, a 6-year-old boy with multiple health problems developed leg burns after his mother treated his leg infection with apple cider vinegar.
There are also several anecdotal reports online of burns caused by applying apple cider vinegar to the skin.
7. Drug interactions
A few medications may interact with apple cider vinegar:
- Diabetes medication. People who take insulin or insulin-stimulating medications and vinegar may experience dangerously low blood sugar or potassium levels.
- Digoxin (Lanoxin). This medication lowers your blood potassium levels. Taking it in combination with apple cider vinegar could lower potassium too much.
- Certain diuretic drugs. Some diuretic medications cause the body to excrete potassium. To prevent potassium levels from dropping too low, these drugs shouldn’t be consumed with large amounts of vinegar.