Medicinal use of apple cider vinegar can be traced back to Hippocrates, the father of modern medicine, who used it to treat wounds. In the 10th century, Sung Tse, the founder of forensic medicine, recommended use of apple cider vinegar, also known as ACV, together with sulfur to protect from infection when conducting autopsies. In recent times, popularity of ACV has been on the rise. 
Apple cider vinegar is made by fermenting apples for several weeks or months. The sugar in apples is first fermented to alcohol and later to acetic acid, the main active ingredient in apple cider vinegar. During the second phase of fermentation, acetic acid bacteria, also known as acetobacter and some beneficial yeast grow in numbers and accumulate to form a non-toxic layer of slime on the surface of the vinegar. This layer of slime is called mother due to its richness in nutrients and health benefits.
Unfiltered and unpasteurized apple cider vinegar is best regarded for a wide range of benefits from the vinegar and the bioactive bacteria and yeast in it. But what are the health benefits of apple cider vinegar?
Let us explore the folklore, and the truth according to science.
8 Apple Cider Vinegar Health Benefits
1. Helps fight cancer
One of the less known benefits of apple cider vinegar is its potential in fighting cancer. And this is not just folklore. According to a number of studies, consumption of apple cider vinegar could help in the prevention and treatment for cancer.
This study  found that acetic acid, the main ingredient in apple cider vinegar, kills stomach cancer cells. While the study involved the application of acetic acid to stomach cancer cells in test tubes, the study seriously suggests that apple cider vinegar has potential as a treatment for some types of stomach cancers.
Additionally, there are other studies that suggest that consumption of vinegar could offer some level of prevention from esophageal cancer 
It is worth to note that cancerous cells produce lactic acid as they grow. It is also worth noting that the ideal blood pH ranges between 7.35 – 7.45. Deviation from this pH range can negatively impact many functions in the body. For this reason, it is not totally true to assume that high pH will protect from cancer.
2. Regulates blood sugar
Apple cider vinegar helps to stabilize blood sugar levels. It also reduces glycemic index of food. It has been suggested that ACV works similarly to metformin, a drug used by diabetics to control blood sugar level. But because apple cider vinegar is more of a food than a drug, it doesn’t pose the side effects posed by drugs like metformin. 
According to this study , taking two tablespoons of apple cider vinegar at bedtime can reduce fasting glucose levels by 4-6 percent.
This study  found that eating breakfast containing vinegar can decrease blood glucose levels by up to 55 percent.
3. Supports the immune function
Apple cider vinegar has powerful detoxifying properties including liver detoxification and toning the lymphatic system. Additionally, ACV is rich in antioxidants which help reduce free radicals in the body and ultimately reduce oxidative stress. Detoxification and reduction in free radicals help to improve homeostatic balance. [7, 8]
Studies have also shown that ACV is antimicrobial. This means that ACV can be a healthier alternative to chemical medications. And because it is a food product, it can help keep away various microbes and therefore minimize infections. For instance, ACV can kill mycobacterium tuberculosis which is otherwise resistant to most disinfectants. 
ACV can therefore support the immune function by preventing various infections. This is especially helpful in people with compromised immunity.
4. Helps to reduce weight
Regular consumption of apple cider vinegar can help in losing excess weight. ACV is believed to work by regulating appetite and satiety. 
According to a number of studies [11, 12, 13] ACV interferes with the working of some enzymes involved in synthesis of carbohydrates and thereby controls blood glucose levels. ACV also helps the liver to better deal with lipogenesis and synthesis of fatty acids. This leads to healthier cholesterol levels. ACV also helps in detoxification which improves liver functions. All these play a part in supporting weight loss and overall health.
5. Can prevent heart disease
Studies show that apple cider vinegar can help improve cardiovascular health in a number of ways. Regular consumption of ACV helps to lower cholesterol levels in blood. This leads to a lower incidence of high blood pressure and ultimately heart disease. [14, 15, 16]
Most of the available studies have been conducted on laboratory animals. However, there are human studies that have shown that ACV can control blood sugar levels and therefore help manage diabetes. Diabetes complications can lead to high blood pressure and ultimately, heart disease. Another human study conducted on women subjects found that, eating salads containing vinegar led to a significant reduction in the risk of developing heart disease. 
6. Preserves food
Apple cider vinegar has been used successfully to preserve foods for ages. This method of food preservation is making a serious comeback. And while distilled vinegar is used in conventional home pickling, use of apple cider vinegar has been growing steadily especially with health conscious individuals. The only downside is that ACV can discolor fruits and veggies. 
Besides preserving food, the antimicrobial properties of ACV also come in handy when it is used to wash fruits and vegetables. Even the FDA has confirmed that vinegar, besides lemon juice, are readily available, effective household sanitizers. 
7. Treats acne
In addition to its health benefits when taken internally, apple cider vinegar can also help improve skin health. Studies have shown that ACV can help clear acne and acne scars probably due to its antimicrobial properties. 
Additionally, ACV components like acetic acid, citric acid, succinic acid and lactic acid are known to inhibit growth some of the bacteria that cause acne. 
Study have also found that regular application of lactic acid on acne scars for at least three months improves skin tone, color and texture. 
8. Other apple cider vinegar benefits
While there aren’t reliable scientific studies proving it, according to folklore apple cider vinegar has many more health benefits. From various reports, ACV can help treat heartburn, dandruff, warts, relieve sore throat and cough, and soothe sunburn.