Apple cider vinegar

Over the centuries, vinegar has been used for countless purposes: making pickles, killing weeds, cleaning coffee makers, polishing armour, and dressing salads. It's also an ancient folk remedy, touted to relieve just about any ailment you can think of. In recent years, there have been claims that apple cider vinegar is an effective health tonic, which is why it's often sold in both the condiment and the health supplement aisles of the supermarket. While many of the folk medicine uses of vinegar are unproven (or have been disproved), a few have been the subject of medical research. Some small studies focused on several conditions, from diabetes to obesity.

So does consuming apple cider vinegar make sense for your health? Or is vinegar best used for cleaning stains and dyeing Easter eggs? Here's a rundown of the facts.

What is apple cider vinegar?

Vinegar is a product of fermentation. This is a process in which sugars in a food are broken down by bacteria and yeast. In the first stage of fermentation, the sugars are turned into alcohol. Then, if the alcohol ferments further, you get vinegar. The word comes from the French, meaning "sour wine." While vinegar can be made from all sorts of things - such as many fruits, vegetables, and grains -- apple cider vinegar comes from pulverised apples.

The main ingredient of apple cider vinegar, or any vinegar, is acetic acid.  However, vinegars also have other acids, vitamins, mineral salts and amino acids.

Apple cider vinegar: Cure for anything?

During the alternative medicine boom of recent years, apple cider vinegar pills have become a popular dietary supplement.

Look on the back of a box of supplements -- or on the Internet or in the pages of any one of the many books on vinegar and health -- and you'll find some amazing and often unsubstantiated claims. Apple cider vinegar is purported to treat numerous diseases, health conditions and irritations.  To name a few, it's supposed to kill head lice, reverse some of the signs of ageing, ease digestion and wash "toxins" from the body.

Most of these claims have no evidence to back them up. Some - like vinegar's supposed ability to treat lice or warts - have actually been studied, and researchers found nothing to support their use. Other claims have been backed up by studies, but with a catch: vinegar may work, but not as well as other treatments. For instance, while vinegar is a disinfectant, it doesn't kill as many germs as common cleaners. And while vinegar does seem to help with jelly fish stings - an old folk remedy - hot water works better.

Scientific evidence of apple cider vinegar benefits

There are some medical uses of vinegar that may show promise, at least according to a few studies.  Here's a list of some more recent ones.

Diabetes. The effect of vinegar on blood glucose levels is perhaps the best-researched and the most promising of apple cider vinegar's possible health benefits. Several small studies have suggested that vinegar may help maintain lower glucose levels. For instance, one in 2007 was conducted at Arizona State University and reported in the US journal Diabetes Care. The study of 11 people with type 2 diabetes found that taking two tablespoons of apple cider vinegar before bedtime lowered glucose levels in the morning by 4%-6%.