Like garlic to ward off vampires, vinegar remedies are based on traditional and historical practices. Some of which however, do have a practical application.
Believed to have been discovered accidently — a jar of wine left uncovered and transformed into vinegar, it was a popular drink in the days of the Roman Empire. Prior to that, in Assyria, vinegar was used to treat ear-ache, and the Bible mentions its use for treating wounds and sores. Hippocrates treated respiratory diseases with vinegar and pepper around 400 B.C.
 
In the 1860s, Louis Pasteur discovered that the action of bacteria caused wine to be converted to acid and water, and twenty years later, a microbiologist by the name of Hansen identified three kinds of vinegar bacilli.

According to proponents, apple cider vinegar contains a whole host of vitamins, minerals and other nutrients, and it is recommended as a daily tonic. Therapeutically, vinegar has been recommended by proponents for just about everything, including sore throats, ear infections, nose bleed, stings, headaches, hiccoughs, nausea, urinary tract infections, asthma and even to help prevent cancer. The latter it is claimed, due to beta-carotene in apple cider vinegar that strengthens the immune system.

Other than the well established antidote for stings, how do the claims for this wonder liquid hold up under scientific scrutiny? Not very well I’m afraid. Vinegar is a poor source of essential nutrients. It contains no pectin or beta-carotene, only a trace of calcium, iron or protein, and miniscule amounts of amino acids.
 
In America recently, Jack McWilliams, the owner of Third Option Laboratories, Muscle Shoals, Alabama, was served a court order to destroy 13,320 half-gallon bottles of Jogging in a Jug — a mixture of grape juice, apple juice and vinegar — because the product became an unapproved new drug due to health claims made by promoters. Jack McWilliams claimed that his vinegar product had helped him conquer his own arthritis and heart disease, and could reduce the risk of cancer in the internal organs. McWilliams claimed that the reason women craved pickles during pregnancy was because they wanted acetic acid (vinegar).

Despite the court-ordered destruction of these jugs, Third Option Laboratories is still in business and is working with the FDA on ways to market the product legally. Company officials met with FDA in 1992 and agreed to stop making health claims but complaints continued, resulting in action on May 19, 1994 that led to the court-ordered destruction.

Even the authors of books extolling the virtues of vinegar add disclaimers such as, "The publisher is not in any way rendering medical advice and does not intend to replace the advice and care of those in the medical profession". "The publisher makes no claims as to the safety, effectiveness, or precision of any of the remedies or suggestions in this book." Another cautions, "...these are only folk remedies, not scientifically proven cures, no claims are intended as to the safety, or endorsing the effectiveness, of any of the remedies." Caveat emptor!
 

References:

Cardwell, Glenn. 1996. Vinegar can be used for What? the Skeptic, 16(1):32-33. Australian Skeptics Inc.
Food and Drug Administration, Consumer, Jan-Feb, 1996, p.35-6
Jarvis, D. C. 1958, Folk Medicine, Pan Books, London.
Tayler, Joanna. The Wonders of Vinegar, Pan Macmillan, Australia Pty. Ltd.
Thacker, Emily. 1994. The Vinegar Book, Tresco Publishers.


H. Edwards, H. 1999 Alternative, Complementary, Holistic & Spiritual Healing, Australian Skeptics  Inc.