Onions are characterized by their rich content of thiosulfinates, sulfides, sulfoxides, and other odoriferous sulphur compounds which are responsible for the onion flavour and produce the eye-irritating compounds that induce tears. What is most important is that the same compounds are very effective against bacteria including salmonella and E. coli. Although the content of sulphur is not as potent as that of garlic, nevertheless the medical benefits are just as effective.
Early American settlers used wild raw onions to treat colds, coughs, and asthma, and to repel insects. In Chinese medicine, onions have been used to treat angina, coughs, bacterial infections, and breathing problems.
The World Health Organization (WHO) supports the use of onions for the treatment of poor appetite and to prevent atherosclerosis (the condition in which an artery wall thickens as the result of a build-up of fatty materials such as cholesterol). In addition, onion extracts are recognized by WHO for providing relief in the treatment of coughs and colds, asthma and bronchitis.
Onions are known to decrease bronchial spasms. An onion extract was found to decrease allergy-induced bronchial constriction in asthma patients.
Onions are known to suppress the growth of potentially harmful bacteria in the colon and they can reduce the risk of tumours developing in the colon. Studies in Greece have shown that a high consumption of onions, garlic and other alliums herbs to be protective against stomach cancer.
There are no known interactions with drugs, although onions can increase the action of anticoagulants.
Apart from the breath smell, large quantities of raw onion can cause a stomach irritation leading to nausea and diarrhoea.
You may not have many friends, but raw onions and garlic should help you outlive most of them.