The onion, at one time or another, has been enthusiastically recommended as a remedy for colds in the head and worms in the intestines. For centuries, the onion's medicinal value has been praised by witch doctors, old wives and bartenders. Rome's Pliny the Elder listed the onion as a cure for 28 diseases. Early New England settlers believed that the onion would prevent fits; Neapolitans of the Middle Ages thought it averted the evil eye. A 16th Century French surgeon, Ambroise Parè, used it instead of ointment to heal powder burns.
The onion may be coming back into medical fashion. The Russians have discovered that onion and garlic vapors heal wounds (TIME, March 13, 1944). They called the germ-killing substance a phytoncide (meaning: a killer derived from plants). Now Food Chemist Edward F. Kohman has found that the active chemical agent in onions is a thioaldehyde, a close relative of the common antiseptic, formaldehyde. Chemist Kohman put raw onions through an ordinary household meat grinder, distilled the onion vapors, put them through a series of chemical tests. In a recent issue of Science, he reported finding about 1/20 of a gram of thioaldehyde in a pound of raw onions.
The germ-killing thioaldehyde, Kohman said last week, probably does not exist as such in the onion. More likely, it is produced by the complicated enzyme activity that goes on in the onion when it is cut. Cooking would eliminate it completely; a boiled onion is no more good for a cold than a boiled turnip. But chewing a raw onion might help a cold (it would undoubtedly prevent spread of colds by keeping non-onion eaters away from the cold sufferer).