The notion that onions are "bacteria magnets" has been circulating for centuries, but with the advent of the Internet this theory has gone viral. 

There's a reason why most savory recipes call for onions; their strong flavor adds dimension to even the simplest dish, and they contain several health benefits to boot. According to Nutrition Data, onions are rich in dietary fiber, vitamin B-6, potassium, manganese and vitamin C. WebMD lists onion supplements as potential aids for digestion, heart health, blood circulation and diuresis. Not bad for something that has caused more than its fair share of tears in the kitchen.
But are the health benefits of onions only reaped when this vegetable is consumed? Widespread folklore says no. The National Onion Association traces the myth that onions are capable of preventing disease to the 1500s, beginning with the thought "that placing a cut raw onion in rooms throughout a residence could protect its occupants from getting the bubonic plague." The onion was supposed to serve as a magnet for miasma, the culprit once thought to be responsible for sickness. According to the Science Museum in London, the miasma theory placed the blame for disease on "the presence in the air of a miasma, a poisonous vapour in which were suspended particles of decaying matter that was characterised by its foul smell." Contagion: Historical Views of Diseases and Epidemics, a publication from Harvard University's Open Collections Program, notes that when germ theory emerged in the 1800s, it replaced miasma as the accepted explanation for disease transmission. As we have gained a better understanding of how bacteria and viruses work, miasma theory has been rendered obsolete among medical professionals and scientists.

However, remnants of miasma theory's legacy persist to this day. Despite the debunking of that theory, onions were still being used as traps to deliberately attract illnesses well after medieval times. Snopes investigated the claims of onions being "bacteria magnets" and uncovered writings from the 19th and 20th centuries -- and even as recent as a chain email from 2009 that went viral as the swine flu was making headlines -- that chronicled the vegetable being used in this way. The thought that onions absorb toxins was so pervasive, cookbook author Sarah McCann, under the pen name Zola Gorgon, wrote a blog post in March of 2008 (which has since been taken down but was reproduced here) claiming onions are responsible for food poisoning because their absorbent properties draw in contaminants. Her post caused such a stir that the National Onion Association issued an official statement refuting McCann's post.

To further dismiss the supposed magnetic qualities of onions, several professionals have given their opinions on the matter. In 2012, Joe Schwarcz, director of McGill University’s Office for Science and Society, responded to the chain email with this statement:

"The fact is that onions are not especially prone to bacterial contamination. In fact, quite the opposite. Onions feature a variety of sulphur compounds that have antibacterial activity. ... Furthermore, cutting an onion triggers the release of enzymes that initiate a chemical reaction producing propenesulfenic acid, which in turn decomposes to yield sulphuric acid ... sulphuric acid also inhibits the growth of bacteria. Also, a cut onion’s surface dries out quickly, reducing the moisture that is needed for bacteria to multiply. And of course, to have bacteria multiply, you need some source of bacteria in the first place. Where would these come from?  Bacteria are not spontaneously generated. They have to be somehow present to start with. Cutting boards and dirty hands are a possible source, but food spoilage bacteria do not become airborne, you need contact."

He concludes, "there is no reason to suggest that onions are in any way more risky than other foods and avoiding onions is not only unnecessary but unhealthy" because of onions' health benefits when consumed.

In an interview with Best Food Facts in 2013, Dr. Ruth MacDonald, chair and professor of the Department of Food Science & Human Nutrition at Iowa State University, concurs with Schwarcz's response, stating:

"No, onions do not absorb bacteria. The idea that a vegetable would attract and suck into itself bacteria from the air is not even logical. The onion may turn black because it would eventually rot from both cell breakdown events and bacterial contamination if you left it out, not because it absorbs germs. ... Eating these vegetables provides antioxidants that can have health benefits, but they are unlikely to prevent or cure disease."

Nevertheless, there are still individuals who believe in the toxin-attracting powers raw onions hold. In a video uploaded to YouTube on April 7, 2015, self-described "health, fitness, mindfulness and green living advocate" David Benjamin claims on his blog Healthy Wild And Free that placing onions in your socks overnight serves as a panacea "to purify your blood, and kill germs and bacteria." His reasoning combines the aforementioned onion myths with reflexology, which he explains thus: "the bottom of the feet have many different nerve endings, approximately 7,000 (basically meridians) that directly link to different organs within the body." The graphic below shows which organs are supposedly linked to which part of the foot:

Benjamin asserts that by evenly distributing slices of raw onion along the bottom of the foot "like a platform ... the natural healing powers of the onion will go to work through your skin (trans-dermal application) purifying your blood and killing bacteria and germs as well as absorbing toxins" while you sleep. The socks simply keep the onions in place.

Benjamin is not alone in suggesting this remedy. Jennifer Thompson of Healthy Bliss published a blog post in 2013 listing numerous anecdotes that laud raw onions as a versatile healing tool. Her followers on social media were especially enthusiastic about the sock technique.

Onions' health benefits are apparent from a nutritional standpoint, but science suggests their status as "bacteria magnets" is unfounded. Of course, there are still individuals out there who fervently believe in the power of onion socks. What's your stance on this craze? Would you consider putting onions in your socks while you sleep? Share your thoughts with us in the comments section.