Mythbusting: Myths of Onions and Vampires (or, the Flu)

While clicking around on Facebook today, I spotted a post on a friend’s wall that claimed that leaving an onion out will absorb germs (e.g. the flu virus) like a magnet, and prevent you from getting sick.  This is a very coarse summary based on the text which you can read in full here for a few chuckles (it’s a long one):

My response, in brief:

Dear Adonain Danny Rivera,
I don’t know who you are, but you’re an idiot.


Here’s the thing.  Viruses, bacteria, and diseases don’t work this way.  You can’t “attract” them in one direction and lure them away from another.  While it’s nice to wish that this works, it doesn’t.  They breed and increase in concentration opportunistically, which means according to the law of entropy, they will move from a space of higher concentration to a lower concentration.  Providing a more hospitable place for them to flourish doesn’t attract them away from another place like a herd of deer to a food source, it just creates an oasis where more can be produced and subsequently spread to other places.  We’ll be writing an article on some of the issues of sanitization and food safety soon.


Understandably, people are concerned because of the “flu epidemic” which has been spreading around especially in New York, to the point that Governor Cuomo has declared a statewide public health state of emergency (link: , the worst since 2009.  Because of this, we’re willing to try some less-than-conventional remedies, or homeopathic solutions to try and stay safe.


So back to that post – let’s ask, what might be going on here? The one caveat I will offer is I don’t know if this actually works, but this is merely a hypothesis of what might be happening if it does.


A brief aside about homeopathic remedies: I believe that over the years through trial and error, natural remedies have discovered valid treatments and proven themselves somewhat effective but they are no joke, and are certainly not harmless just because they’re “natural” (otherwise they wouldn’t be effective) – but we know more today so let’s understand a little bit about maybe what’s going on so we don’t unintentionally make the situation worse.

Your onion is not a germ magnet.  At least, no more so than other foods, and as discussed, luring bacteria or in this case viruses to a more hospitable environment doesn’t mean they’re going there instead of to you.  In fact, when was the last time you cut an onion?  It was pretty unappealing to stick around, no?


Cutting an onion (really, breaking the cells) releases Alliinase:

This lovely thing is an enzyme that creates sulfenic acid (the stuff that makes your eyes tear) by reacting with amino acid sulfoxides:

Sulfenic acid, which is a type of allicin compound (that can also be derived from cousins of the onion such as garlic), has clinically demonstrated anti-bacterial and anti-viral properties.


Its anti-bacterial properties include effectiveness in inhibiting the Staphylococcus aureus (aka Staph) bacteria which is responsible for all sorts of nasty stuff including skin infections, respiratory diseases (e.g. sinus infections), and food poisoning.  I won’t go into the whole epidemiology of it, but maybe I can get my sister to write a guest article on it.


As for its anti-viral properties, a small study (Ref section, Allicin: was done which demonstrated that purified Allicin (which incidentally is inactivated by cooking) was highly effective in preventing (not treating) the common cold by 64%, and reduced the duration by 70% – again the trial only focused on it as a preventative measure.


Now, given all that information, let’s turn back to the claims of the post – It could be that as you’re inhaling the alliinase, it is creating small concentrations of sulfenic acid in your respiratory system, which is in turn killing or at least inhibiting the flu virus.


If this is indeed really what’s happening, then you should get the strongest, ripest, most pungent (probably Spanish) onions, mash and mince them as much as possible to break as many cells as you can releasing all that Alliinase goodness, and leave it in the open while preparing for a good cry.  The roots of the onion contain the highest concentration of Alliinase, so you’d want to grind up that part especially well.  Water incidentally dilutes the concentration of Alliinase (which is why soaking onions in water will prevent tears) so you want to keep it away from moisture.  Likewise, moisture, dampness, and humidity create breeding grounds for viruses and bacteria (water being essential to life even at the microscopic level).  This is why hotels maintain an exceptionally low humidity level in their facilities, and why I’ve adopted the practice of not using my humidifier during certain weeks during the winter months when risk of colds are particularly high.


To tie up the other little loose and completely unrelated threads of the post which were probably added as factoid tidbits to lend credibility:

  • Yes, there is some truth to the blackening and spotting of onions.  It looks like it’s attracting germs, but that is actually just mold and yes, that is a food safety issue. We actually see that all the time at the soup kitchen because we have onions that sit out for a while (especially during the week) before we get to use them.  Trim off those parts if you can, otherwise toss.
  • If onions really were germ magnets and unsafe to eat, everyone we served at the soup kitchen would be deathly ill, but we’ve had no issues to date.  Onions are actually pretty hearty and can sit out in the open for up to two weeks in some cases without needing refrigeration (they’ll just get more ripe and potent – read: juicer, and make you cry more). The usual sauté and they will be fine – they will still be safe to eat (I have no idea about for dogs though).
  • The whole issue with homemade mayo is that traditional recipes are an emulsification of raw egg yolks, oil and a little (not much) acid with starch (food for microorganisms).
  • Commercial mayo is made with pasteurized eggs, and has significantly more acid with a pH between 4.0-4.5, the equivalent pH of beers, berries, and some milder citrus fruits which obviously can be left out without issues for food safety other than their normal spoilage.
  • Mike reminded me that onions have been linked to some cases of botulism in the past, but these cases are extremely rare. In general, there are an average of 110 botulism cases a year, most of which are infants ( The most recent onion related cases were 28 individuals eating at the same restaurant in Illinois in 1983 ( You are more likely to encounter botulism from an expired home-canned vegetables, then from onions.

Stay Healthy and Happy Crying!

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