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Onions, Flu Protector or Poisonous?

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Our Friend or Our Foe?

This article has been the most popular since the inception of BrightonYourHealth.  Thanks for coming by and take a look around on the site for other foodie posts and nutrition ideas.  If you are interested in the French way of eating, download your E-report on “10 Simple Ways to Eat Like The French Without Having A Food Snob Attitude” by subscribing to BrightonYourHealth here.

The inspiration for “Onions, Flu Protector or Poisonous” was from an email forwarded to me by a friend.  I was so surprised to read that one of my favorite foods could be poisoning my body! 

Did anyone else receive the email recently about onions?  I did, twice, which makes me think that this email has circulated around the net for a while.  The email related three aspects of onions: that they are antibacterial and antiviral, that leftover onions are poisonous and that commercial made mayonnaise will not grow bacteria. Did any of you start to panic a bit after reading the email? Did you believe the email on onions?  It really sounded scientific and true.  But, there was that little doubt in your head.  That is why you did a search on google and found this article.  So, keep reading-will let you know the “skinny” on onions and the real scoop on this story.

When I read the beginning of the email, the story about the family that didn’t get the flu in 1919 because of unpeeled onions around the house; this sounded too unreal.  Firstly, unpeeled onions cannot not “absorb” bacteria or viruses because of the peel around the onion.   Also, the story continues to say that a doctor apparently looked at the flu under a microscope in 1919.  This was impossible at that time because you can only look at viruses under an electron microscopes which wasn’t invented until 1931.  So, this flu story is not true and you can check out to verify this.

The next part of the email is how leftover raw cut up onions are poisonous. Not true again, unless you contaminate the raw onion when you cut them (with dirty hands for example).  Onions emit sulphuric acid which protects them from bacteria after being cut.  They are not poisonous! Leftover onions are fine to use after being cut and stored away in the refrigerator.

Finally, the last part of the mail concerns commercial made mayonnaise.  Commercial made mayonnaise is acidic, which protects it against bacterial growth.  So, if you get sick at that summer picnic on potato salad, usually it was not the commercial mayonnaise that did you in, it was the onion or potato in the salad that caught the bacteria.  You can even leave commercial mayonnaise out of the refrigerator and you won’t get sick!   (Not that I would do this, I feel mayonnaise belongs in the fridge, whether it is commercial or not).  My rule though, for summer picnics, “if it isn’t on ice, and the food has been out for an hour or more, don’t eat it.”  Not following that rule increases your chances to get food poisoning.

So…some of those emails we get that sounds so convincing and actually not true.  So readers, who threw away their leftover onions after reading this erroneous story?  Or did you fill your house with bowls of unpeeled bowls of onions thinking you won’t get the flu?  I guess the lesson is to not believe everything you read, and when in doubt check out: This is a great website to check out rumors.  Being a major fan of onions just couldn’t accept their poisonous properties.  In fact, check out these cool onion goggles.  Do you eat or cook with an onion a day?  These could be a great addition to your kitchen 🙂
RSVP Endurance Tear-Free Onion Goggles, Pink

But before checking those websites out, check out some other interesting articles on this website geared towards a European healthy living theme.  Go to home page or double click on this link to read more on food, recipes and health.  In the meantime, enjoy your onions without any fear and read this article on some true health benefits of onions.

Bon Appetit from BrightonYourHealth.

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56 Responses to Onions, Flu Protector or Poisonous?

  1. Robby @ Aim World April 29, 2016 at 19:29 #

    Ever since in my life I have never heard that onions are poisonous. But with supportive ideas I will believe it in some cases. It is also my goal to let people be aware on how to stop flu affecting someone especially in other member of the family, through our AIM World iProtect product.

  2. Jack April 30, 2013 at 22:03 #

    Onions, garlic,leeks chives,etc, contain sulphur hydroxyl, this poison attacks the brain, the central nervous system,the heart, liver and kidneys, causes anxiety, aggression ,thus it’s harmful physically, emotionally, mentally and spiritualy.

    • e June 11, 2013 at 22:40 #

      Haha, this retard thinks there is “spirituality” in vegetables.

  3. Antonio Marks April 18, 2013 at 07:21 #

    I myself too, don’t believe that onions are poisonous. Anyway, thanks for the effort of sharing this info to us.

  4. Steven April 10, 2013 at 07:40 #

    Please do not use as a source It is unreliable at best, and biased.

  5. Hind Tahboub March 5, 2013 at 21:44 #

    onions dont emit sulfuric acid . in fact , they release enzymes that combine with hydrogen in any wet area and produce the h2s04 formula ( sulfuric acid ) .

    • mbrighton March 5, 2013 at 22:05 #

      Dear Hind, Thank you for this clarification and I appreciate your comment.

  6. MadMan February 14, 2013 at 17:53 #

    Yes, thank you Kerri…we knew that. What they are saying is that it would have been impossible in 1919 to look at a virus because you need an electron microscope? So, I really don’t know what you are trying to say?

  7. MadMan February 14, 2013 at 17:42 #

    No one ever claimed to trust a single source. I can assure there are dozens of other sites that also debunk the onion.

  8. Kerri February 6, 2013 at 00:59 #

    OH and the first Microscope was created in 1595 and the electric one was created in 1931.

  9. Kerri February 5, 2013 at 17:31 #

    I’m sorry but, my whole family had the flu when they came over, so we put cut onions around the house, and within a day and a half we were all better? What happened there?

  10. Eileen February 2, 2013 at 04:57 #

    Also saw this story about onions online….glad to hear it’s not true (my house might have been stinking up the neighborhood) and good about info mayo! My one important comment about onions however, is they are poisonous to cats! Mine is very sick right now and they are having a hard time trying to figure it out. It could possibly be from the table food she occasionally eats that has onions, garlic or chives in it. Be careful what you feed your animals!

  11. Sarah January 28, 2013 at 11:01 #

    Bonjour Mary,

    Ah yes – I’ve been sent this article about onions… having been snivelling, coughing, blowing & sneezing for nearly a month now, I’m getting to the end of my rag! I’ve had enough – it’s ‘snot’ fair! Anyway I cut up onions & put them around my house last night and now I have a smelly house as well as a blocked nose & a cough!!!

    So what do I do with these onions now? I think I’l make a pot of French onion soup…

    Being an ex-restaurateur as well as health & safety orientated, I’m in complete agreement about not leaving food out for more than an hour. Home made mayo is for friends & family because you never know who’s allergic/pregnant/intolerant etc.

    Keep smiling,

    • mbrighton January 28, 2013 at 22:36 #

      Hi Sarah! Thanks for your comment AND your personal report on experiment. Hope your cold gets better soon. Sounds like you need some homemade chicken soup and a long night’s sleep. Bon Courage (Good Luck)

  12. Melissa January 14, 2013 at 19:44 #

    I saw this on Facebook last week and about coughed up my Diet Coke, laughing as I read it! As a microbiologist, I knew right away that this was false – not only because it would have been impossible to look at a virus under a microscope at that time, especially by just taking the onion and putting it under the scope. But even with a regular ocular microscope, you would still need to have the organisms or substance smeared on a slide and stained before ever putting the slide under the scope for viewing.

    And then the fact that they interchanged “bacteria” and “virus” – one of my pet peeves because one is 1000s of times larger than the other and they are NOT the same thing. It’s sad that things like this get forwarded so easily without verificaiton, and then people freak out.

    I do find it interesting that people might still think that mayo causes food poisoning. I’m with you, though – if it’s been out more than an hour, it’s going in the trash. I took some heat at a June wedding reception, because there was raw shrimp cocktail that had been out for hours, long after the ice melted, and I insisted on throwing it away. The looks I got!! 🙂

    • mbrighton January 15, 2013 at 22:54 #

      Thanks for your comment! Coming from a microbiologist, very important!

  13. Suzi January 12, 2013 at 12:18 #

    I am a biologist, the idea that onions absorb bacteria is false, onions along with garlic contain a natural antiseptic called alicillin which is good for you. To eat. Placing them around your house will only make your house smell like onions. They do not magically attract flu viruses or bacteria any more than any other object in your house. If you leave them out eventually they will go green and mouldy just like any other veg. I have personally eaten cut onions several days old and I lived to tell the tale. Don’t believe everything you read on the internet and check your sources carefully.

    • mbrighton January 15, 2013 at 22:57 #

      Hi Suzi! Thanks for your comment, from a professional!

  14. Carisa January 11, 2013 at 07:00 #

    I want to know if anybody ever tested an onion these days and actually found out if its true or not? I’ve seem comment from people who tried and said it made them feel better. Would it be bad if I actually tried putting onions around the house?

  15. Jeff January 9, 2013 at 20:02 #

    Hi Joyce, I studied at Johnson and Wales Uni as a chef I have never been taught this and or heard of this. I don’t know where this silly idea comes from that cut onions become poisonous so quickly. However, like any food where there is moisture and left out at room temperature there will be bacteria growth, its nature. Also refrigerating your food does not stop bacteria growth, it simply slows down the process. You should be much more concerned about fish not being properly stored than onions.

    • mbrighton January 9, 2013 at 22:40 #

      Hi Jeff and Joyce, Thanks so much for your comments. I also have never heard about onions as a food safety issue for cooking. Although I haven’t been in culinary school, I did take classes in cooking and food safety as part of my degree requirements. Are there any other professionals chefs out there that could add their thoughts? Thanks to both commentators, Jeff and Joyce for taking the time to add your comments.

  16. Miaatch January 9, 2013 at 18:28 #

    The fact that you researched this through is really sad! It really takes a hit to any of you credibility! Just saying…

    • mbrighton January 9, 2013 at 22:37 #

      Hi Miaatch, Thanks for your comment and concern that I use as a legitimate research source. No worries, I didn’t research the article through What I said was that I verified my hypothesis that this email was a ‘joke’ and not believable through checking out
      My initial thoughts were that this email had very little credibility. As I read the email through, I noticed the reference to a doctor in 1919 looking at the flu virus under the microscope. It is basic biology that flu viruses can only be seen under an electron microscope-which was invented later than 1919. Plus, as unscientific as it sounds, I have eaten thousands of half cut (and at least) day old onions over the years.I fed half cut onions to my kids….we have never gotten sick from half cut day old onions. Never. Perhaps I wasn’t clear enough in the article. I read the email, knew it wasn’t legitimate, looked up some points online (what year the electron microscope was invented for example) and then just went to to verify that it was a fake email. There is so many email scams circulating, I think is just one avenue to look at to see if the site has anything posted on it. I would never use as a final research conclusion on a health subject. That makes my words unethical if I did this. Hope this clarifies my point on the subject. I appreciate your comment and please keep reading the other articles.

  17. Joyce Varley January 7, 2013 at 02:43 #

    Hi Mary,

    I first heard about cut up onions becoming toxic some years ago….long before this email. My sister in law went to school to become a chef, and she told me they were instructed to never leave cut up onions at room temp for very long, as they would become poisonous.
    Why would they teach this at cooking school, if it were not so? (there are other chefs I have talked to, who were taught the same thing).

    Thanks, Joyce

  18. Judy Shepherd January 3, 2013 at 18:56 #

    Mayonnaise has always been on the shelf in the grocery store; it has never been in the refrigerator department. In fact up until crazies started putting poison into baby food jars, etc., the jars were not even sealed. I remember seeing a lady actually open a mayonnaise jar and smell it, and after replacing the lid, put the jar back onto the shelf. Do you actually think if mayo was sooo dangerous, that it would have ever been sold without store refrigeration and/or being sealed?

  19. Suz January 2, 2013 at 05:53 #

    Take vitamin D!

  20. fonda12 December 31, 2012 at 12:19 #

    I am going to try it any way,I do not want the flu AND i WORK WITH CHILDREN WITH RUNNING NOSES EVERYDAY

  21. Danny December 29, 2012 at 17:16 #

    Exactly Jake! Trusting a single source for verification is often a mistake as I have found with snopes.

  22. arlene December 29, 2012 at 15:54 #

    I have the flu- and I had the flu shot—I was hoping onions might help, having also seen that email going around on facebook. Bummer!

  23. Peter Hamilton December 28, 2012 at 01:48 #

    I can say I haven’t refrigerated mayo for years with no issues. And i think it adds more taste when used at room temp..cold dishes seem to close down my taste buds a little bit…

  24. BB December 1, 2012 at 04:20 # is a site for checking out these legends but to count on it 100% to check for hoaxes is goofy since snopes is a hoax itself.

  25. jake December 17, 2011 at 14:58 #

    My friend, who snopes snopes? Who made snopes an authority on everything in the world? Who can verify snopes? OK, so onions may or may not kill you. Why look to SNOPES as a point of reference?
    Go watch the the spring classic and the tour this year and enjoy France…
    Maybe Lance doped… I’ll check snopes..

    • mbrighton December 17, 2011 at 21:59 #

      Hi Jake, snopes is supposed to be a verification based website so that the information you read on is quite reliable. In truth, the email about the onions seemed to be false even without checking out The basis that onions kill viruses, noted in the famous onion email could not be true. The doctor who supposedly verified the virus thru a microscope in 1919 couldn’t have happened. You cannot see viruses under a normal microscope and the electron microscope, invented later is the only visual way to see viruses. Besides all that, I have been eating tons and tons of half onions for years and I am still alive 🙂 ! Thanks for your comment. Keep them coming!

  26. Mike L. April 15, 2011 at 18:33 #

    Its amazing how one day onions will be good for you and then the next day you’ll find out that they’re not. I love the taste of them personally, I just hate finding all this controversial back and forth evidence lol. I’m sure a dietitian would know the truth, as I have never personally studied this field before.

    • mbrighton April 15, 2011 at 23:38 #

      Hi Mike, Thanks for your input. It goes to show you that dietitians don’t know everything. Even after I read the email about the onions I was almost convinced. I love onions too! The thought of all those half onions I ate that were poisonous! But, my doubts on the validity of this email were too high to just not investigate.Voila! Eat your onions, watch food during warm picnics. Bon Appetit!

  27. julie daigle February 20, 2011 at 19:31 #

    are onions poisonous after cut for a while

    • mbrighton February 23, 2011 at 21:21 #

      No Julie, Onions are not poisonous after being cut and sitting out. Whether I would eat them after sitting out for two weeks….not poisonous, but probably not tasting good…


  1. Heather - January 1, 2013

    @simplyjunebug here honey.

  2. Heather - December 29, 2012

    @TiaRonca Onions, Flu Protector or Poisonous? –

  3. Stephanie Oates - December 29, 2012

    Ok, a friend recently posted a link that puts the onion thing to rest. It's so hard to know which to believe…

  4. mersha christopher - December 22, 2012

    RT @BrightonHealth: Onions, Flu Protector or Poisonous?

  5. Chantal Véchambre - December 18, 2012

    hum… truth or hoax ??? RT @BrightonHealth: Onions, Flu Protector or Poisonous?

  6. Laura Efferson - December 16, 2012

    More on onions

  7. Patty - December 14, 2012

    RT @BrightonHealth: Onions, Flu Protector or Poisonous?

  8. Al Thomson - December 10, 2012

    think this has more credible research

  9. Bootsie - November 30, 2012

    RT @BrightonHealth: Onions, Flu Protector or Poisonous? did some research. This is one of the links I used. @PARTYQTB

  10. Ponch - November 27, 2012

    Onions, Flu Protector or Poisonous? –

  11. Ronald Caranna - November 26, 2012

    Oh the fun of the internet hoaxes abound, why because people love things that defy their very own knowledge and…

  12. Doug Allen - November 20, 2012

    Another facebook rumor – please read.

  13. Steve Hills - November 5, 2012

    If you receive Facebook or email about onions curing plague and being poisonous, ignore it. It's completely untrue.

  14. Myth or Real? Onions: Protecting You from Bacteria « The Majestic Truth - October 29, 2012

    […]… […]

  15. Donna Ellington - September 20, 2012

    Regarding the story circulating saying that using cut onions the next day is poisonous. NOT TRUE….

  16. Americans4Healthcare - September 20, 2012

    Regarding the story circulating saying that using cut onions the next day is poisonous. NOT TRUE….

  17. Donna Ellington - September 20, 2012

    Regarding the story circulating saying that using cut onions the next day is poisonous. NOT TRUE….

  18. Vicki Manuel - September 20, 2012

    the last onion post may have had some misleading information in it so I chose to delete it. Here is a post that…

  19. Karol Lee - November 15, 2011

    @LeahRemini let me save you the trouble of finding out if any of your onion findings are true; Get a flu shot. 🙂

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