Are Onions Poisonous?

Onions (Photo Credit: Healthcarenewsblog)
Onions (Photo Credit: Healthcarenewsblog)

There is an email circulating since 2008 claiming that cut onions are “magnets for bacteria” and should never be stored for later use (even in the fridge for a few days) as they will cause food poisoning.  Perhaps you’ve received same forwarded email, too?

I think I have gotten such forwarded message more than ten times, and it really got me curious; so I browsed and read about onions for some hours.

A Must Read :   DANGER of cut and opened ONIONS   (Is this true??? )       

Onions (Photo Credit:  Healthcarenewsblog)
Onions (Photo Credit: Healthcarenewsblog)

To quote:

“Onions are a huge magnet for bacteria, especially uncooked onions. You should never plan to keep a portion of a sliced onion.

It is dangerous to cut an onion and try to use it to cook the next day, it becomes highly poisonous for even a single night and creates toxic bacteria which may cause adverse stomach infections because of excess bile secretions and even food poisoning.


In 1919 when the flu killed 40 million people. There was this Doctor that visited the many farmers to see if he could help them combat the flu… Many of the farmers and their families had contracted it and many died.

The doctor came upon this one farmer and to his surprise, everyone was very healthy. When the doctor asked what the farmer was doing that was different the wife replied that she had placed an unpeeled onion in a dish in the rooms of the home, (probably only two rooms back then). The doctor couldn’t believe it and asked if he could have one of the onions and place it under the microscope.  She gave him one and when he did this, he did find the flu virus in the onion. It obviously absorbed the bacteria, therefore, keeping the family healthy.


Now, I heard this story from my hairdresser. She said that several years ago, many of her employees were coming down with the flu, and so were many of her customers. The next year, she placed several bowls with onions around in her shop. To her surprise, none of her staff got sick. It must work. Try it and see what happens. We did it last year and we never got the flu.


Now there is a P. S. to this.  for I sent it to a friend in Oregon who regularly contributes material to me on health issues. She replied with this most interesting experience about onions:

Thanks for the reminder. I don’t know about the farmer’s story…but, I do know that I contacted pneumonia, and, needless to say, I was very ill… I came across an article that said to cut both ends off an onion put it into an empty jar, and place the jar next to the sick patient at night. It said the onion would be black in the morning from the germs…sure enough it happened just like that…the onion was a mess and I began to feel better.


Another thing I read in the article was that onions and garlic placed around the room saved many from the black plague years ago. They have powerful antibacterial, antiseptic properties.

This is the other note.

Lots of times when we have stomach problems, we don’t know what to blame. Maybe it’s the onions that are to blame. Onions absorb bacteria is the reason they are so good at preventing us from getting colds and flu and is the very reason we shouldn’t eat an onion that has been sitting for a time after it has been cut open.



I had the wonderful privilege of touring Mullins Food Products, Makers of mayonnaise. Questions about food poisoning came up, and I wanted to share

What I learned from a chemist.

Ed, who was our tour guide, is a food chemistry whiz. During the tour, someone asked if we really needed to worry about mayonnaise. People are always worried that mayonnaise will spoil. Ed’s answer will surprise you. Ed said that all commercially-made mayo is completely safe.

“It doesn’t even have to be refrigerated. No harm in refrigerating it, but it’s not really necessary.” He explained that the pH in mayonnaise is set at a point that bacteria could not survive in that environment. He then talked about the summer picnic, with the bowl of potato salad sitting on the table, and how everyone blames the mayonnaise when someone gets sick.

Ed says that, when food poisoning is reported, the first thing the officials look for is when the ‘victim’ last ate ONIONS and where those onions came from (in the potato salad?). Ed says it’s not the mayonnaise (as long as it’s not homemade mayo) that spoils in the outdoors. It’s probably the ONIONS, and if not the onions, it’s the

He explained onions are a huge magnet for bacteria, especially uncooked onions. You should never plan to keep a portion of a sliced onion.. He says it’s not even safe if you put it in a zip-lock bag and put it in your refrigerator.

It’s already contaminated enough just by being cut open and out for a bit, that it can be a danger to you (and doubly watch out for those onions you put in your hotdogs at the baseball park!). Ed says if you take the leftover onion and cook it like crazy you’ll probably be okay, but if you slice that leftover onion and put on your sandwich, you’re asking for trouble. Both the onions and the moist potato in a potato salad, will attract and grow bacteria faster than any commercial mayonnaise will even begin to break down.

Also, dogs should never eat onions. Their stomachs cannot metabolize onions. Please remember it is dangerous to cut an onion and try to use it to cook the next day; it becomes highly poisonous for even a single night and creates toxic bacteria which may cause adverse stomach infections because of excess bile secretions and even food poisoning.

Please pass this on to all you love and care about. =====”


Honestly, after getting this email many times, it kind of unsettled my mind because like the majority, onions are part of our everyday cooking.  In fact, I don’t know of anyone who never uses onions.  I have never heard of anyone who got poisoned due to onions either.

While the email expresses a relative safety of  mayonnaise versus the other ingredients like onions and potatoes in homemade potato salad, the declaration on onions being poisonous can be quite alarming.

So I collated various information to put my mind at ease, hopefully yours, too; and shared this with my family as well.

To sum up:                                                                                                                                  

Variety of Onions (Photo Credit:  Docook)
Variety of Onions (Photo Credit: Docook)

– There’s no scientific basis for the old wives’ tale about onions used as a guard against the bubonic plague since the early centuries, during which  germs were not yet discovered. The assumption was that onions cleansed the air by trapping harmful odors, under the prevailing theory during those times  that contagious diseases were spread by miasma, or harmful air.

Whether it’s a folklore or not, there seems to be no harm if people prefer to follow the same precautionary measure with regards to “purifying the air”.  The important things is that, use of onions to clear the air does not poison people, right?

–  Nothing has been discovered to be a bacteria magnet yet.  If there was such, the medical community would have already grabbed it to draw bacteria away from sick persons.  It would have been a great medical breakthrough and pharmaceutical companies would have been racing for a patent.

– Nothing wrong with the onions; rather, it’s about how we handle them.  Slicing onions on contaminated boards, with dirty knives or blades, dirty hands, putting them in dirty wares, having a dirty fridge or exposing them to flies and insects would certainly make them contaminated.

– Cut onions contain enzymes which produces sulphuric acid that inhibits growth of germs (and that acid is also the culprit why our eyes become teary while we cut onions.!)  Bacteria prefers moist, neutral environment, and although there are some moulds which can tolerate acidic conditions and grow on onions, they are visible and not high risk.  We just have to cut those off or ditch that onion with moulds.

– Make sure to use pre-cut onions within two days, and pack them in zip-lock plastic bags, air squeezed out, then again, with a second bag before refrigerating; to avoid everything else in the fridge taste like onions.

– The surface of onions dries soon after cutting and does not support growth of bacteria.  (I cut onions and set them aside uncovered for two days; they just dried up, no moulds whatsoever.)

– We can safely put them in a plastic bag as storage and there won’t be any bacterial contamination. But, of course, using them freshly cut is always the best option.

–  No mention could be found on onions as the cause in any food poisoning case.

Other than for culinary uses, onions are used in many ways to help in healing:

  • as cure for athlete’s foot (a slice of onion rubbed on affected areas, two to three times daily, for at least two weeks)
  • to break down stubborn warts (dipping a slice of onion onion in salt and rubbing it on a stubborn wart (at least three times daily) will soften it and eventually break it down.
  • to soothe burning itches from mosquito bites and bee stings with an onion. (holding a slice of onion over the bite or sting relieves discomfort and itch and speeds up healing; repeating as necessary)
  • to clear a stuffy nose (using natural onion juice as a nasal decongestant; an onion chopped into small pieces and stirred in 1 to 2 tsp. of sugar, then set aside for about a half an hour, then strain juice. Drinking one tbsp. of juice three times a day for natural healing)
  • as an emergency eyewash to wash away eye irritants like a speck of dirt, an eyelash or other tiny objects (breathing the aroma of a chopped onion will get your eyes pouring and easily wash away the dirt with your tears)
  • as healing relief for an earache (Cutting a large juicy onion in half and placing the slice over an affected ear for 30 to 60 minutes can soothe pain. Not to  worry if a few drops of juice drop into the ear, as onion juice will help combat infection and inflammation)
  • to ripen boils and make them throw the pus out (Applying onion juice externally on boils encourages ripening; onion juice mixed with garlic juice in equal ratio can also bring beneficial outcomes)
  • to ease a toothache (a slice of raw onion or onion juice,  according to some researchers, can actually kill germs that cause tooth decay)

Moreover, many heart patients are now advised to eat raw onions (especially the red variety) after researches had shown that onions help increase blood circulation and reduce blood pressure; because they contain a natural chemical called adenosine which has been found to lower blood levels of LDL or whatv we otherwise know as bad cholesterol.

How not to cry from cutting onions:

To avoid painful eye irritation from the sulfurous fumes emitted by onions while they’re being cut or chopped, put your peeled onion in the freezer for more or less an hour before you cut it.  Make sure to use a sharp knife for cleaner cuts and less mashing.

If you’re in a rush to cook, leave the root end intact and cut the rest of the bulb first.  You may want to try wetting your forearms with water before you cut the onions.  See what works with you.  ^_^

The moral of that email:  Let us not be gullible to everything we receive or hear.  The best way to treat doubtful information is to check it out!  ^__^

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