Below message has been circulated on social media: 

Sample Message:

I-M-P-O-R-T-A-N-T.
ONIONS! I Had Never Heard This!!!
PLEASE READ TO THE END. Hope For Nigeria love healthy fans.

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.

LEFT OVER ONIONS ARE POISONOUS:
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 mayonnaise 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 home-made mayo) that spoils in the outdoors. It's probably the ONIONS, and if not the onions, it's the POTATOES.

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 SHARE this for the Benefit of those your love and
care about.

Our Analysis -

The above message states that using cut onions that have been stored is dangerous because they attract bacteria. It looks like it is waste and fake message being spread on social media.

Therefore, the message saying cut onions become toxic is a hoax, left over, cut onions are not poisonous, they are safe to use when stored in hygienic conditions. There have been many other versions of this story, claiming that leaving onions around a room will absorb the flu virus along with bacteria causing other illnesses and will prevent people from becoming sick. It is a fact that onions were used in folk medicine long before 1919, but it is just a false belief, there is no scientific evidence to prove it. Onions are not bacteria magnets, they are good to use, especially because they are high in vitamin C and are a good source of fiber and other important nutrients.

Following was published in https://www.onions-usa.org/faqs/onion-flu-cut-myths :

Q: Are cut onions or leftover onions poisonous?

A: When handled properly, cut onions are not poisonous. After being cut, onions can be stored in the refrigerator in a sealed container for up to 7 days.

A widely circulated claim states uncooked, leftover onions are 'poisonous' because they're 'a huge magnet for bacteria,' thus likely to spoilage.

This claim stems from a blog post that dates back to March 2008. While the original post was removed from the internet in 2009, part of that post continues to circulate the internet.

For more information about the false nature of this claim, please read the attached consumer letter from the National Onion Association.

Conclusion -   The above message can be termed as fake and irrelevant based on the details given in the analysis section.

About The Author

Chetan Sharma is an Indian fact-checker and news writer, writing news for Ayupp since 2014.

You Might Be Interested In

Latest On Ayupp.com