How To Debunk Food Warnings

Don’t let a black cat cross your path. Don’t walk under a ladder. Throw salt over your shoulder if you spill it.

We’ve all heard these old-wives’ tales, and we mostly know they’re a load of … manure. But when we get something from a friend via email, and it’s warning us about the deadly threat of leftover onions, with references to actual scientists who have confirmed it … well, now it’s starting to sound like something we should maybe listen to.


But on the other hand, we should be careful about listening too quickly to advice like this. Because with food warnings, it’s not just some vague “bad luck” we’re in for if we listen to the wrong advice. We could actually stop eating healthy food for no good reason. Or start doing things that are bad for us. Or stop taking reasonable precautions because we think we’re covered by a “natural remedy”.

I saw it in an email, it must be true!

When urban legends entered the email age, they started growing “proof” like a bad fungus. Now it’s not “my brother’s college roommate saw this happen”. It’s “Ed, a food chemist at Mullins Food Products”. Now that sounds official, doesn’t it? Problem is, Mullins never heard of Ed. And the warning that’s supposedly based on what Ed said? It’s not true.

This post started when someone sent me an email with a warning about keeping leftover raw onions. Supposedly onions absorb bacteria out of the air, so they’re one of the worst things you can keep. As a matter of fact, they’re so good at drawing bad things out of the air that you can place onions in the room and they’ll keep you from getting the flu. You can even put a sliced onion next to someone who already has the flu and it will suck the infection right out of them!

That’s exactly the kind of “traditional wisdom” I love to pass on. Tips that you’ll never hear from big business because there’s no money in it for them. Except that none of that stuff about onions is true!

When it doubt Snope it out

Snopes.com keeps copies of all the warnings that get circulated around the internet, and they do the research to see if it’s true or not. They had both emails with the onion myths. The first was about onions preventing the flu, and the second saying that cut onions are too dangerous to keep around.

You can go read all the references for yourself, but here’s the short version:

  • Yes, you’re more likely to get sick from onions than from the mayonnaise in the potato salad. Although it won’t be the ones in the potato salad, but the diced onions on the hot dog condiment table getting you sick.
  • Most likely is that it’s the potatoes that get you sick. Of all the ingredients in potato salad, it’s the potatoes themselves that are the best home for bacteria.
  • No, onions don’t do anything to prevent the flu.

Lots of things you get via email will sound kind of reasonable. But most of it — and I’m not exaggerating when I say “most” — has been around for a long, long time. Snopes will tell you where most of these stories came from, with references. And yes, they tell you which ones are true, too … because some of them are.