False
Facebook posts
"If you’ve been exposed to the stomach flu," you can avoid getting it if you "drink 3 glasses of 100% grape juice a day for 3 days. It changes the acidity in your stomach. ...This really works!!"

Facebook posts on Friday, January 10th, 2020 in a Facebook post

Grape juice keeps you from getting sick, even after exposure to stomach flu? We wish

How not to get the stomach flu — even after you’ve been exposed to it?

Simple answer, says the Incredible Recipes Facebook account, which has attracted nearly 7.8 million followers over seven years.

"If you’ve been exposed to the stomach flu drink 3 glasses of 100% grape juice a day for 3 days," its post on Facebook says. "It changes the acidity in your stomach. ...This really works!!"

Not getting the flu after going on that regimen, of course, doesn’t mean the juice stopped you from getting sick.

But is there evidence that grape juice prevents the stomach flu — after exposure?

This post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

In the past couple of years when this claim has surfaced, often on cooking and parenting websites, it was knocked down as unproven in articles by the New York Times, Slate, Men’s Health and the fact-checking site Snopes.

Unfortunately for flu sufferers, we found the same.

The stomach flu is a "very contagious virus," with its vomiting and diarrhea, and occurs an average of 19 million to 21 million times per year, according to the federal Centers for Disease Control and Prevention. "People with norovirus illness can shed billions of norovirus particles. And only a few virus particles can make other people sick," the CDC says.

Leading health authorities such as the Mayo Clinic and the CDC each offer a handful of tips on how to avoid getting the stomach flu. But no mention of grape juice.

Why not?

Like the experts in the other articles, Baylor College of Medicine professor Mary Estes and Ming Tan, a professor in the division of infectious diseases at Cincinnati Children’s Hospital Medical Center told us there is no scientific evidence to back the grape juice claim.

Stomach flu is normally caused by a virus infection that occurs in the intestinal tract, not in the stomach, and drinking grape juice will not change the acidity of the stomach anyway, Tan told us. 

He added: "Exposure to stomach flu bugs does not necessarily lead to stomach flu because some factors, like your blood type, can affect the attachment of the bugs to your intestinal cells. This explains why only (some) people get sick in a stomach flu outbreak even if everyone has been exposed."

Moreover, said University of Iowa professor of internal medicine and epidemiology Eli Perencevich, once exposed "you get sick 12 to 24 hours after, so the three-day day thing is another dubious claim."

Our ruling

A Facebook post says:  "If you’ve been exposed to the stomach flu," you can avoid getting it if you "drink 3 glasses of 100% grape juice a day for 3 days. It changes the acidity in your stomach. ...This really works!!"

This claim surfaces periodically but experts say there is no scientific evidence to back it up.

Our rating is False.