Earlier this winter, a handful of complaints started showing up on a consumer crowdsourcing website claiming Lucky Charms cereal was causing gastrointestinal distress.

The New York Post ran a story on April 1 based on those self-reported claims, with the headline "Lucky Charms cereal causing vomiting, diarrhea."

As the story spread — all the way to a "Saturday Night Live" joke on "Weekend Update" — thousands more complaints poured onto the consumer site, iwaspoisoned.com. The U.S. Food and Drug Administration said Tuesday it is investigating about 100 reports made directly to the federal agency.

But so far, General Mills and the FDA have not found a link between Lucky Charms and sickness.

"I'm skeptical," said Ryan Osterholm at OFT Food Safety & Injury Lawyers in Minneapolis. "The FDA and General Mills are doing what they should do, and nothing I've seen so far indicates there's something going on. But you never know."

Golden Valley-based General Mills says it looked at its manufacturing facilities and found nothing that would prompt even a cautionary recall.

"We have investigated claims from a variety of sources — those made on the internet, through media inquiries, and directly to us and the FDA. To date, we have not found any evidence of consumer illness tied to our products," a General Mills spokeswoman said in a statement.

The company declined to provide specifics of how it came to the conclusion the cereal was not tainted or causing sickness.

On Wednesday, the FDA announced it had launched an on-site investigation. "Although FDA has not determined that this cereal is linked to these adverse event reports, FDA is conducting an investigation to determine the potential causality of these complaints," the agency said.

General Mills issued a global responsibility report this week stating its ingredients are traceable and suppliers regularly audited, "which is key to isolating risks in the event of food safety concerns." In 2021 the company had one recall of soup; there were two recalls in 2020.

Food safety expert Jill Stuber said manufacturers typically have protocols they follow when looking into concerns and will gather as much information as possible from consumers.

"Do we actually have evidence and can we find it again?" said Stuber, of Minnesota-based food safety consultancy Catalyst LLC. "In one plant you might look to see if complaints are coming in around a certain time period — that's why we keep all these records. It's really going through there and asking, 'Is there anything unusual that happened that day with preventive controls, sanitation, critical control points?'"

An FDA spokesperson said all consumer complaints are taken seriously, regardless of their origin.

"Complaints of a less serious nature or those that appear to be isolated incidents are monitored and the information may be used during a future inspection of a company to help the FDA identify problem areas in a production plant," the agency said.

General Mills sells upward of 100 million boxes of Lucky Charms in the U.S. per year, according to Chicago-based market research firm IRI — that averages out to more than 270,000 boxes a day.

With such a widely distributed product, Osterholm said, it's important to question causation vs. correlation.

"At any one moment in time there's a small percentage of Americans with gastrointestinal illness," he said.

An increasing number of people will attribute that distress to a product the further the rumor spreads.

"It starts to gain speed: 'I heard about this, I ate Lucky Charms, I got sick,'" Osterholm said. "From an epidemiological standpoint, it's not very compelling, but it is worth investigating."

The Lucky Charms saga hearkens back to last year's online furor over another General Mills cereal — hardened sugar clumps in Cinnamon Toast Crunch.

"There's an outrage machine, and that's one of those big cultural things as a food manufacturer or marketer you have to keep in mind, because you will be held to a higher standard," said Vivian Martin, a marketing professor at the University of Minnesota and a former General Mills vice president.

Martin said she would be "shocked" if an issue was discovered, but she encouraged General Mills to be as transparent as possible to reassure consumers.

"As I tell my students, it doesn't matter what you've done, it matters what people think you've done."