Sara Baker says the light went on in her head after a cup of hot cocoa set off a storm in her stomach.
"I went back and looked at the package, and there it was: carrageenan," said Baker, a career services coordinator from Bloomington, in central Illinois.
Baker had been taking medication for ulcerative colitis for years but still suffered debilitating digestive flare-ups without warning. She had read warnings about carrageenan in a natural health newsletter but didn't take them seriously. After all, researchers haven't conclusively linked the common food additive to gastrointestinal problems in humans.
This time, though, "it really clicked," she said. "It took awhile to learn just how many things it's in, but now that know, I can avoid it, and I no longer have the problems."
Experiences like Baker's have led some people with gastrointestinal problems to sidestep mainstream medical advice and avoid carrageenan, a seaweed-derived texturizer found in meat, dairy and other processed foods — including some organic products.
For scientists, however, these are just anecdotes. Though studies on lab animals and human cells have suggested that carrageenan can cause gastrointestinal inflammation, many researchers and physicians say it's unclear whether the additive has the same impact on people who consume it.
"I believe it's worth investigating and doing the science to find out," said Dr. Stephen Hanauer, a medical professor and chief of gastroenterology and nutrition at University of Chicago Medicine.
His co-researcher, UIC physician and professor Joanne Tobacman, has been looking at the health effects of carrageenan for more than a decade and is concerned enough to have petitioned the U.S. Food and Drug Administration in 2008 to prohibit the use of carrageenan in food.
Her petition cited decades of publicly funded, peer-reviewed science — including her own — on carrageenan-induced inflammation in animals and cells. In June, the FDA responded with a letter of denial.
Tobacman said "it was disappointing that, with such clear evidence about the effects of carrageenan on inflammation, the FDA did not restrict the use of carrageenan, particularly in infant formula." Europe doesn't allow the ingredient in formula.
The additive, which lends a uniform, creamy texture to food, can be found in soy milk, yogurt, ice cream, cheeses, some meats, diet soft drinks and even toothpaste.
Michael Adams, deputy director of the FDA's Office of Food Additive Safety, said the petition didn't make a compelling case to re-examine the safety of carrageenan. "It has been reviewed repeatedly by FDA scientists and other international organizations, and in the judgment of those experts there hasn't been a problem," he said.
Adams called a rat study from 2006 "the gold standard for us because it exactly mimics the exposure consumers are going to get when they eat these carrageenan-containing foods."
That study was funded and performed by a manufacturer of carrageenan. Adams said he didn't know that but added: "If you look at the science and you believe it's well done, it doesn't matter where the money comes from."
The Cornucopia Institute, a Wisconsin-based organic industry watchdog group, was expected to release a report Sunday night on carrageenan called "How a Natural Food Additive Is Making Us Sick."
Charlotte Vallaeys, Cornucopia's director of food policy, said the group felt "an ethical obligation" to raise awareness. "If government agencies weren't going to protect consumers, then it seemed we needed to let consumers know about this so they could protect themselves."
The institute also is challenging the FDA's denial of Tobacman's petition. Among other objections, Cornucopia's letter to the agency asks why officials didn't consider any studies on carrageenan published in the last four years.
Adams said the FDA's scientific evaluation in response to the petition was finished in May 2009, after which it spent more than three years in what he calls the "administrative chain."
Regarding infant formula, Adams said, Europe takes a different approach to food additives than the U.S., sometimes banning a substance when toxicity studies raise concerns but aren't conclusive. "The Europeans do their business that way, but we don't," he said. "We would base it more on the science we have rather than waiting for science to be developed."