Researchers have come up with a surprising new theory on what’s helping make people not only fatter, but also more prone to obesity-related diseases such as diabetes and inflammatory bowel disease.
They’re pointing the finger at emulsifiers — ingredients used in processed foods to help make them creamy and keep them mixed. Think mayonnaise, which is held together by nature’s emulsifier — the lecithin in egg yolks.
But some of the emulsifiers used in foods have a chemical structure similar to detergent, said researchers Andrew Gewirtz and Benoit Chassaing of Georgia State University. They found evidence that at least some commercial emulsifiers might mess up the balance of “good” germs in the gut, promoting the inflammatory processes that underlie obesity-linked diseases such as diabetes.
“A key feature of these modern plagues is alteration of the gut microbiota in a manner that promotes inflammation."
They might even help cause people to overeat in the first place, the two say in a report published in the journal Nature.
Inflammatory bowel disease, a family of ills that include Crohn’s disease and ulcerative colitis, affect millions. Metabolic syndrome includes the various measurements associated with diabetes and heart disease — high blood sugar, high blood pressure, too much abdominal fat and unhealthy cholesterol levels.
Both are on the rise. “A key feature of these modern plagues is alteration of the gut microbiota in a manner that promotes inflammation,” Gewirtz said in a statement.
The theory is that these chemicals, designed to hold little globs of fat in place in a liquid to keep them from floating to the top, can disrupt the mucus that lines the gut. That, in turn, can cause inflammation and maybe allow "good" germs to leak out.
They tested their theory by feeding mice two such emulsifiers: polysorbate 80 and carboxymethylcellulose.
Several different experiments showed that feeding the mice these products changed the balance of germs living in their digestive systems. Mice genetically prone to bowel diseases developed chronic colitis, they reported. Normal mice developed mild inflammation of the intestine and metabolic syndrome.
The normal mice also started overeating.
Researchers not involved in the study said they’ll need more evidence to be convinced.
“This in interesting research in colitis-sensitive mice but the amount fed to generate the effect (1 percent of food or water intake) were massive doses far, far beyond the amount we could take in our usual diet,” said Catherine Collins, a dietician at St George's Hospital in London.
“The fat, sugar and calories provided by ice-cream are far more likely to contribute to weight gain than trivial amounts of these additives,” agreed Tom Sanders, professor emeritus of nutrition at King’s College London.
“The fat, sugar and calories provided by ice-cream are far more likely to contribute to weight gain that trivial amounts of these additives."
But Gewirtz said the point is these additives may cause the overeating in the first place. Several studies have suggested that different populations of gut microbes can affect appetite.
“We do not disagree with the commonly held assumption that over-eating is a central cause of obesity and metabolic syndrome,” he said in a statement.
“Rather, our findings reinforce the concept suggested by earlier work that low-grade inflammation resulting from an altered microbiota can be an underlying cause of excess eating.”