Sean Adl-Tabatabai - An official study published last month in BMC Medicine reveals that carrageenan, a common additive in processed foods, causes damage to the lining of the small intestine and the body's ability to process blood sugar.
This damage can lead to serious chronic conditions such as Crohn's disease and Type 2 diabetes and cardiovascular disease.
The Defender reports: "Our study performed in healthy young men is unique as it indicates that already a short-term and moderately increased intake of carrageenan may have pro-inflammatory effects in the gut in humans, which can particularly lead to metabolic problems in those being overweight," says lead author Dr. Robert Wagner of the German Diabetes Center.
The study adds, "The results warrant caution with carrageenan-containing foods, especially in individuals who are prone to develop type 2 diabetes."
Previous studies have shown that carrageenan has similar effects in animals. Studies have also suggested direct associations in humans between type 2 diabetes, cardiovascular disease and cancer and exposure to various food additives widely used in ultra-processed foods.
Research has also shown that removing carrageenan may improve insulin signaling and glucose tolerance.
In this study, researchers found in lab tests with 20 men that moderate intake of carrageenan in those with higher BMI can weaken the lining of the small intestine, most likely due to pro-inflammatory mechanisms in the gut. It may also contribute to insulin resistance.
A weakened intestinal lining is significant because it reduces the protective mucus layer and allows toxins into the bloodstream (intestinal permeability, or "leaky gut"). Intestinal permeability is associated with chronic diseases of the intestine, such as inflammatory bowel disease, including Crohn's disease and ulcerative colitis.
"Our investigation suggests that the consumption of carrageenan, similar to what has been observed in animal studies, can impair the barrier function of the intestine," says Wagner.
"This could have long-term health consequences and increase the risk of inflammatory diseases."
Researchers found participants with higher BMI showed a reduction in the effectiveness of the hormone insulin, which lowers blood sugar (glucose). That can lead to problems with how the body processes energy to function (metabolism), says Wagner.
Those with higher BMI who had higher carrageenan intake also showed markers of increased inflammation in the blood and hypothalamus -- the brain region that helps regulate sugar metabolism and appetite.
Carrageenan (pronounced ker-ah-ghee-nen) is an FDA-approved food additive, also known as E407, that is derived from red seaweed and consists of large sugar molecules.
It is increasingly used to thicken, blend or stabilize foods, especially dairy products and ultraprocessed foods, to improve their texture and extend their shelf life. Carrageenan also serves as a fat substitute in some low-calorie and low-fat products.
To gauge its impact on human health, the researchers ran a series of tests to measure different aspects of metabolism, insulin sensitivity, and gut health. They specifically looked at its effects on liver fat, body fat distribution, blood sugar levels, gut bacteria and inflammation markers.
Study participants included only men who did not have higher weight, obesity or chronic disease. They were given either a placebo or carrageenan in addition to their normal diet, in an amount roughly equivalent to two to three times the daily dose consumed in the U.S. Both groups were observed over two weeks between October 2015 and December 2016.
Because gut barrier problems are more common in people with a high-fat diet, high blood sugar or obesity, the effects of carrageenan on glucose metabolism and inflammation may have been harder to detect among study participants, the researchers say.
In addition, only young, healthy men participated, so results may not apply to older or less healthy groups, the researchers note. The study also did not see potential longer-term metabolic effects.
Understanding food additive harms
Choosing minimally processed foods and reading labels can help reduce exposure.
"Our data support that the reduction of carrageenan intake is important," Stefan says.