Carrageenan, when used as an ingredient, may keep chocolate from separating from the milk in chocolate milk.

Design issues arise in carrageenan studies

Myra L. Weiner, Ph.D., a board certified toxicologist, has published studies on carrageenan that date to the late 1980s. She worked for 29 years at FMC Corp., Philadelphia, and now serves as president of TOXpertise, L.L.C., Princeton, N.J.

Over the decades Dr. Weiner has noticed flaws and misleading information in carrageenan studies. She provided details on study flaws, along with guidance on better ways to conduct studies, in a paper entitled “Parameters and pitfalls in the conduct of food additive research, Carrageenan as a case study.” It appeared on-line Nov. 23, 2015 in Food and Chemical Toxicology. FMC Corp. provided funding.

Here are some ways that carrageenan studies may go astray, according to Dr. Weiner’s paper:

Bad cells: Cell-based models have been used in carrageenan studies, but tumor-derived cell lines may differ from normal tissues. Many in vitro studies of carrageenan have used the NCM460 cell line. As early as 2007, INCELL, the provider of NCM460 cells, reported the cell line might be tumorigenic. At least 12 in vitro studies used the NCM460 cell lines between 2007 and 2015.

“Just from a scientific point of view, it makes sense to look at those studies again in light of the change of the cells,” Dr. Weiner said. “That may change the conclusion, but that is really up to the journal and the authors of those papers (to re-evaluate the studies).”

Poligeenan vs. carrageenan: Poligeenan also has been called degraded carrageenan. Poligeenan has different molecular weights, physical/chemical properties and toxicological properties than carrageenan, but some studies have confused the two.

“It has been an issue for a while and has created misconception in social media and in the literature, and that’s because some researchers may be using poligeenan, or the old term was degraded carrageenan, but called it carrageenan,” Dr. Weiner said. “If you read the description, you have to dig down to what is actually said in a paper, and if you read the description of their test material, you will see that it was possibly the degraded form, which is a different toxicity and has different properties.”

Regulatory agencies such as the Food and Drug Administration and the World Health Organization only permit food grade carrageenan in food. Carrageenan suppliers provide certificates of analysis.

Consumption of carrageenan: It is important to have animal study designs mimic the use being evaluated. Carrageenan remains bound to protein in diet, milk, infant formula and liquid nutritional supplements. In animal studies, it will bind to protein in rodent chow.

In some animal studies, however, carrageenan was added to drinking water and thus did not bind to protein. These studies do not model humans’ exposure to foods and beverages with carrageenan.

Other studies have found carrageenan caused swelling or inflammation when injected into rats’ paws.

“If you inject it, yes, you will get a response,” Dr. Weiner said.

However, eating carrageenan will not cause swelling/inflammation, she said.