Does Carrageenan Cause Cancer?

If you haven’t heard about the controversy regarding carrageenan, then you’ve missed out on yet another food panic. Carrageenan is used as a thickening agent in a wide variety of foods, including organic food and baby food. If it causes inflammation, and has been linked cancer, then that’s a problem we should all be concerned about. Especially if it’s an additive to health foods like Stonyfield, Dean Foods, Hain Celestial, etc.

Carrageenan is extracted from red seaweed, which is good. But its manufacturer uses solvents to extract it and those solvents may stay in the finished product, which is bad.

Carrageenan can also be degraded into another compound in the gut, poligeenan. As far as I know, no one is defending poligeenan. According to critics, poligeenan clearly causes inflammation and is used in animal studies to test anti-inflammatory drugs. The question is whether carrageenan becomes poligeenan in the human gut. Carrageenan is made using alkaline solvents, while poligeenan is produced from the same seaweed using acid solvents. It’s an understandable concern that carrageenan is converted to poligeenan in the gut by the stomach acid. Even if it doesn’t convert, the carrageenan may be contaminated before it gets into us: “even the carrageenan manufacturers have no reliable way of determining the levels of contamination with degraded carrageenan (poligeenan) in their food-grade products.” (Cornicopia Institute report)

The basis of the push to ban carrageenan comes from the Cornicopia Institute, a watchdog group for family farms. They published a report on carrageenan in 2013 which states: “Animal studies have repeatedly shown that food-grade carrageenan causes gastrointestinal inflammation and higher rates of intestinal lesions, ulcerations, and even malignant tumors.” (complete report here)

Sounds like we should definitely ban this thickener, particularly as: “carrageenan adds no nutritional value or flavor to foods or beverages.” (Cornicopia institute report). In looking at the scientific studies presented by the Cornicopia Institute dating back to the 1960s, I found several things.

First, if you’re a guinea pig or a rat, carrageenan is bad for you. We’ve shown this since the 1960s, as well as showing that carrageenan did not do the same things to squirrel monkeys, hamsters, or ferrets.The rats also got tumors from eating too much carrageenan. Second, everyone who did a study that says that carrageenan is good has ties to carrageenan manufacturers and should be ignored. Third, Tabacman et al., think that carrageenan is really bad for you, causing inflammation and cancer in human gut cells. They are the only group who’ve done their studies. Although they are funded by the NIH, I’d like to see another independent group repeat their studies.

If you believe the manufacturers, there’s no truth in these claims. A review says: ” Dietary CGN has been shown to lack carcinogenic, tumor promoter, genotoxic, developmental, and reproductive effects in animal studies. CGN in infant formula has been shown to be safe in infant baboons and in an epidemiology study on human infants at current use levels.” (review here)

Then, I always think it is wise to go looking on my own. Here are some studies I found myself. When I did so, I suddenly wondered why these studies weren’t discussed in the Cornicopia report. Sure, maybe these are all by carrageenan manufacturers, but it’s worth mentioning that carrageenan might not be all bad.

I have to start this off with an abstract quotation: “Red seaweeds are popular and economically important worldwide and also well known for their medicinal effects due to the presence of phycocolloids. Carrageenans, the major phycocolloid group of red algae, have been extensively investigated for their vast array of bioactivities such as anticoagulant, antiviral, cholesterol-lowering effects, immunomodulatory activity, and antioxidant. Carrageenan possesses promising activity both in vitro and in vivo, showing promising potential to be developed as therapeutic agents” (abstract here).

So, what if the initial claim against carrageenan, that it has no value in the human diet, was false? What if it did have some possible value?

OK, now we start down the rabbit hole. It turns out that not all carrageenan is created equal. We’ve got all sorts of carrageenan from all sorts of species. How am I supposed to know if the carrageenan in a particular study is the same sort of carrageenan that is used as a food additive?

Then, looking for clarification, I find that food additive carrageenan also has a variety of species and properties. That enticing literature is here. But, using those additive species as a guide, I can find some information on carrageenan. Here are some things that the Cornicopia Institute didn’t say about carrageenan.

“We also review data obtained using animal models that demonstrate the potency of carrageenan and chitosan as antiendotoxin agents” (here)

“the antiviral actions of the sulfated polysaccharides derived from marine algae including carrageenans, alginates, and fucans” (here)

“carrageenans, fucoidan, sesquiterpene hydroquinones, and other classes of compounds with anti-HIV activity” (here)

carrageenan and ulvan biopolymeric gels, that have been proposed for engineering cartilage” (here)

On the one hand, we have the Cornicopia Institute and an NIH researcher saying that carrageenan is basically poison. On the other hand, we have studies that say carrageenan might be very useful and healthy. Who do we believe?

In the Cornicopia report, a range of anecdotal reports from a survey they produced feature prominently. The individuals in the survey experienced a relief of their symptoms by discontinuing carrageenan-containing products. While these people got better, this doesn’t make me want to ban carrageenan. Avoiding it seemed to do the trick for these people. And I’m left with the sense that those who avoided carrageenan and didn’t have resolution wouldn’t be likely to be writing in.

The researcher, Tabacman, is presented by the Cornicopia Institute as truly independent and without an agenda. But a quick glance at the literature shows Tabacman is not satisfied with carrageenan in the diet causing colon cancer. She goes so far as to hypothesize that carrageenan intake is responsible for the increases in breast cancer. (here) Now, I’m willing to think about carrageenan causing diabetes, colon cancer, and a host of GI problems, but I’m having a little difficulty with directly linking it to what is known as primarily a hormonal cancer. Tabacman bases her hypothesis on the idea that carrageenan “undergoes acid hydrolysis to poligeenan” in the human body and then finds its way to the breast tissue.

So, if we accept that all other researchers are on the take and just out to get the poor consumer based on what the Cornicopia Institute says and Tabacman confirms, how can we look for any other point of view?

Surely the answer lies in our meat crop. While we might assume that consumers can eat whatever they want, anything that threatens our meat crop costs dollars and must be avoided. So we might possibly trust reports on whether baby pigs destined for slaughter into bacon benefit from carrageenan or get sickly on the terrible stuff. First, the researchers tested whether carrageenan degraded in the pig formula. It did not. (here) Next, they tested the plasma of the baby pigs. All the baby pigs did have some level of poligeenan (the degraded, bad form of carrageenan). It ranged from 10 micrograms to 100 micrograms per milliter. As the pigs were not fed any poligeenan, this was the conversion rate for baby pigs. (here) So even if we accept that consumers are being hoodwinked by big agribusiness, the reality is that the likely conversion rate of carrageenan to poligeenan is very low.

I’m not convinced that carrageenan has no value, because there are studies that it might. I think that if there’s a problem, it would be in the degraded form of carrageenan (poligeenan) that causes cancer, not the food grade itself. I haven’t seen the studies that show me that most of those testing have checked the levels of poligeenan in the study subjects’ blood like the farmers did with the baby pigs.Since we don’t know how much poligeenan is being eaten mixed into the carrageenan, carrageenan should likely be more closely monitored for poligeenan content. While Tabacman is convinced the conversion takes place between carrageenan and poligeenan, the only data I have that she didn’t do herself says this happens at a very low rate. She’s right, but it may not be enough to matter.

Which brings me back to the Cornicopia Institute’s report. As a watchdog for family farming, I wonder if they’ve ever looked into how carrageenan is farmed? Here’s the FAO summary quote: “Thanks to attributes such as relatively simple farming techniques, low requirements of capital and material inputs, and short production cycles, carrageenan seaweed farming has become a favourable livelihood source for smallholder farmers or fishers and generated substantial socio-economic benefits to marginalized coastal communities in developing countries.” (here)

So banning carrageenan shuts down small family farms around the world. Not really a great outcome. As for carrageenan research, while Cornicopia tries to make an open and shut case, medline only lists seven entries for poligeenan. I couldn’t find even a toxicology report on the stuff. Before we ban a different substance that has a variety of species and a wide variety of forms, I think it’s valid to do some testing on the levels of degradation into poligeenan found between the different species. It may well be that one or two forms of carrageenan are more likely to degrade into poligeenan while other forms may not.

In the meantime, many manufacturers are shifting to other thickening agents. I’m not sure that’s going to be any better in the long run, as we don’t have the same history and level of research on those products either.


2 Replies to “Does Carrageenan Cause Cancer?”

  1. Do you know anything about Japanese Honeysuckle as a supposedly natural preservative? It’s an ingredient in some of my favorite skin/hair/makeup products and I’ve read that it’s not actually natural or that it’s not actually what it says it is? I can’t make sense of any of it and I’m not sure if I should be concerned. If you know anything about it, I’d appreciate your perspective.

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