I hope everyone had a wonderful and delicious Thanksgiving! Today, I’m continuing my series on common food additives.
Last time, I discussed the health effects of carrageenan, a food additive that is commonly used as a stabilizer, thickener, or emulsifier. Another additive that shares many of these functions in commercial foods is xanthan gum, which is also popular in gluten-free baked goods for the elasticity it lends to dough.
Although it isn’t as heavily discussed in the blogosphere as the other additives I’ve covered thus far, many health-conscious people see it on ingredient lists and wonder what it is, and whether they should be eating it. In this article, I’ll do my best to answer those questions.
Xanthan gum is a largely indigestible polysaccharide that is produced by bacteria called Xanthomonas Camestris. (1) Manufacturers place the bacteria in a growth medium that contains sugars and other nutrients, and the resulting product of bacterial fermentation is purified, dried, powdered, and sold as xanthan gum. (Makes you wonder who first thought to put it in food, doesn’t it?)
Overall, the results from animal studies on xanthan gum aren’t very concerning. In one experiment, rats were fed xanthan gum for two years in concentrations of 0.25, 0.50 or 1.0 g/kg body weight per day. (2) The only notable difference between the xanthan gum groups and the control group was that rats fed xanthan gum experienced soft stools somewhat more frequently than the control rats, but even that barely reached statistical significance. There were no differences in growth rate, survival, blood markers, organ weights or tumor incidence.
Another experiment followed a similar design but used dogs instead of rats, and the results were the same: no changes other than occasional soft stools. (3) In a three-generation reproductive study, rats were fed either 0.25 or 0.50 g/kg per day, and there were no significant changes in the parents and offspring from the xanthan gum-receiving groups. (4)
Based on those initial studies, it was concluded that xanthan gum is a perfectly safe food additive. Since then, a few additional animal studies with different aims have been published.
One study, conducted to evaluate the effects of xanthan gum on digestion in rats, found that a diet containing 4% xanthan gum increased the amount of water in the intestines by 400%, and also increased the number of sugars remaining in the intestine. (5) Another study found that in rats fed 50 g/kg of xanthan gum (an incredibly high dose) for 4 weeks, the stool water content and short-chain fatty acid (SCFA) content increased significantly. (6)
This last study actually relates to the potential anti-tumor properties of xanthan gum, and researchers found that orally administered xanthan gum was able to slow tumor growth and prolong the survival of mice with melanoma. (7) The mechanism is unclear, but it’s interesting nonetheless.
Due to the lack of harmful effects observed in animal studies, there are few human studies on xanthan gum. The first study aimed to determine the safety of xanthan gum when consumed by humans in an everyday dietary setting, but at levels much higher than people would normally encounter in their diet. (8) For 23 days, 5 adult men with no GI issues consumed between 10.4g and 12.9g of xanthan gum daily (based on the subjects’ weight), which is 15 times the current Acceptable Daily Intake of 10mg/kg. Overall, they experienced a reduction in serum cholesterol, an increase in fecal bile acid, and an increase in stool output and water content.
Another study had volunteers consume 15g of xanthan gum per day for 10 days. (9) They found xanthan gum to be a “highly efficient laxative,” and subjects experienced greater stool output and gas. That’s not very surprising considering the high dose, but what I found particularly interesting about this study was their measurement of the ability of subjects’ fecal bacteria to metabolize xanthan gum.
The researchers found that before the trial period, bacteria from the stools of only 12 of the 18 subjects could break down the xanthan gum, while after the trial period, bacteria from 16 of the subjects could break it down. (10) Additionally, the stool samples containing bacteria that could break down the xanthan gum showed a much greater production of hydrogen gas and SCFA after the trial period as compared to baseline, indicating that the intestinal bacteria of the subjects quickly adapted to this new food source. Clearly, xanthan gum (like many indigestible carbohydrates) can have a profound impact on the gut microbiota in large doses.
Colitis in Infants
The only concerning research I found on xanthan gum relates to the development of necrotizing enterocolitis (NEC) in infants. Earlier this year, the New York Times published an article relating the tragic deaths of infants who had developed NEC after consuming a diet of formula or breast milk that had been thickened with a xanthan gum-based product called SimplyThick. This product was widely used in hospitals to thicken feed for infants with swallowing difficulties.
Two papers reviewed the cases of xanthan gum-associated NEC, and while there isn’t enough data to establish causation, the general consensus seems to be that the xanthan gum caused increased bacterial production of SCFA in the newborns’ intestines, and this contributed to the development of NEC. (11, 12) Although SCFA are vital to colon health, the immature digestive systems of newborns appear to be extremely sensitive to them. (13, 14) Since then, general practice guidelines suggest avoiding manufactured thickening products in babies under 12 months old, and rice cereal or baby oatmeal is used instead.
I wanted to address this because while it’s clearly important to avoid giving xanthan gum to infants (especially in large amounts), I’d like to emphasize that none of this changes the fact that xanthan gum appears to be relatively harmless in adult humans. None of the animal or human studies found damage to the intestinal mucosa following xanthan gum consumption, even in large doses, so this danger appears to be unique to newborns. For everyone else, SCFA aren’t something to be afraid of, and they are actually beneficial for the gut and for metabolic health, as I mention in previous articles here and here.
Wheat, Corn, Soy, and Dairy Allergies
I mentioned in the opening section that xanthan gum is produced by bacterial fermentation of a sugar-containing medium. Unfortunately, that ‘medium’ is often a potentially allergenic substance such as corn, soy, dairy, or wheat. Many xanthan gum manufacturers aren’t eager to share what their ‘medium’ is, but one common supplier, Bob’s Red Mill, discloses their production practices.
It looks like they originally used corn or soy as a medium, but they’ve since changed their medium to a glucose solution derived from wheat starch. However, they claim that the xanthan gum is still gluten-free, and it continues to be marketed as such.
It can be difficult to find production info online, but just be aware that if you have a severe allergy to corn, soy, wheat, or dairy, it would be prudent to either avoid xanthan gum entirely or check with the manufacturer to see how it’s produced.
Based on the available evidence, the worst xanthan gum seems to be capable of (in adults) is causing some digestive distress in those who are susceptible by increasing stool bulk, water content, and sugar content. But as I just mentioned, those with severe allergies should also be careful.
I recommend that people with digestive problems generally avoid xanthan gum, not because there’s evidence that it could damage your gut, but because its structural properties make it likely to produce unpleasant gut symptoms. Unlike carrageenan, there’s no evidence that xanthan gum can cause serious harm (even in human studies using doses much higher than people would normally encounter), so if you are able to tolerate it, I see no compelling reason to strictly avoid it. I wouldn’t recommend consuming large amounts every day, because xanthan gum appears to have a high propensity for altering the gut microbiome, and it’s unclear whether that alteration could be problematic in the long run. But the small amounts that you would normally encounter in the context of a real-food diet shouldn’t present a problem.