Guar, xanthan, carrageenan: the gums in healthy foods, explained

Pick up a carton of almond milk, a tub of dairy-free yogurt or a loaf of gluten-free bread, and there's a good chance the ingredient list includes a gum. Often more than one.

These ingredients are used in small amounts to make foods thick, smooth and stable. Several of them are types of fiber. A few have raised research questions. Here's a plain guide to what they are and what the human studies show so far.

What gums and emulsifiers do

Without them, plant milks separate in the carton, gluten-free bread crumbles and low-fat yogurt turns watery. Thickeners and stabilizers hold water and give texture. Emulsifiers keep fat and water mixed. The names you'll see most often:

• Plant and microbial gums: guar gum, locust bean gum, xanthan gum, gellan gum and gum arabic, also called acacia gum.
• Seaweed extracts: carrageenan, agar and alginate.
• Modified cellulose: cellulose gum, also listed as carboxymethylcellulose or CMC.
• Emulsifiers: lecithin, polysorbate 80 and mono- and diglycerides.

Many gums are fermentable fiber

Most gums aren't digested in the small intestine. Like other soluble fibers, they reach the colon, where bacteria can ferment them. That can be helpful, and it can also mean gas.

Xanthan gum. In an older study, 18 healthy volunteers took 15 g of xanthan gum a day for 10 days. It worked as a highly efficient laxative, significantly increasing stool output, how often people went and flatulence. Their gut bacteria also adapted: before the study, stool samples from 12 of the 18 people could break the gum down in the lab, and afterward 16 of 18 could (Daly et al., 1993). Foods typically use xanthan gum as a thickener in much smaller amounts than that study dose.

Gum arabic. When healthy volunteers took 5, 10, 20 or 40 g of gum arabic a day for up to 4 weeks, levels of bifidobacteria and lactobacilli in their stool rose, with the best effect around 10 g a day. The researchers didn't find significant drawbacks, and at that dose the rise in these bacteria was at least as large as with 10 g of inulin (Calame et al., 2008).

Guar gum. A processed, shorter-chain form called partially hydrolyzed guar gum is sold as a fiber supplement and has been studied in people with IBS. We covered how it compares with inulin here.

The emulsifier question: cellulose gum

Animal and lab studies suggested that some emulsifiers can disturb gut bacteria and intestinal health. A carefully controlled human study tested one of them. Healthy adults ate only emulsifier-free meals for 11 days. Nine ate the diet as is, and seven had the same diet with 15 g a day of CMC added (Chassaing et al., 2022).

Compared with the control group, the CMC group had modestly more abdominal discomfort after meals, less diverse gut bacteria and lower levels of short-chain fatty acids in their stool. In two people on CMC, bacteria had moved closer to the normally bacteria-free inner mucus layer, a feature seen in gut inflammation.

It's a small, short study with a high dose, so it can't show what years of normal eating do. But it's a reason researchers are taking the question seriously.

Carrageenan and ulcerative colitis

In a small randomized trial, people with ulcerative colitis in remission followed a carrageenan-free diet and took either placebo capsules or capsules with carrageenan. Of the 12 patients who completed the questionnaires, 3 who received carrageenan relapsed, and none who received placebo did (Bhattacharyya et al., 2017). The trial was tiny and only included people with ulcerative colitis, so it doesn't tell us about everyone else.

So should you avoid them?

The honest answer is that the human evidence is still thin. The studies are small, short and often use doses higher than everyday eating. That isn't proof of harm, and it isn't proof of safety either. A practical middle path:

• Notice stacking. A day of plant milk, yogurt, a bar and a shake can add several gums and added fibers together.
• Test, don't guess. If you bloat easily, swap one gum-heavy product for a simpler version for two weeks and track your symptoms.
• Don't give up whole foods. Cutting additives isn't a reason to cut vegetables, beans or whole grains without a plan.
• If you have IBD, ask your gastroenterology team whether limiting emulsifiers or carrageenan makes sense for you.

When to see a doctor

Diarrhea that lasts, blood in your stool, weight loss you can't explain or symptoms that wake you at night need a medical check, especially if you have a family history of inflammatory bowel disease, celiac disease or colon cancer.

Sources

1. Daly J, Tomlin J, Read NW. The effect of feeding xanthan gum on colonic function in man: correlation with in vitro determinants of bacterial breakdown. Br J Nutr. 1993;69(3):897-902. PMID 8329363
2. Calame W, Weseler AR, Viebke C, Flynn C, Siemensma AD. Gum arabic establishes prebiotic functionality in healthy human volunteers in a dose-dependent manner. Br J Nutr. 2008;100(6):1269-75. PMID 18466655
3. Chassaing B, Compher C, Bonhomme B, et al. Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome. Gastroenterology. 2022;162(3):743-756. PMID 34774538
4. Bhattacharyya S, Shumard T, Xie H, et al. A randomized trial of the effects of the no-carrageenan diet on ulcerative colitis disease activity. Nutr Healthy Aging. 2017;4(2):181-192. PMID 28447072

This article is for general information and isn't medical advice. If you have IBD, IBS or another digestive condition, talk to your healthcare provider or a registered dietitian before making major changes to your diet.