Xanthan Gum: Why It's in Everything and Whether That's Fine
Quick Answer
Xanthan gum is a polysaccharide made by bacterial fermentation. It's FDA GRAS, widely studied, and safe for most people at typical food amounts. At very high doses it can cause digestive discomfort, and it's produced on corn, wheat, or soy substrates, something people with certain allergies should know about.
The Science
Xanthan gum shows up in salad dressing, ice cream, gluten-free bread, toothpaste, and industrial drilling fluid. That last one surprises people, but it illustrates something interesting about xanthan gum’s physical properties. The same features that make it useful in an oil well make it useful in your salad dressing.
Where Xanthan Gum Comes From
Xanthan gum is produced by fermenting simple sugars with the bacterium Xanthomonas campestris. This is the same bacteria that causes black rot in cruciferous vegetables like broccoli and cabbage. In a fermentation tank, however, it’s a controlled producer of a very useful polysaccharide.
The fermentation substrate is typically glucose or sucrose, often derived from corn starch, wheat, or soy. The bacteria secrete xanthan gum as a protective coating. After fermentation, the gum is precipitated out with isopropanol, dried, and milled into a fine powder.
The resulting powder is mostly the pure polysaccharide. Residual bacterial cells and substrate proteins are removed during processing. This matters for allergen questions, which we’ll cover shortly.
The Fascinating Physics of Xanthan Gum
Xanthan gum is what food scientists call pseudoplastic or shear-thinning. This means it thins under stress and thickens at rest. It’s the same principle behind non-Newtonian fluids, which behave differently depending on the force applied.
Here’s what that looks like in practice:
- A bottle of salad dressing with xanthan gum flows easily when you shake it or pour it (shear force applied), then settles into a thick, clingy texture when sitting on your salad (no shear force).
- Paint with xanthan gum spreads easily with a brush, then stays put and doesn’t drip.
- In oil drilling, xanthan gum keeps drilling fluid flowing under pump pressure but prevents it from flowing back when the pump stops.
This shear-thinning behavior is rare and valuable. Most thickeners add viscosity uniformly. Xanthan gum’s behavior is responsive to force in a way that’s extremely useful for texture engineering.
At the molecular level, this happens because xanthan gum forms a weak physical network at rest. The long polymer chains associate with each other. Under shear stress, the chains align and the network breaks apart. When stress is removed, the network reforms.
Deeper look: Xanthan gum's molecular structure
Xanthan gum has a cellulose-like backbone of glucose units linked in beta-1,4 bonds. Every other glucose unit carries a trisaccharide side chain made of mannose, glucuronic acid, and another mannose unit.
These charged side chains (glucuronic acid is acidic) repel each other, which keeps the molecule extended in solution rather than coiling up. The result is a molecule that takes up a lot of space relative to its mass, creating viscosity at concentrations as low as 0.1-0.5%.
The side chains also help xanthan gum perform consistently across a wide range of temperatures, pH levels, and salt concentrations. This stability is one reason manufacturers prefer it: it works predictably in acidic foods, salty foods, and across refrigerator-to-room-temperature storage.
What Xanthan Gum Does in Food
Xanthan gum does several things simultaneously, which is one reason it’s hard to replace:
Thickening. A tiny amount of xanthan gum significantly increases the viscosity of liquids. This is why it appears in salad dressings, sauces, and soups.
Stabilization. It keeps particles, oil droplets, and water from separating. This is why it appears in vinaigrettes, chocolate milk, and plant-based milks.
Texture in baking. In conventional baking, gluten provides the elastic network that traps gas bubbles and gives bread its chewy structure. Gluten-free flours don’t form this network. Xanthan gum partially replaces that function, giving gluten-free doughs enough structure to hold their shape and trap CO2 from yeast or baking powder.
Ice crystal control. In ice cream and frozen desserts, xanthan gum slows ice crystal growth during freeze-thaw cycles, keeping texture smooth even after temperature fluctuations.
Role in Gluten-Free Baking
For people with celiac disease or gluten sensitivity, xanthan gum is often the difference between gluten-free bread that holds together and crumbles to pieces. Most commercial gluten-free baked goods contain it for this reason.
The amounts used in baking are small. Typical gluten-free bread recipes call for 1 teaspoon of xanthan gum per 2 cups of flour, meaning you’re consuming a fraction of a gram per serving.
Xanthan gum doesn’t perfectly replicate gluten, though. It can’t match gluten’s viscoelastic stretch, which is why gluten-free bread has a different chew. But it’s the best widely available option for structure and gas retention. For more on what gluten actually does in dough, see our article on emulsification in cooking, which covers how different molecules create food structure.
What the Body Does With Xanthan Gum
Humans don’t produce enzymes that digest xanthan gum’s beta-glucoside bonds. So it reaches the large intestine largely intact. There, gut bacteria ferment it, producing short-chain fatty acids as byproducts, similar to other dietary fibers.
Some xanthan gum passes through undigested. The proportion that’s fermented versus excreted depends on an individual’s gut microbiome composition.
This fiber-like behavior is actually considered a minor benefit. Short-chain fatty acids like butyrate feed colonocytes (the cells lining the colon) and may have mild beneficial effects on gut health. The amounts from normal xanthan gum consumption are too small to drive significant effects, but they aren’t harmful.
At very high doses, roughly 15 grams per day and above, xanthan gum can cause loose stools and gas. These amounts were studied in clinical trials where xanthan gum was used as a therapeutic laxative (Vorwerk et al., 2003). The amounts in food are typically under 1 gram per day for even heavy consumers.
Allergen Considerations
Because xanthan gum is fermented on corn, wheat, or soy substrates, there’s a theoretical allergen concern. In practice, the purification process removes nearly all protein from the substrate. Multiple studies have tested xanthan gum for residual allergens and found levels below detection thresholds in most commercial products.
The FDA does not require xanthan gum to carry an allergen warning even when produced on wheat, based on this removal of allergenic proteins during processing.
That said, a very small number of reported cases describe reactions to xanthan gum in highly allergic individuals. If you have a severe corn, wheat, or soy allergy and are concerned, look for products using guar gum (derived from guar beans) or carrageenan as alternatives. Some brands also now specify the fermentation substrate on their packaging.
Comparing Common Thickeners
| Thickener | Source | Shear-Thinning | pH Stable | Freeze-Thaw Stable |
|---|---|---|---|---|
| Xanthan gum | Bacterial fermentation | Yes | Yes | Yes |
| Guar gum | Guar beans | Partial | Moderate | No |
| Carrageenan | Red seaweed | No | Yes | Moderate |
| Cornstarch | Corn | No | Moderate | No |
| Gelatin | Animal collagen | No | Yes | No |
Xanthan gum’s combination of stability, low required concentration, and shear-thinning behavior puts it in a category of its own for many applications.
Safety Status
The FDA granted xanthan gum GRAS status in 1969. It’s one of the better-studied food additives with decades of use across dozens of countries. JECFA (Joint FAO/WHO Expert Committee on Food Additives) has reviewed it multiple times and consistently found no safety concerns at food use levels.
The main safety consideration is the GI effects at high doses, and the substrate-allergen question for severely allergic individuals. Neither represents a concern at normal dietary exposure.
For most people, including people with celiac disease, IBS, and standard food allergies, xanthan gum in food is a non-issue.
What This Means for You
Xanthan gum is one of the better-studied food additives, and the evidence supports its safety. If you're eating gluten-free foods, you're consuming it regularly and that's fine. If you have corn, wheat, or soy allergies and want to be extra cautious, look for products using sunflower lecithin or guar gum as alternatives, though finished xanthan gum itself contains minimal residual allergens.
References
- EFSA ANS Panel. (2017). Re-evaluation of xanthan gum (E 415) as a food additive. EFSA Journal. 15(7):4909.
- Daly J, Tomlin J, Read NW. (1993). The effect of feeding xanthan gum on colonic function in man: correlation with in vitro determinants of bacterial breakdown. Br J Nutr. 69(3):897-902.
- FDA. Xanthan gum — GRAS status (21 CFR 172.695), granted 1969.
- JECFA. Xanthan gum — food additive evaluation. FAO/WHO.
- Petri D. (2014). Xanthan gum. In: Handbook of Hydrocolloids (Phillips GO, Williams PA, eds). Woodhead Publishing. Review of structure, production, and safety.
- Palaniraj A, Jayaraman V. (2011). Production, recovery and applications of xanthan gum by Xanthomonas campestris. J Food Eng. 106(1):1-12.