Xanthan Gum
In plain terms
A natural thickener made by fermenting sugar with a soil bacterium, used in both food and skincare. Gentle on skin and broadly safe to eat, with a couple of small caveats around large doses and infant feeding.
What the evidence shows
Xanthan gum is a polysaccharide produced by fermenting sugars with the bacterium Xanthomonas campestris, then drying the result into a powder that thickens and stabilizes. On skin it is gentle: the CIR panel found the microbial polysaccharide gums safe as used, and it is not a skin irritant or sensitizer, which is why it appears in products aimed at sensitive skin. Eaten, it is one of the better-studied additives; the EU re-evaluated it as E415 and found no safety concern for the general population and no need for an intake limit, and it has been FDA-approved in food since 1969. The caveats are minor and worth stating plainly. Large amounts eaten at once can cause gas, bloating, or loose stools, since it acts partly as soluble fiber. Allergy is rare and usually traces to the corn, wheat, soy, or dairy the sugar was fermented from rather than the gum. One narrow but real medical caution stands out: thickening agents based on xanthan gum should not be given to premature infants, after such products were tied to a serious bowel condition in that group, which is why regulators keep it out of foods for the youngest infants. There is also early research on how it shifts the adult gut microbiome, a finding still short of demonstrated harm. For ordinary use on skin or in food, it is a safe, well-tolerated ingredient.
On the label
Listed as xanthan gum or E415. Nothing to avoid for general use. If you bake low-carb with it, large amounts can upset digestion, and it is not an appropriate feed thickener for premature babies.