Horseradish is the root of a plant and therefore is gluten free but subject to cross-contamination during the processing that transforms it into an edible condiment, sauce, or dressing. We need to be concerned about the other ingredients involved. Very few commercially prepared horseradish sauces are labeled ‘gluten free’, but that could because the manufacturers assume that we assume that the sauces are ‘safe’.
FYI, horseradish is the root of a plant that is not part of the radish family and obviously has nothing to do with horses. Click here for more information.
People who live gluten free have three options: We can abstain from consuming horseradish, we can assume that there is no problem, or we can prepare our own horseradishes. Click here and/or here to read several recipes for horseradish sauce.