Vinegar is often a confusing food when it comes to gluten content. This goes back many years to a time when we assumed that because common white vinegar is distilled from a gluten containing grain then it must have gluten in it. At the time is was prudent to be safe rather than sorry.
Fortunately, later studies showed that the distillation process removed any gluten from the vinegar. This is true for alcohols as well. It has taken many years for this information to disseminate into the common knowledge about vinegar, but there is still room for confusion.
Other vinegars, such as red wine vinegar, apple cider vinegar, and balsamic vinegar also do not contain gluten. They are not derived from a gluten grain, therefore they never had gluten to begin with.
The primary exception to all of this is malt vinegar. “Malt” can almost always be assumed to mean “barley malt.” Barley is of course a gluten grain, and malt vinegar is generally not a distilled vinegar. Therefore there is gluten in malt vinegar. The other exception is when malt has been added into something after it has been distilled. This is sometimes the case with hard alcohols, but you have to check with the manufacturer.
So in most cases, if you have a gluten intolerance, you are safe with vinegar. Your typical vinegar in most processed foods is a distilled white vinegar, and that is usually indicated on the label. However, if you suspect that you have a problem with vinegar, there are other possible reasons for this. The main cause of reactions to vinegar is when people have a reaction to brewer’s yeast.
Brewer’s yeast is used in all vinegar and all alcohol products, though it too is lost in distillation. Proper testing will demonstrate whether or not one has a reaction to brewer’s yeast. This is not an unheard of reaction, but that is a discussion for another day.