There has always been rumbling that spice makers secretly add flour to stretch out their spices and the outright incorrect information that silicon dioxide used to keep spices from clumping contains gluten.
There has been some concern that cross contamination, perhaps from seasoning mixes that sometimes do contain gluten, might be a problem. Many of the big spice companies say outright that their pure spices are gluten free. And we now have testing results to give us the facts about spices.
The Canadian Inspection Agency did a representative study of 268 domestic and imported spices consisting of a single spice. The samples were tested to 5 ppm of gluten. Although some of the samples tested did contain trace levels of gluten, most were well below the 20 ppm Food and Drug Administration standard for gluten-free labeling in the United States. Of those that tested positive, 97 percent would still be considered safe by proposed labeling standards, the Canadian agency concluded. One note, a sample of mace was found to contain 20,000 parts per million, a clear violation of gluten-free labeling standards and the product was quickly recalled.
Spices were recently also tested by a private firm in the US and were largely found to be gluten free, again with one outside exception of a spice that’s not commonly used in the United States.
The other thing to keep in mind is spices are generally not consumed unless they are part of another food. Since levels of gluten are typically measured as the number of ppms in a finished food, the total amount contributed by a spice would be even less, for example, than the 5 parts per million that might be found in a pure spice.