People with celiac disease are sensitive to gluten, which is a protein found in wheat.

Less than 1% of the American population has even the mildest form of this disease, but at least 20% of SWPLs think they have this disease and demand gluten-free products.

Half Sigma is often wrong in my opinion, but I think he's hit this one pretty squarely. It's SWPL-nutrition-fashion.