Seems like every day you hear about someone who’s gone gluten free, giving up all foods made with wheat, rye, or barley. You can expect that number to grow: New research published in the American Journal of Gastroenterologyindicates that about 1.8 million Americans have celiac disease (CD), the severe autoimmune reaction to gluten—but 1.4 million, or 83 percent, don’t know it.

Using information gathered from blood tests and surveys of 7,798 “nationally representative” people ages 6 and up, researchers found 35 people with CD; that extrapolates to 1 in 141 Americans. Remarkably, 29 of those were unaware of their condition.

“While we’ve made great strides in raising awareness and getting more people tested and diagnosed, this study shows we still have a ways to go,” says Rachel Begun, RD, blogger at The Gluten Free RD. “The longer people go undiagnosed and untreated, the greater their risk for long-term health complications.”