Going gluten-free may mean different things to different people but one thing does not change, how or where the ingredients are sourced. With the ever-growing litany of gluten-free options available and more people jumping on the bandwagon, some serious side effects are being unearthed.

Food that does not contain wheat, barley, or rye is available in nearly every major fast-food restaurant; in fact, you would be hard-pressed to find a restaurant that does not offer at least one gluten-free option on its menu. 2012 alone saw over 200 million restaurant visits include a gluten-free order.

The consumer research firm NPD Group reports that 30% of adults are interested in limiting or completely avoiding gluten in their diets and sales of gluten-free products in the United States (the world’s largest consumer) reached $2.79 billion in 2015. The gluten-free market is projected to be valued at $7.59 billion in 2020.

Yet, only 1 in 133 (1%) Americans suffers from celiac disease, the genetic autoimmune disease that damages the villi of the small intestine, blocking the absorption of food nutrients when gluten is digested. Gluten-sensitivity, which presents with similar symptoms but does not cause intestinal damage, is only six times more prevalent.

Whether a gluten-free diet is chosen for medical reasons or to lose weight and reduce inflammation (claims that have not been proven), the risks may outweigh the benefits. Researchers at the University of Illinois, the University of Michigan, and the Geisel School of Medicine at Dartmouth find that a gluten-free diet may increase the risk of heavy metal exposure which may damage the brain and cause cancer.

Compared to people who consumed gluten, arsenic levels in 73 gluten-free individuals ranging in age from 6 to 80 were twice as high and mercury levels were up to 70% greater. Rice flour, a popular addition to the spectrum of alternative flours, is known to bioaccumulate heavy metals from fertilizers, soil, and water may be the culprit.

Further, nutritional deficiencies may develop when a gluten-free diet is undertaken, as the fiber content of these products is often lower and key nutrients are missing such as folic acid (important for pregnant women) and iron. There is also the possibility that such a diet may decrease the level of healthy gut bacteria. To make matters worse, sugar and salt often take the place of the strong texture and flavor of gluten laden foods so many who attempt to use a gluten-free diet to lose weight end up becoming increasingly unhealthy.