Wheat, and more specifically, gluten, is the hot-button topic these days. Merrell attributes this sudden outburst of gluten toxicity to a change in how farmers grow wheat. "The modern wheat we eat today is in fact a highly hybridized foodstuff that contains dozens of carbohydrate and protein molecules that are new to the human body."
"Whole grain foods can be a healthy choice if you're among those who can tolerate them," Merrell says. "If you are sensitive to them, however, they can wreck your health." If you have celiac disease, the lining of your small intestine becomes damaged with exposure to gluten. Symptoms include upset stomach, chronic diarrhea, gassiness, bloating, fatigue, bone or joint pain, irritability, or headaches. It's also possible to show up negative to celiac disease yet still have a sensitivity to gluten.
Gluten is especially tricky because it can be found almost everywhere. Aside from general wheat products, watch out for bouillon cubes, licorice, canned soup, nondairy creamer, salad dressing, and yogurt premixed with fruit. These can all contain hidden traces of gluten.
More: The Hidden Sources of Gluten in Your Home