Gluten is composed of two proteins - gliadin and glutenin - that account for the intolerance to gluten that most individuals experience.

Let's start with gliadin. There are actually four types of gliadin - alpha, beta, gamma, and omega. The first three are related to digestive issues, while the fourth, omega-gliadin, is associated with skin rashes (urticaria) and asthma. It is the gliadin fraction of gluten that individuals with celiac disease react to. Glutenin is less likely to be a cause of disease or intolerance. It is glutenin that makes bread dough strong and elastic - think pizza dough being tossed at your favorite pizzeria.

Gluten is found mostly in wheat, rye, and barley. Gluten can be found in oats, but not because oats inherently contain gluten; rather, many oats are processed in facilities that also process gluten. In addition, brewer's yeast is typically contaminated with gluten because it's a by-product of beer brewing, which involves the gluten-containing grain barley.

Even if you don't have a serious reaction to gluten, you might find you feel better when you avoid it. If that is the case, then you aren't alone. Although less than 1 percent of the population has celiac disease, it is estimated that 6-8 percent of the U.S. population has gone gluten-free. A gluten-free diet can often help what ails you, even if gluten is not the culprit, because it eliminates wheat - a primary source of both refined carbs and unabsorbed, fermentable carbs (FODMAPS).

Although the way wheat is grown and processed has evolved over the years, the gluten content in wheat appears not to have changed much. So why does bread seem to be making people sicker? For one thing, gluten is often extracted from wheat and then added to many other products, including foods you would never imagine contained gluten. One study several years ago found gluten and other wheat by-products in almost one-third of processed foods in grocery stores.