This is a short one. The science speaks for itself.
Gluten is a protein found in wheat that gives bread dough its resilience. Without gluten, bread would be crumbly and would fail to rise. Protein levels in wheat vary from around 10% up to the high teens, with so-called “heritage” varieties, the oldest types, having some of the highest levels in general.
There are certain people, slightly less than 1% of the population, who have a specific allergic reaction to gluten called celiac disease. In celiac sufferers gluten causes inflammation of the cilia, the tiny hairlike projections in the intestines, which prevents them from absorbing nutrients. Celiac sufferers experience severe gastrointestinal symptoms and chronic malnutrition unless they eliminate all gluten containing foods from their diets.
Early in 2011 a researcher published a study establishing the concept of non-celiac gluten sensitivity, or NCGS. It was a set of less-severe gastrointestinal (and other) symptoms associated with the consumption of gluten. A cardiologist published a popular book (filled with errors of fact) on the subject later in 2011 and the idea took off.
Now there is a 10.5 billion dollar industry in the United States that fills entire sections of supermarkets with gluten free food. Any food item in the store that just happens to be gluten free is so labeled. Restaurants now carry gluten free options.
Jessica R. Biesiekierski, the researcher who performed that 2011 study on non-celiac gluten sensitivity, published a new study in 2013 with more participants and a more rigorous protocol. The results were a reversal of the previous study. Gluten did not cause symptoms in the individuals studied, and various biomarkers (signs of inflammatory response) had no relationship to gluten consumption.
Take a cue from the Japanese. They import 3.5 million metric tons of our wheat every year and consume wheat at a higher rate per capita than we do. They are less obese, healthier, and live longer. So be happy; have a bagel or some whole wheat toast. Maybe a plate of linguine arrabbiata. And stop worrying about gluten.