About 1% of the US population (3 million people) have Celiac disease, a disorder which makes it physically difficult to digest gluten and can lead to permanent damage to the digestive tract—this article is not for you. (The only way to know if you really do have the disease is via a blood test.)
This article is for the 18% of Americans who express a desire to eat gluten-free, and buy those foods without the protein, many of whom say they have 'gluten sensitivity.' Several studies (the newest being rather intensive, see below) have shown there is no verifiable, science-based evidence that it's gluten that causes the digestive distress many associate with gluten sensitivity.
Interestingly, the new information comes from the very same scientist who had originally found evidence of gluten sensitivity. Peter Gibson, professor of gastroenterology at Monash University and director of the GI Unit at the Alfred Hospital in Melbourne, Australia did a study in 2011 that found that gastrointestinal distress was caused by gluten in people without Celiac disease in a double-blind, randomized, placebo-controlled study. It is one of the studies routinely cited when people write or speak about the topic. But Gibson questioned his own results, and, as scientists do, looked more closely at the diverse set of issues people reported—he couldn't figure out what the causal mechanism was, and wondered if it was the gluten—or something else causing the variety of symptoms reported. So he did another study, this one incredibly rigorous, as far as nutrition studies go (which sometimes rely on self-reported information, and rarely isolate people, but rather depend on their honesty in reporting what they did—or didn't—eat).
According to the excellent breakdown/description of the study on Real Clear Science: "Subjects would be provided with every single meal for the duration of the trial. Any and all potential dietary triggers for gastrointestinal symptoms would be removed, including lactose (from milk products), certain preservatives like benzoates, propionate, sulfites, and nitrites, and fermentable, poorly absorbed short-chain carbohydrates, also known as FODMAPs. And last, but not least, nine days worth of urine and fecal matter would be collected. With this new study, Gibson wasn't messing around."
Subjects who had all reported Non-Celiac Gluten Sensitivity (NCGS)—37 of them—underwent the following (again, thanks to Real Clear Science for the explanation): "They were first fed a diet low in FODMAPs for two weeks, then were given one of three diets for a week with either 16 grams per day of added gluten (high-gluten), 2 grams of gluten and 14 grams of whey protein isolate (low-gluten), or 16 grams of whey protein isolate (placebo). Each subject shuffled through every single diet so that they could serve as their own controls, and none ever knew what specific diet he or she was eating. After the main experiment, a second was conducted to ensure that the whey protein placebo was suitable. In this one, 22 of the original subjects shuffled through three different diets -- 16 grams of added gluten, 16 grams of added whey protein isolate, or the baseline diet -- for three days each."
The results were that the subjects complained of gastrointestinal distress on all the diets; the placebo most of all. Gibson said, "In contrast to our first study… we could find absolutely no specific response to gluten."
This isn't to say that you might not have other food allergies or issues causing digestive distress or other health issues (I know, without a doubt, that consuming dairy caused my adult cystic acne, for example). As suggested by the research, it may be something else in your bread that is causing you to feel ill after you eat it. In addition to FODMAPs, old grain, preservatives, pesticides and other chemicals and unknown toxins could all be causing problems with digestion of bread or other foods that contain wheat. But if you don't have Celiac disease, it's probably not the gluten causing the problems—it's something else.
Takeaway? Processed foods containing preservatives and chemicals are probably the culprits for your digestion issues with bread—not gluten.
I have found that fresh-baked bread made from freshly-ground grains that haven't been stored for years (yes, that's common in America's food-industrial complex), not only tastes terrific, but never gives me any digestive issues.
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