Gluten-free diets are everywhere. Celebrities tweet about their new diet, grocery stores are filled with products labeled “No Gluten!” and restaurants often offer special menus or items that don’t have any gluten in them. So, what exactly is gluten? Is it harmful to your health? Should you consider going gluten-free?
What is Gluten?
Gluten is a protein composite found in wheat, rye and barley products. It helps dough to rise, giving many foods a chewy texture. Most breads, pastas, flour mixes, cereals and other baked goods are high in gluten. Bread flours are usually high in gluten while pastry flours have a lower content. Many dairy products are free of gluten, but those with malt flavorings (like processed cheeses, chocolate milk and hot chocolate) contain a lot of gluten. Gluten can be found in many foods that don’t seem obvious, such as salad dressings and sauces, some soups, lunch meats, fruit jams with syrups, and potato chips and French fries with additives. Many beers are high in gluten as well. Vegans and vegetarians who enjoy imitation meat might be surprised to find that gluten is often the basis for the products. Gluten can also be found in some non-food items such as lip balms, medicines, and vitamins.
If you’re not intentionally avoiding gluten, it may be a big part of your diet. You might even wonder, what doesn’t contain gluten? Here are a few foods that don’t contain any gluten: milk, fruits and vegetables, 100% fruit or vegetable juice, butter, eggs, lentils, peanuts, seeds, tree nuts, non-gluten-containing grains such as corn and brown rice, fresh fish, fresh shellfish, quinoa, and honey. Many stores sell gluten-free pasta, pretzels, and baked goods that are made from some of these ingredients.
Celiac disease affects 1 in 133 Americans — more than 2 million people — and they should avoid gluten. However, the number of people diagnosed with celiac disease is much smaller, because the disease is often overlooked or misdiagnosed. The only sure way to diagnose celiac disease is through a blood test that detects special antibodies, and an upper endoscopy, which is a procedure that allows doctors to examine the upper part of the gastrointestinal tract. If the blood test comes back positive, the doctors sample a piece of tissue (called a biopsy) to see if there is damage to the small intestine.
When people with celiac disease eat foods containing gluten, their immune system reacts by damaging their villi, which are the tiny hair-like projections lining the small intestine that help us absorb nutrients. That is why people with celiac disease are at higher risk of being deficient in many different nutrients.
Celiac disease can develop at any point in life, so people can be diagnosed during infancy or adulthood. People who have a family member, especially an immediate family member, with celiac disease are at much higher risk of developing the disease. It is most common in Caucasians and people of European descent, and women are affected more often than men. People with celiac disease are more likely to have autoimmune disorders like rheumatoid arthritis and lupus, as well as other disorders such as Down syndrome, intestinal cancer, intestinal lymphoma, lactose intolerance, type I diabetes, and thyroid disease.
Symptoms vary widely, which is why the diagnosis is not always made right away. Many people experience gastrointestinal symptoms such as abdominal pain, gas, bloating, indigestion, constipation, diarrhea, a change in appetite, lactose intolerance, nausea and vomiting, bloody stools and unexplained weight loss.1 Other symptoms may develop over time: fatigue, depression, anxiety, muscle cramps, seizures, bruising easily, missed periods, hair loss, numbness in extremities and growth delay in children. Often, these additional symptoms are from the inability to properly absorb nutrients. In children, symptoms include delayed puberty, poor weight gain, slowed growth, irritable behavior and the common gastrointestinal symptoms.
Some people with celiac disease do not show any symptoms, but the villi in their intestines are still being damaged, and they still have trouble absorbing nutrients.
There is no cure for celiac disease, but a gluten-free diet can make symptoms go away and help the villi in the intestines to heal. Doctors often recommend vitamin and mineral supplements to help treat nutritional deficiencies.
Gluten Sensitivity for People who Don’t Have Celiac Disease
Gluten can have unpleasant effects even on people who do not have celiac disease. A growing number of people report having gastrointestinal symptoms similar to those of celiac disease that disappear when gluten is removed from their diets. However, this condition, referred to as “non-celiac gluten sensitivity,” does not damage the intestine like celiac disease does. Although the symptoms are real and there is a link between consuming gluten and these symptoms, no clear diagnosis exists for gluten sensitivity. Unlike celiac disease, there is no way to test for non-celiac gluten sensitivity. For this reason, it is difficult to provide an accurate estimate of the number of people who are sensitive to gluten. Several researchers from Italy and the United States estimate that “gluten-reactive patients” account for approximately 10% of the global population, but a more exact number is not available.
Autism and Gluten
Some scientists have suggested that a diet free of gluten and casein, which is a protein found in dairy products, can improve symptoms and behaviors in children with autism spectrum disorder, or ASD. The theory is that children with autism may have an allergy or high sensitivity to foods with gluten or casein. Other researchers, however, have not found a connection between gluten and autism.
Icaro Camargo Batista and colleagues at the University of Brasília in Brazil examined 147 patients with autism spectrum disorder (ASD) and 211 patients with celiac disease to see if there is a relationship between the two conditions. They found no evidence for a link between autism and celiac disease or gluten sensitivity.
On the other hand, a 2012 study by Christine Pennesi and Laura Cousino Klein of Pennsylvania State University showed that a gluten- and casein-free diet can improve ASD symptoms. The researchers created an online questionnaire which was filled out by 387 parents of children with autism. The questionnaire asked about the children’s GI symptoms, suspected food sensitivities and food allergies and whether the children followed a gluten- and casein-free diet. The results showed that children who ate foods without gluten AND casein had fewer digestive and allergy symptoms, which resulted in an improvement in ASD symptoms and behaviors. Giving up gluten or casein helped, but not as much as omitting both from the diet. The problem with this study, however, is that it’s based on reports by parents, many of whom put their children on this diet because they believed it would work. A better study would be a randomized controlled trial where some children would be assigned to eat a regular diet and others would be assigned to eat a gluten-free diet, although even then results would be biased if the parents know which diet the child has. There have been several randomized studies of gluten and ASD, but all were very small and therefore could not be conclusive., Larger sample sizes are needed because that would be more representative of children with ASD.
Is a Gluten-Free Diet Healthy If You Don’t Have Celiac Disease?
Clearly, gluten can be harmful to people with celiac disease and troublesome for people with non-celiac gluten sensitivity, and these people should avoid gluten. But, what about the rest of us? Gluten-free diets are becoming more popular with the general population, even people who have never had any problem with gluten.
There is some evidence suggesting that a gluten-free diet may improve symptoms of irritable bowel syndrome and other gastrointestinal problems. However, some people are hopping on the gluten-free bandwagon because it’s trendy or because they think it will help them lose weight. There is no evidence that a gluten-free diet is an effective weight loss tool. FDA dietitian and consumer safety officer Rhonda Kane went even further, saying “there are no nutritional advantages for a person not sensitive to gluten to be on a gluten-free diet.” Gluten-free does NOT mean low sugar, low fat or low sodium. In fact, food manufacturers often add more fat and sugar to gluten-free versions of food that naturally contain gluten in order to mimic the taste and texture of these foods. What a gluten-free diet can do is limit the number of foods you eat, including foods you tend to over-indulge in (bread, pasta, cookies, etc.). However, eliminating so many different foods from your diet can cause deficiencies in many essential nutrients. According to a 2011 article published in the Journal of the American Dietetic Association, a gluten-free diet “may actually result in a diet that is low in carbohydrates, iron, folate, niacin, zinc, and fiber.”
A common misconception is that gluten is mainly found in bread. In fact, gluten is in many foods so following a gluten-free diet can be very difficult., and costly, too. Manufactured gluten-free products are often more expensive than their gluten-containing counterparts. However, they are more common than ever: U.S. sales of gluten-free foods reached $1.2 billion in 2010, more than double that of 2005.
The Bottom Line
People with certain conditions, especially celiac disease, must avoid gluten for health reasons. However, for those trying to lose weight, a gluten-free diet is not a good idea. It is difficult to follow, expensive, can result in nutrient deficiencies, and the gluten-free processed foods might, in some cases be more unhealthy than their gluten-containing counterparts.
Celiac Disease. National Digestive Disease Information Clearinghouse. National Institutes of Health. January 2012. Available at: http://digestive.niddk.nih.gov/ddiseases/pubs/celiac/index.aspx.
Sapone A, Lammers KM, Casolaro V, Cammarota M, Giuliano MT, De Rosa M…Fassano A. Divergence of gut permability and mucosal immune gene expression in two gluten-associated conditions: Celiac disease and gluten sensitivity. BMC Medicine. 2011;9(23).
Batista IC, Gandolfi L, Nobrega YK, Almeida RC, Almeida LM, Campos Junior D, Pratesi R. Autism spectrum disorder and celiac disease: No evidence for a link. Arquivos de Neuro-psiquiatria. Jan 2012;70(1):28-33.
Pennesi CM, Klein LC. Effectiveness of the gluten-free, casein-free diet for children diagnosed with autism spectrum disorder: based on parental report. Nutritional Neuroscience. Mar 2012;15(2):85-91.
Elder JH, Shankar M, Shuster J, Theriaque D, Burns S, Sherrill L. The gluten-free, casein-free diet in autism: results of a preliminary double blind clinical trial. Journal of Autism and Developmental Disorders. Apr 2006;36(3):413-420.
Whiteley P, Haracopos D, Knivsberg AM, Reichelt KL, Parlar S, Jacobsen J, …Shattock P. The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutritional Neuroscience. Apr 2010;13(2):87-100.
A glimpse at “gluten-free” food labeling. Food and Drug Administration. January 2012. Available at: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm265212.htm.
Gluten-free remains one of the most dynamic health and wellness categories. Euromonitor International. February 2011. Available at: http://blog.euromonitor.com/2011/02/gluten-free-remains-one-of-the-most-dynamic-health-and-wellness-categories.html.