A gluten-free diet is one that excludes most grains, and it is recommended for people who have celiac disease or gluten sensitivity. For other people, however, going gluten-free can be unhealthy. The benefits and risks of a gluten-free diet should be carefully weighed, especially if the person starting the new diet doesn’t really need to restrict gluten intake.
What is gluten?
Gluten is a protein found in some grains, such as wheat, rye and barley. Gluten makes bread products chewy and gives them an elastic quality, so it is important to the making of baked goods.
Gluten is the only protein found in food that is completely indigestible. Its indestructible molecules can slip through the intestinal lining and cause inflammation in the intestines of people with celiac disease, according to the Mayo Clinic.
In healthy people, the inside of the small intestine is lined with finger-like projections called villi that help the body absorb nutrients. In people with celiac disease, gluten irritates the lining of the small intestine and also causes the immune system to attack the villi. Over time, the villi can be damaged or destroyed.
This often means that the body can no longer absorb enough nutrients from food. Nutrients pass through the digestive tract and are excreted with the body's waste, and the person can suffer malnutrition, according to WebMD. According to the U.S. Department of Health and Human Services, celiac disease affects about one in 141 people in the United States.
Gluten-free diet benefits
Besides celiac disease, there are other medical conditions that greatly benefit from a gluten-free diet. “Gluten intolerance ranges from gluten sensitivity (non-celiac gluten intolerance) to celiac disease,” said registered dietitian nutritionist Jessica Fishman Levinson. "Non-celiac gluten intolerance could be an allergy to gluten or to other ingredients in food besides gluten, or it could even be a placebo effect, which some studies have actually showed."
Eating gluten-free can also help those with a chronic gastrointestinal disorder called irritable bowel syndrome (IBS). A low FODMAP diet — which stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols — is often helpful for people with IBS. Gluten-free is part of this diet.
“These are starches and sugars naturally found in certain foods or added to foods,” said registered dietitian Lori Chong. "The gluten grains (wheat, rye and barley) are high FODMAP foods. They contain oligosaccharides that can be easily fermented by intestinal bacteria. This can cause bloating, cramping and/or diarrhea." IBS affects 7 to 20 percent of the adult population in the United States, according to a 2013 paper published in the journal Gastroenterology & Hepatology.
“A gluten-free diet is essential for people with celiac disease and non-celiac gluten sensitivity. Diet is the only treatment for these conditions,” Chong told Live Science.
Autism and gluten
Although some have suggested that a gluten-free diet may help alleviate the signs of autism in children, there have been conflicting findings. A double-blind study published in the April 2006 issue of the Journal of Autism and Developmental Disorders found that a gluten-free and casein-free diet did not help those with autism. Another study by the Harvard Medical School found similar results.
Despite these findings, many parents and hospitals, such as the Children's Hospitals and Clinics of Minnesota reports that a gluten-free diet does seem to help with improvement in behavior, social skills, and learning in children with autism.
Many people on gluten-free diets don’t have a medically needed dietary restriction and eat gluten-free as a fad diet.
“Gluten free foods have been rising in popularity and many people seem to think, ‘It's gluten free so it must be healthy.’ This is not necessarily the case,” said Chong.
In an "Expert Voices" column for Live Science, Katherine Tallmadge, a registered dietitian, wrote that according to a July 2015 Gallup Poll, 21 percent of Americans are making an active attempt to eat gluten-free. That percentage dwarfs the 1 percent of the U.S. population diagnosed with celiac disease. [Related: The Dangers of Going Gluten-Free]
The biggest risk of going gluten-free is missing out on a healthy, well-balanced diet. Chong pointed out that there are many gluten-free products on grocery store shelves that are just as unhealthy as their wheat-based counterparts. Examples includes bread and bread products like waffles, pancakes, crackers, snack chips and pretzels made with white rice flour, tapioca flour and/or potato starch, cakes and cookies.
Tallmadge wrote, "Gluten-free foods, especially refined foods processed to make them gluten-free (Many made with potato starch or rice starch), cheat the consumer out of the many health benefits of whole grains … and can be seriously lacking critical nutrients such as fiber, iron, zinc, folate, niacin, thiamine, riboflavin, calcium, vitamin B12 and phosphorus."
Levinson would agree. “Personally I do not believe there is a benefit to eating gluten-free if you don't have a gluten intolerance," she told Live Science. "Many people think gluten-free food is healthier — lower in calories, lower in fat, etc. — but that is not always the case," she said.
People who only eat foods that are inherently gluten-free, like fruits, vegetables, gluten-free whole grains, lean protein, healthy fats, then gluten-free can be a healthy diet. "But if gluten-containing products are replaced with highly processed gluten-free foods like pastries, energy bars, etc., you will not lose weight and you may in fact gain weight as many GF foods are higher in calories than their gluten-containing replacements,” added Levinson.
Addressing the claims by people without celiac disease that following a gluten-free diet makes them feel better, Tallmadge wrote, "… the feeling of wellness that many attribute to the removal of gluten from their diets is more likely due to the absence of the refined carb- and sugar-laden snacks and desserts that happen to contain the protein. But why not simply cut out those refined foods and keep the healthy gluten-containing foods?
What to eat; what not to eat
Some grains are naturally gluten-free, such as brown rice, buckwheat, quinoa, wild rice, amaranth, sorghum, millet, corn (polenta) and teff. “Oats are naturally gluten-free, but are often contaminated with wheat in the field or at the mill. So buying certified gluten-free oats is necessary for someone requiring a gluten-free diet,” said Chong.
The Mayo Clinic lists several foods that are naturally gluten-free:
- beans, seeds and nuts in their natural, unprocessed form
- fresh eggs
- fresh meat, poultry and fish (not marinated, breaded or batter-coated)
- fruits and vegetables
- most dairy products
Mayo also recommends these grains and starches:
- corn and cornmeal
- gluten-free flours (rice, soy, corn, potato, bean)
- hominy (corn)
Mayo advises avoiding all food and drink that contains barley, rye, triticale (a cross between wheat and rye) and wheat. Wheat flour goes by many names, so it is a challenge to avoid them as well, such as durum flour, farina, graham flour, kamut, semolina and spelt.
These foods should be avoided unless they are labeled as gluten-free or made with gluten-free grain, such as corn, rice or soy:
- cakes and pies
- communion wafers
- cookies and crackers
- French fries
- imitation meat or seafood
- processed luncheon meats
- salad dressings
- sauces, including soy sauce
- seasoned rice mixes
- seasoned snack foods, such as potato and tortilla chips
- self-basting poultry
- soups and soup bases
- vegetables in sauce
Some other tips from the Mayo Clinic:
- Watch for cross-contamination. Cross-contamination can happen during production, so labels should be read carefully for "may contain" statements.
- Be careful about eating out at restaurants. Ask the staff about gluten-free choices on the menu, and try to find out how it is prepared to avoid cross-contamination.