Houston, Texas, USA : When healthy people eat a low-gluten and fibre-rich diet compared with a high-gluten diet they experience less intestinal discomfort including less bloating which researchers at University of Copenhagen show are due to changes of the composition and function of gut bacteria.
The new study also shows a modest weight loss following low-gluten dieting. The researchers attribute the impact of diet on healthy adults more to change in composition of dietary fibres than gluten itself.
An increasing number of people choose a low-gluten diet, even though they are not allergic to the dietary substance. This trend has sparked public debate about whether or not low-gluten diets are recommendable for people without allergies. Now, researchers from University of Copenhagen among others have looked into just that.
In an intervention study of healthy Danish adults, reported today in Nature Communications, an international team of scientists shows that a low-gluten but fibre-rich diet changes the community of gut bacteria and decreases gastrointestinal discomfort such as bloating and is linked to a modest weight loss. The changes in intestinal comfort and body weight relate to changes in gut bacteria composition and function.
“We demonstrate that, in comparison with a high-gluten diet, a low-gluten, fibre-rich diet induces changes in the structure and function of the complex intestinal ecosystem of bacteria, reduces hydrogen exhalation, and leads to improvements in self-reported bloating. Moreover, we observed a modest weight loss, likely due to increased body combustion triggered by the altered gut bacterial functions,” explains the leading principal investigator of the trial, Professor Oluf Pedersen, Novo Nordisk Foundation Center for Basic Metabolic Research at University of Copenhagen.
Change in dietary fibre composition seems to be the cause
The researchers undertook a randomised, controlled, cross-over trial involving 60 middle-aged healthy Danish adults with two eight week interventions comparing a low-gluten diet (2 g gluten per day) and a high-gluten diet (18 g gluten per day), separated by a washout period of at least six weeks with habitual diet (12 g gluten per day).
The two diets were balanced in number of calories and nutrients including the same amount of dietary fibres. However, the composition of fibres differed markedly between the two diets.
Based on their observations of altered food fermentation patterns of the gut bacteria, the researchers conclude that the effects of low-gluten dieting in healthy people may not be primarily due to reduced intake of gluten itself but rather to a change in dietary fibre composition by reducing fibres from wheat and rye and replacing them with fibres from vegetables, brown rice, corn, oat and quinoa.
No basis for change of diet recommendation yet
A low-gluten diet has previously been proposed to diminish gastrointestinal symptoms in patients with inflammatory bowel diseases and irritable bowel syndrome, disorders which occur in up to 20 percent of the general Western population.
The present study suggests that even some healthy individuals may prefer a low-gluten diet to combat intestinal discomfort or excess body weight.
“More long-term studies are definitely needed before any public health advice can be given to the general population. Especially, because we find dietary fibres – not the absence of gluten alone – to be the primary cause of the changes in intestinal discomfort and body weight. By now we think that our study is a wake-up call to the food industry. Gluten-free may not necessarily be the healthy choice many people think it is. Most gluten-free food items available on the market today are massively deprived of dietary fibers and natural nutritional ingredients. Therefore, there is an obvious need for availability of fibre-enriched, nutritionally high-quality gluten-free food items which are fresh or minimally processed to consumers who prefer a low-gluten diet. Such initiatives may turn out to be key for alleviating gastro-intestinal discomfort and in addition to help facilitating weight control in the general population via modification of the gut microbiota”, concludes senior lead investigator, Professor Oluf Pedersen.
The study was sponsored by the governmental Danish Innovation Fund and was integrated in the Danish Center for Gut, Grain and Greens involving researchers from University of Copenhagen, The Technical University of Denmark, University of Southern Denmark and academic research teams in Belgium and China.
Citation: A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults” Nature Communications.
Video: When healthy people eat a low-gluten and fiber-rich diet compared with a high-gluten diet they experience less intestinal discomfort including less bloating, a new study shows. The researchers attribute the impact of diet on healthy adults more to change in composition of dietary fibers than gluten itself.
Video credit: University of Copenhagen, Faculty of Health and Medical Sciences
The market for gluten-free food, touted as a cure for all ills, has grown by double digits in the past five years. But are such health claims half-baked? Maya Jerath, MD, PhD, the director of the Allergy and Immunology Clinic at the University of North Carolina School of Medicine, gives the “dough-down” on the gluten-free diet. Maya Jerath was not involved in the present study.
If you love traditional bread sticks, cake or cookies, you may find the recent popularity of the gluten-free diet bewildering.
Some bakeries and Italian restaurants now offer gluten-free products. You can find gluten-free pastas and breads in the aisles of many grocery stores. In fact, U.S. retail sales in gluten-free food increased 74 percent over a five year period, according to the Nielsen Co.
That growth has been fueled in part by an increasing number of people who blame gluten, a protein found in wheat, for ailments such as weight gain, depression, indigestion, fatigue, flu-like symptoms and arthritis.
“Anecdotally, there are lots and lots of patients who say that they have a gluten sensitivity,” said Maya Jerath, MD, PhD, the director of the Allergy and Immunology Clinic at the University of North Carolina at Chapel Hill School of Medicine. But she said that while the condition is probably real for some patients, the medical community doesn’t understand it well and doesn’t have tests for it.
At the moment, the only medically recognized reason to adopt a gluten-free diet is a diagnosis of Celiac disease, Jerath said.
Celiac disease is an autoimmune disorder triggered by eating gluten or related proteins in rye and barley. In susceptible people, the proteins cause the body’s immune system to attack cells in the intestine called villi. The disease can disrupt nutrient absorption and lead to diarrhea, chronic abdominal pain, anemia, a rash and other symptoms. About one in 130 Americans has the disease, although many remain undiagnosed.
The good news, Jerath said, is that once Celiac patients adopt a gluten-free diet, their intestines return to normal and symptoms disappear.
Unfortunately, avoiding gluten can be a daunting task. In addition to baked goods, pastas, pizzas, breads and soup-thickeners, adherents must abstain from an array of processed foods and consumer items, including some beers, soy sauces, spices, salad dressings, communion wafers, lipstick and even Play-Doh.
Because the gluten-free diet is so challenging to follow, Jerath said you should be reasonably sure you have a gluten sensitivity or Celiac disease before you attempt it.
“The more restrictions you have to put on your diet, the harder your lifestyle becomes,” she said. “Why do something that’s hard if you don’t have to?”
If you suspect you have Celiac disease:
• The disease can cause a wide range of symptoms.
• Talk with your doctor about your symptoms. To receive a formal diagnosis, you will need to take a blood test. If the test is positive, a doctor will likely perform a biopsy to confirm the presence of damaged intestinal villi. If you are diagnosed with Celiac disease, you can lead a long and healthy life, but you will need to to adopt a gluten-free diet.
• If you suspect you have non-Celiac gluten sensitivity: Unfortunately, no test can show for sure that you have a gluten sensitivity. But you should try keeping a food and symptom diary, Jerath said. You’ll need to record everything you eat for a set period of time, such as two weeks. You should also note your symptoms. After the record-keeping period is over, look for patterns. If you have a gluten sensitivity, your symptoms should appear in the diary each time you ate gluten. But if you ate gluten and then felt well at any time during the study period, you likely don’t have a gluten sensitivity, Jerath said.
Gluten Free: Necessary for Some, Optional for Others
With the growing popularity of gluten-free products at your local grocery store, you may have wondered if you should avoid eating gluten. Sidestepping gluten can be a lifestyle choice for many. But for those with a condition known as celiac disease, it’s a medical necessity.
Gluten is a protein found in wheat, barley, rye, and sometimes oats—ingredients often used in breads, pastas, and desserts. Some people get gas, diarrhea, or bloating after eating gluten. These symptoms could be caused by intolerance to the protein or a wheat allergy, but celiac disease is different.
When a person with celiac disease eats or drinks anything with gluten, the body’s immune system attacks the inside of the small intestine. The damage from this attack keeps the body from absorbing needed nutrients. If left untreated, celiac disease can lead to malnutrition, depression, anxiety, anemia, or weakened bones. It can also delay children’s growth.
Celiac disease can be hard to spot, because its symptoms can be similar to other disorders. The condition affects about 1% of people worldwide; nearly 80% of them haven’t been diagnosed, says Dr. Alessio Fasano, a celiac disease specialist at Massachusetts General Hospital. “Celiac disease is a clinical chameleon. This creates tremendous confusion and challenging situations for both health care professionals and people who are trying to understand what’s wrong with them,” Fasano says.
Your doctor can use a blood test to look for signs of celiac disease. Before the test, continue eating foods with gluten. Otherwise, the results may be negative for celiac disease even if you have it. Eating a regular diet can also help your doctor determine if you have a form of gluten sensitivity that is not celiac disease. Gluten sensitivity is something you may grow out of over time, Fasano explains, whereas celiac disease is a lifelong condition.
If your tests and symptoms suggest celiac disease, your doctor may confirm the diagnosis by removing a small piece of your intestine to inspect it for damage.
Genetic tests may be used to detect the genes that turn on the body’s immune response to gluten. Such tests can help rule out celiac disease, but they can’t be used for diagnoses; many people who have the genes never develop celiac disease.
Fasano’s team is studying why some people with these genes don’t have symptoms. The NIH-funded researchers will follow infants who are at increased risk because a family member has celiac disease. The team hopes its findings will help doctors predict who will get celiac disease and learn how to prevent it.
People with one autoimmune disease are at increased risk for other autoimmune diseases. Because celiac disease and type 1 diabetes share risk genes, a large international study is following newborns at risk for both conditions to identify environmental factors that may trigger or protect from these diseases.
Going on a strict 100% gluten-free diet for life remains the only treatment for now. “We can’t take the genes out, so we remove the environmental trigger,” Fasano says.
Gluten is sometimes found in unexpected sources—such as medications, vitamins, or lip balms—so check ingredient lists carefully. The U.S. Food and Drug Administration has strict regulations for the use of “gluten-free” labels. Talking with a dietitian can also be helpful for learning about your food options.
If you suspect you may have celiac disease, talk with your doctor. Waiting too long for a diagnosis might lead to serious problems.