A low-gluten diet alters the human microbiome. However, this may relate to quality of dietary fiber in the food, not a reduction in gluten itself. New evidence comes from a Danish study in which healthy adults showed significant weight loss and experienced less bloating on a low-gluten diet compared to when they consumed a gluten-rich diet.
The study included 60 volunteers age 22 to 65 who were not diabetic and did not have celiac or other gastrointestinal diseases. They consumed one of two diets for eight weeks, then the other diet for another eight weeks after a washout period between. The two tests replaced all cereal foods with either a low-gluten or an enriched-gluten product of similar nutritional quality. Gluten consumption averaged 2 grams and 18 grams per day, respectively, compared with 12 grams on a normal diet.
DNA from stool samples showed the low-gluten diet consistently altered abundance of 14 bacterial species. This did not affect the health of participants over eight weeks, though long-term effects are unknown. Microbial function decreased metabolism and availability of carbs for the gut to absorb.
Other subtle changes occurred, such as availability of various micronutrients. Glucose and fat metabolism remained unchanged. However, participants lost on average 1.8 pounds during the low-gluten diet despite consuming the same amount of food energy. The cause is uncertain and requires further study.
Participants reported less bloating on the low-gluten diet. Measurements of breath hydrogen backed up these subjective experiences. Chemical analysis indicated the cause was an altered fermentation process.
These results in Danish Caucasian volunteers need further study to be generalized to a wider population.