For six years the interdisciplinary Center for Gut, Grain and Greens, 3G, has examined the effects of either an increased intake of whole grains or a reduced intake of gluten-containing foods. The researchers studied the impact on human health and intestinal bacteria.
Central to the 3G collaboration are two comprehensive human studies looking at the effect of eating a diet that is rich in whole grains or low in gluten-containing foods.
The first study shows that when people replace refined grain products with whole grain varieties, the body's level of inflammation decreases. This lowers the risk of developing cardiovascular disease and type 2 diabetes. Rye bread in particular has a positive effect on the level of inflammation, the researchers revealed.
In contrast, a diet in which refined grain products are replaced with low in gluten food does not provide a detectable change in the body's content of inflammatory markers.
"As such, our studies help to strengthen the scientific evidence behind the dietary advice about choosing whole grain products for your health when you eat bread, pasta and other cereal-based foods," noted 3G Center project manager Tine Rask Licht, who is a professor at National Food Institute, Technical University of Denmark.
According to the studies, both types of dietary changes result in a small weight loss. The greatest weight loss was recorded in the whole grain study.
Gluten free changes gut bacteria
Study participants who switched to a whole grain diet did not exhibit a “significant” change in the composition of their gut bacteria. However, the low gluten diet resulted in a “drastic” change in the intestinal microbial population. The bifidobacteria bacteria – associated with a healthy gut - disappeared when the diet was low in gluten, researchers found.
The cause of this was not the absence of gluten protein but rather the absence of certain types of carbohydrates found in wheat, barley and rye. These types of carbohydrates are known to promote bifidobacteria.
"It's an interesting observation, as we usually associate the presence of bifidobacteria with a healthy gut," Rask Licht says. However, she is cautious about drawing a conclusion from the absence of these bacteria.
Feeling less bloated on a low gluten diet
Several participants reported feeling “less bloated” when they ate the low gluten diet compared with the control diet, which was rich in whole grain products.
The researchers suggested this is most likely because the change in the bacterial composition of the gut resulted in less gas developing in the gut.
"If you suffer from a bloated stomach - which, of course, can be really uncomfortable - and you therefore want to cut back on grain-containing products in order to feel less bloated, I would urge you to drop the white, refined bread types. Because if you also give up on rye and wholemeal breads, you will lose out on the health benefits, which our studies have shown are associated with consuming whole grains,” Rask Licht suggested.
‘This large investment worth every cent’
The multidisciplinary large-scale study was backed by significant investment from the Danish government and the project's partners. In total, the 3G Center has received DKK35 million (€4.7m) from the Danish Council for Strategic Research/Innovation Fund Denmark. In addition, the project partners have contributed DKK20 million (€2.7m) in co-financing.
"An interdisciplinary cooperation that requires so many different disciplines, as has been the case in the 3G Center, costs a lot of money, presents many challenges and takes a long time. However, it is a necessary approach to solve such a major societal challenge as the prevention of lifestyle diseases. In my view, this large investment is worth every cent if our research can help reduce the large human and financial costs of type 2 diabetes and cardiovascular diseases,” Rask Licht stressed.
Diabetes costs Danish society about DKK87 million (€11.6m) a day according to a study from the Danish Diabetes Association and the University of Southern Denmark. Cardiovascular disease is the cause of one in four deaths in Denmark, according to the Danish Heart Foundation.