What is this about?
Laura Pirkola of the Swedish University of Agricultural Sciences, Faculty of Natural Resources and Agricultural Sciences, Department of Molecular Sciences, presents findings from her dissertation. The results show that rye may have the potential to increase production of the short-chain fatty acid butyrate. Previous studies have shown that rye increases butyrate levels in humans. However, the effects on the gut-brain axis remain unclear.
What did the dissertation consist of, and why is it interesting?
The dissertation consisted of two studies. One compared different microbiota compositions through laboratory fermentation of whole-grain rye bread, whole-grain oat bread, and refined bread. The other was a dietary intervention in which healthy participants ate large amounts of either whole-grain rye bread or low-fiber bread for three weeks. The aim was to investigate how dietary fiber from different types of bread affects gut bacteria and the substances they produce. The study also examined whether whole-grain rye bread can influence the gut-brain connection. Interest in gut bacteria and the gut-brain axis has increased significantly in recent years. Despite this, knowledge about the health effects of whole grains remains limited. It is believed that whole grains can affect the brain directly or indirectly through gut bacteria’s communication with the brain.
What do the results show?
The researchers observed differences in the levels of short-chain fatty acids and other metabolites, as well as in how the microbiota from different donors utilized dietary fiber. This suggests that the composition of the microbiota may influence how nutrients from bread are utilized by the bacteria. The levels of a specific short-chain fatty acid, butyrate, differed between the two donors, particularly in samples containing rye. Researchers consider butyrate to be a key metabolite in the gut-brain axis. No significant changes in fecal microbiota composition or the gut-brain axis were observed in the three-week study with human subjects. A small increase in the abundance of two butyrate-producing microbes was observed in participants who consumed whole-grain rye.
The results suggest that certain grains or dietary fibers benefit individuals with a specific gut microbiota composition. The growing body of evidence regarding the role of gut microbiota composition and its effect on microbiota-derived metabolites presents an interesting angle for precision nutrition and product innovation. However, knowledge of the complex interactions between microbiota composition, dietary fiber utilization, and health effects remains very limited, and analysis of microbiota composition is not available to everyone. Therefore, it is beneficial to recommend increased intake of whole grains and the amount and variety of dietary fiber in the diet. Link to publication:
Gut-brain axis: the gut-brain axis is a two-way communication pathway between the gut and the brain in which the gut microbiota plays a central role. There is a large individual variation in the composition of the gut microbiota, which can affect its ability to produce different metabolites.
Short-chain fatty acids: When dietary fiber is fermented in the intestines, short-chain fatty acids are produced, which are important for our health because they nourish the intestines and can influence the immune system.