May 10, 2016
By Shilpa Ravella
For the trillions of bacteria that live inside your gut, what you eat is important, because it is what they eat. We are only beginning to understand that the make-up of gut bacteria can play an important role in preventing or treating disease and is influenced by many factors including food, medications and lifestyle. In two studies published last month in Science, researchers from the Netherlands and Belgium presented the largest microbiome research conducted to date. They evaluated 1,135 Dutch adults and 1,106 Belgians respectively and looked at how hundreds of factors affect the microbiome, with results that overlapped considerably.
Biodiversity boosts the productivity of an ecosystem, and the gut microbiome is no exception: variety is healthy. In the above studies, foods that promoted bacterial diversity included fruits, vegetables, tea, coffee, red wine, dark chocolate and yogurt. On the other hand, “Western” style dietary habits were associated with lower diversity including snacking, eating foods high in dairy fats and drinking sugar-sweetened soda. We know that fiber, found in whole plant foods like fruits, vegetables, legumes and whole grains, feeds intestinal bacteria and leads to the production of beneficial by-products like short-chain fatty acids, which nourish the gut barrier and help prevent inflammation. Polyphenols, naturally occurring antioxidant compounds that promote microbial diversity, are found in fruits and vegetables as well as tea, coffee, red wine and dark chocolate. Previous studies have shown that cacao powder, found in dark chocolate, is digested by gut bacteria to produce compounds that help the heart and reduce inflammation. Other gut-friendly foods contain probiotics, or beneficial bacteria present in yogurt and fermented foods used in traditional cultures around the world.
Medications had one of the biggest effects on gut microbiome diversity. Antibiotic use was associated with lower diversity, which is consistent with previous findings. Other drugs like proton-pump inhibitors, metformin, statins and laxatives also had a strong effect on the microbiome. Martin Blaser, director of the Human Microbiome Program at New York University and author of Missing Microbes: How the Overuse of Antibiotics is Fueling Our Modern Plagues, argues that children should be given probiotics along with antibiotics in order to restore a healthy microbiome.
Surprisingly, stool consistency was closely correlated with the make-up of the gut microbiome in the Belgian study. Stool consistency is not routinely considered in clinical studies and, along with medication use, can be a confounding factor, meaning that differences in the microbiomes of sick versus healthy people may be due to the consistency of their stool or medication use rather than a disease.
Microbiome science is still young. Changes in the microbiome have been linked to many different conditions, but it’s not always clear which came first. “Even though we’re the biggest study out there, we’re still scratching the surface,” said Jeron Raes, senior author of the Belgian study and a contributing author on the Dutch study. Raes checked his results against the Dutch data and confirmed over 90% of the findings, validation that is uncommon in microbiome studies. But most of the differences between individual microbiomes are still unexplained, and could be due to other lifestyle factors or genetics. We don’t yet have a blueprint for an “ideal” microbiome, which may not even exist. Adding to the confusion, single stool samples can’t capture the dynamic nature of the microbiome, which can shift from day to day.
In the meantime, as our understanding of how lifestyle factors shape the microbiome grows, we can try simple interventions to cultivate a diverse gut ecosystem. Use antibiotics only when you need them. Eat a good amount of fiber from whole foods and include fermented foods in your diet. When you want to indulge on occasion, reach for the red wine and dark chocolate. (from The Huffington Post)