“Microbiome”, Small Friends in Low Places!
Trillions of microscopic bugs (organisms) live in the human digestive tract, with the greatest concentration found in the large intestine, or colon. Until recently, not a lot of attention was given to these creatures because, 1) the technology wasn’t available to study them, and 2) come on, we’re talking about poop bugs; how important can they really be?
Improvements in molecular technologies have enabled an explosion of scientific research indicating that the bacteria living in the large intestine, the gut microbiota, play a critical role in human health and wellbeing, influencing our physiology, metabolism, nutrition and immune function. Furthermore, a disruption or damage to the gut microbiota, called “dysbiosis”, has been associated with various diseases including inflammatory bowel disease (ulcerative colitis, Crohn’s disease), diabetes, colorectal cancer and obesity. (1),(2),(3)
Key modulator of the composition of the gut microbiota
There are perhaps a 1000 different species of bacteria in our gut which can be divided into two main categories:
beneficial, health-promoting bacterial species and
pathogenic, disease-promoting bacterial species
A healthy gut microbiota is one in which there is a great diversity of beneficial bacteria, and they predominate over the pathogenic ones.
Although there is a genetic component to the gut microbiota, environmental and lifestyle factors are huge determinants of its composition, with the foods we eat being the major player. Research shows that what we eat influences which category of bacterial species predominate.
Dietary fiber is a key nutrient for fueling the beneficial bacterial species. They ferment fiber, especially soluble fibers, into three different short-chain fatty acids, which have health-promoting effects, including maintaining intestinal health, suppressing inflammation and carcinogenesis, promoting central nervous system and cardiovascular health.(4)
Dietary fiber is only found in plant foods, making it essential to eat fruits, vegetables, beans, whole grains, nuts and seeds in support of a healthy gut microbiota. The greater the diversity of fiber foods eaten, the greater the abundance and diversity of the beneficial bacterial species.
What about probiotics?
Probiotics are highly concentrated amounts of live, beneficial bacteria strains, often delivered in foods or supplements. There is evidence that probiotics can be helpful for numerous health conditions including irritable bowel syndrome, antibiotic-associated diarrhea, allergies, inflammatory bowel disease and female urogenital problems.(5) Supplements are not regulated in the US, so there is no guarantee that probiotic supplements actually contain the bacteria listed on the label and are safe and effective. Because the health benefits of probiotics are bacteria specific, you might want to consult your doctor or other healthcare professional before taking probiotic supplements.
You can’t fully optimize beneficial bacterial diversity by simply taking probiotics; similarly, you can’t optimize your fiber intake by getting all your fiber from fiber supplements. In other words, you can’t reverse the adverse effects of a low-fiber diet on the gut microbiota by simply taking probiotics and/or fiber supplements. The most comprehensive health benefits are derived from eating a diversity of fiber-rich plant foods.
Fiber-Fueled
Dr Will Bulsiewicz, internist and gastroenterologist, recently authored a book, Fiber-Fueled (6), which shares how to achieve a healthy gut microbiota by eating a high-fiber diet based on whole, unprocessed plant foods. Written for the lay audience, Dr ‘B,’ is passionate about helping people realize the powerful impact of the gut microbiota on their health. His engaging, enthusiastic style is driven by his own health journey and the results he sees in his many patients. For those of you who want to review the evidence-base, at the end of each chapter, supporting studies are referenced, with more than 430 study references in total. The book covers a full range of gut health topics, including probiotics, gluten and low-carb diets, and provides a 4 week plan of fiber-filled recipes, menus and shopping lists.
Recommendations
In order to optimize your gut microbiota and your health, eat an abundance of whole, unprocessed fiber foods, fruits, vegetables, beans, whole grains, nuts and seeds, at every meal, including probiotic-enriched foods and supplements when medically appropriate.
Need help adding fiber foods to your plate? Sign up for the free Full Plate Living Membership with self-paced courses, recipes, workshops and more.
View the Full Plate Living Healthy Gut Microbiome 101 Workshop
Article References
Valdes AM, Walter J, Segal E, Spector TD. Role of the gut microbiota in nutrition and health. BMJ. 2018;361:k2179. Published 2018 Jun 13. doi:10.1136/bmj.k2179
Guinane CM, Cotter PD. Role of the gut microbiota in health and chronic gastrointestinal disease: understanding a hidden metabolic organ. Therap Adv Gastroenterol. 2013;6(4):295‐308. doi:10.1177/1756283X13482996
Shen TD. Diet and Gut Microbiota in Health and Disease. Nestle Nutr Inst Workshop Ser. 2017;88:117‐126. doi:10.1159/000455220
Sivaprakasam S, Prasad PD, Singh N. Benefits of short-chain fatty acids and their receptors in inflammation and carcinogenesis. Pharmacol Ther. 2016;164:144‐151. doi:10.1016/j.pharmthera.2016.04.007
https://www.health.harvard.edu/vitamins-and-supplements/health-benefits-of-taking-probiotics
Bulsiewicz W. Fiber Fueled. New York, USA: Penguin Random House LLC; 2020.
