Research studies of the human microbiome, often referred to as our 'ancient allies,' are revolutionizing understanding of the health benefits of a high-fiber diet. In this article, we discuss how fiber improves overall health, thanks to the symbiotic relationship we share with our gut flora.

Plant fibers and the microbiome

Plant fibers constitute a major component of all plant cell walls. Not only have these been instrumental in the development of various human necessities such as clothing, shelter, and food, but they’ve also played a pivotal role in the dietary evolution of our species. The significance of a fiber-rich diet is now widely acknowledged by leading global health organizations for playing a crucial role in preventing and managing several chronic health conditions, including obesity, diabetes, cardiovascular diseases, and inflammatory disorders. Dietary fibers are deemed essential for nurturing a healthy gut microbiome, with an array of food items like fruits, vegetables, beans, whole grains, and unsalted nuts recommended to enhance fiber intake.

As research begins to uncover the crucial role our microbiota has on health and disease, it also develops a better understanding of the benefits of high fiber diets, and the consequences of not maintaining a nutritious, balanced diet with recommended levels of fiber intake.

The Modern vs. Historical Diet

Modern Western diets, typically high in fat and low in fiber, starkly contrast with those of traditional societies that are instead dense with both soluble and insoluble fiber which has been shown to significantly affect gut microbiome composition. Many important studies of the last decade or more, such as this one comparing gut flora of European children with those from a rural African village, highlight how a diet rich in plant fibers nurtures microbiomes capable of efficiently breaking down these fibers, thereby supporting overall health. Researchers hypothesized that the relative reduction in microbiota richness they observed in European children "could indicate how the consumption of sugar, animal fat, and calorie-dense foods in industrialized countries is rapidly limiting the adaptive potential of the microbiota."

Health benefits of a high-fiber diet and a healthy microbiome

A diverse and balanced microbiome is akin to a protective shield against pathogens. However, a diet deficient in fibers can compromise this protective barrier, leading to increased vulnerability to infections and chronic inflammation that can lead to disease. Maintaining healthy gut flora through a high-fiber diet is thus not only a matter of nutritional adequacy but also a critical factor in disease prevention.

Some critical links between fiber-rich diets and maintenance of a diverse, balanced microbiota were illuminated in a recent study by Desai and colleagues. Typically, food sources of a healthy microbiota are energy-rich plant fibers that pass through the stomach to reach the small intestine undigested. However, when dietary fiber is low or absent, gut bacteria must switch to an alternative energy source - the glycoprotein-rich mucus layer of the gut wall. Because this layer functions as the gut's first line of defense against invasive pathogens, this can be a big problem as its diminishment  increases the host’s susceptibility to infection.

Diets high in fiber have also been shown to be protective against the development of chronic diseases. In one large meta-analysis published in the Lancet, researchers found that high-fiber diets were associated with 15-30% fewer  cardiovascular-related deaths and diagnoses of coronary heart disease, stroke, type 2 diabetes, and colorectal cancer relative  to low-fiber diet groups. These findings suggest that individual intake of dietary fiber should be no less than 25–29 grams per day for adults and additional benefits likely to accrue with further increases. 

Optimize your fiber intake for gut health

So, what can you do to support and enhance microbiome health?

First, evidence is mounting that early-life events can have a long-term impact on microbiome-related health. Mothers pass their own microbiota to their children during natural childbirth and breastfeeding. These events represent opportunities for mothers to “inoculate” with beneficial bacteria while their children are still developing the complex “organ” that is the microbiome. For this reason, women should avoid unnecessary perinatal antibiotics.

For adults, adopting a lifestyle that includes a balanced diet rich in fiber and low in refined foods is key. Simple dietary swaps, like choosing whole grains over refined ones and opting for fruits and vegetables instead of sugary snacks, can significantly improve one's microbiome health. Aiming for at least 25–30 grams of fiber daily is widely recommended to enhance gut health and, by extension, overall well-being.

Are you eating enough fiber? The reality is that most people don’t. Learn how much fiber is in each serving of various foods from the USDA or consider using a food logging app to get a sense of the amount of fiber you consume in a typical day. 

Gut health support from your Fountain Life team

Our healthcare team at Fountain Life, including dedicated health coaches, is committed to providing personalized support for our members’ journeys toward a healthier microbiome and diet. We can help identify individual needs and develop tailored strategies that encompass dietary adjustments, lifestyle modifications, and targeted supplementation. Our comprehensive approach ensures that each member receives the guidance necessary to nurture gut health and unlock the full potential of their microbiome with our expert support every step of the way. 

References

• Rook G, Bäckhed F, Levin BR, McFall-Ngai MJ, McLean AR. Evolution, human-microbe interactions, and life history plasticity. Lancet. 2017 Jul 29;390(10093):521-530.
• De Filippo C, Cavalieri D, Di Paola M, Ramazzotti M, Poullet JB, Massart S, Collini S, Pieraccini G, Lionetti P. Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14691-6. 
• Desai MS, Seekatz AM, Koropatkin NM, Kamada N, Hickey CA, Wolter M, Pudlo NA, Kitamoto S, Terrapon N, Muller A, Young VB, Henrissat B, Wilmes P, Stappenbeck TS, Núñez G, Martens EC. A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell. 2016 Nov 17;167(5):1339-1353.e21. 
• McKeown NM, Fahey GC Jr, Slavin J, van der Kamp JW. Fibre intake for optimal health: how can healthcare professionals support people to reach dietary recommendations? BMJ. 2022 Jul 20;378:e054370. 
• Hou K, Wu ZX, Chen XY, Wang JQ, Zhang D, Xiao C, Zhu D, Koya JB, Wei L, Li J, Chen ZS. Microbiota in health and diseases. Signal Transduct Target Ther. 2022 Apr 23;7(1):135. 
• Mueller, Noel T. et al.The infant microbiome development: mom matters. Trends in Molecular Medicine, Volume 21, Issue 2, 109 - 117

Writer Bio

Jordan Pennells, PhD, is a Postdoctoral Research Fellow focusing on the development of predictive models to evaluate the quality of food and feed products processed through extrusion technology. 

Reviewer Bio

Tom Callis, PhD. Principal Scientist at Fountain Life. Dr. Callis is a geneticist and science communicator specializing in clinical genetics and precision medicine, with authorship of more than 20 peer-reviewed publications. At Fountain Life, Dr. Callis helps guide the development of preventative and digital healthcare products to improve healthspan and longevity.

DeAunne Denmark, MD, PhD is the Vice President of Translational Medicine at Fountain Life. Dr. Denmark is a physician-scientist specializing in molecular, laboratory, genetic, and integrative precision medicine for over 15 years. At Fountain Life, Dr. Denmark helps lead clinical research and other innovative diagnostic and therapeutic programs to advance personalized longevity and healthspan-based care.