A recent review article (J O’Grady et al. Aliment Phamacol Ther; 2019; 49: 506-15) highlights how fiber is important for health and its potential role in fostering a diverse microbiome. Some of the material has been covered before in a previous blog/presentation: It’s Alimentary!  “The Fiber Movement: Why Kids Need It and How to Get It” by Maria Oliva-Hemker .

In the introduction, the authors note that there had been a period of disappointment that fiber did not seem to help irritable bowel syndrome.  Though with expanding knowledge of the diet-, microbiome- host interactions, clinicians have started to appreciate the health impact of dietary fiber.

In subsequent sections, the authors detail the different types of fiber based on solubility, viscosity and fermentation.

Key actions of fiber:

• Anti-inflammatory effects
• Immune system modulation
• Regulation of cell proliferation and differentiation
• Richer microbiome diversity (may lower risk of C difficile)

The authors note that a low-fiber diet in germ-free mice can result in a reduced microbial diversity and interestingly, the “missing taxa is transmitted to subsequent generations” even if fiber is re-introduced.

Potential beneficial fiber effects beyond bulking up stools:

• Reduced adiposity
• Lower metabolic disease including lower cholesterol and better glucose metabolism
• Lower incidence of chronic inflammatory diseases
• “Potential for fiber to prevent… diverticular and neoplastic disorders”

Western Diet is Deficient in Fiber.

• Recommendations for fiber intake of 14 g per 1000 kcal consumed, which equates to approximately 25 g for females and 38 g for males (depending on energy intake).
• In underdeveloped countries and historically, intakes are more than 50 g (in Africa) and up to 100 g/day in ancestral humans
• Actual intake in U.S. is only 12-18 g/day.

The authors recommend efforts to gradually titrate increased fiber in the diet as abrupt changes may be poorly tolerated due to gas and bloating.

My take: This article explains that the connection between fiber intake and a number of health outcomes is likely due, at least in part, to its modulation of the microbiome. Thus, fiber is important for much more than a good poop.

Related blog posts:

•  It’s Alimentary! Part 1
• Why Fiber (Fruits and Veggies) Is Good For You
• Eat your veggies…if you do not want to get sick
• The Search for a Dietary Culprit for IBD
• Gut Microbiome, Crohn’s Disease and Effect of Diet
• Nutrition Week (Day 7) Connecting Epidemiology and Diet in Inflammatory Bowel Disease
• Dropping Weight by Adding Fiber in Diet | gutsandgrowth