Happy National Nutrition Month! Since 1973, the American Academy of Nutrition and Dietetics has invited all of us eaters to build healthful eating habits during the month of March. This year, the Maize and Blue Cupboard is focused on the power of nutrition through our daily choices.
If you’ve heard anything about nutrition, you’ve probably heard about fiber. Dietary fiber, fermentable fiber, insoluble fiber. There are many categories. With all the other factors we’re supposed to be experts on—like the gut microbiome and inflammation and chronically high cortisol—understanding what these terms mean feels overwhelming. Hopefully, this article will demystify what’s going on with fiber and explain some new research findings to help you make informed decisions!
We hear a lot about fiber, but what is it actually? According to University of Michigan Medical School professor, Tom Schimdt, fiber is any plant material that the gastrointestinal (G.I.) system can’t digest alone. Fiber is a type of carbohydrate, meaning it is a molecule made of glucose. We need help from bacteria and fungi that live in our gut (the microbiome) to break down the fiber we eat. This is how we gain energy from fiber! When the microbiome breaks down fiber, it breaks down the long, tightly-packed chains of glucose into small, simple sugars. This fermentation process turns these sugars into fatty acids that our cells can use for energy (Martens EC, et al.).
Now that we know what fiber is, why is it so important? Fiber has a plethora of positive impacts on human health. Eating fiber feeds the good bacteria in our gut, maintaining G.I. health. Specifically, the fatty acids produced from fiber digestion strengthens the cells lining the stomach, thus preventing what’s colloquially known as “leaky gut syndrome”. Increased intestinal permeability causes stomach contents and metabolites to leave the gut and enter the bloodstream. There’s even evidence to support that poor gut health can be linked to mental health, including depression and anxiety disorders (Taylor, Andrew M., et al.).
The latest research on fiber highlights even more positive health outcomes. High fiber diets allow the bloodstream to absorb more “good” products (short-chain fatty acids), letting nutrients travel to the brain, the heart, and the rest of the body. A 2021 study suggests that eating whole grains, legumes, fruits and vegetables may lead to increased mental clarity and cognition. Whether or not it does (the jury’s still out), but combined with the findings of another study by the same researchers, it’s clear that fiber has a meaningful effect on the mind (“A Specific Dietary Fibre Supplementation Improves Cognitive Performance—An Exploratory Randomised, PlaceboControlled, Crossover Study.”).
It’s easy to push off preventative health measures until later, but building small habits into your day-to-day is more effective than trying to do it all at once. Just last year, researchers found that people who ate high fiber diets over a lifetime had a 43–56% lower risk of incident dementia (Li, et al.).
Adding in more fiber-rich foods doesn’t have to be hard. The daily recommended amount is between 16-25 grams, but most Americans don’t eat even half as much as recommended. Easy ways to get fiber in include incorporating frozen veggies and combining fiber with other food groups for a complete meal. Pantry items might be beans, lentils, oats, brown rice, whole grain pasta, canned or frozen vegetables. Reaching for an apple or banana when you’re on the go is also a great way to increase your fiber. There’s no real right way when it comes to upping fiber intake. Even minor increases can yield big results. The best thing is to do what consistently works for you!
References
Berding, Kirsten, et al. “Going with the Grain: Fiber, Cognition, and the MicrobiotaGutBrain Axis.” Experimental Biology and Medicine, vol. 246, 2021, pp. 796–811.
Berding, Kirsten, et al. “A Specific Dietary Fibre Supplementation Improves Cognitive Performance—An Exploratory Randomised, PlaceboControlled, Crossover Study.” Psychopharmacology, vol. 238, 2021, pp. 149–163.
Bourassa, Megan W., et al. “Butyrate, Neuroepigenetics and the Gut Microbiome: Can a High Fiber Diet Improve Brain Health?” Neuroscience Letters, vol. 625, 2016, pp. 56–63.
Taylor, Andrew M., et al. “Associations among Diet, the Gastrointestinal Microbiota, and Negative Emotional States in Adults.” Nutritional Neuroscience, vol. 23, no. 12, 2020, pp. 983–992.
Li, X., et al. “The Associations of Dietary Fibre and FibreRich Foods with the Prevalence and Incidence of Neuropsychological Health Outcomes in Older Adults.” Proceedings of the Nutrition Society, vol. 84, no. OCE1, 2025, E148.
Martens EC, Lowe EC, Chiang H, Pudlo NA, Wu M, et al. (2011) Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts. doi:10.1371/journal.pbio.1001221