Dietary Fiber: Easy Health Hack
Dietary fiber is the least “sexy” nutritional intervention. It struggles to compete for our attention with all the superfoods, popular diets, and fancy supplements hogging the limelight. And yet our body needs lots of fiber to stay healthy.
Getting adequate dietary fiber should be easy. Just eat whole foods! But most Americans eat a highly processed diet lacking adequate fiber.
One of my most frequent nutritional recommendations to clients is to increase their dietary fiber intake.
What is fiber anyway?
Fiber refers to the part of fruits, vegetables, grains, nuts, and beans that don’t break down when you eat them. While the nutrients in most food gets absorbed in the GI tract, dietary fiber makes its way all the way to the colon.
Fiber is also a carbohydrate. While most carbs also break down into sugar, dietary fiber helps bulk up your stools.
Fiber is critical to your health!
Health conditions associated with low-fiber diets
Constipation
Type II Diabetes
Obesity
High cholesterol
Certain cancers including colon and breast cancer
Diverticulitis
Gut microbiota overrun with “bad” bacteria
Constipation is not just an annoyance!
Low dietary fiber increases the risk of colon cancer, which is the second leading cause of cancer death. The gut microbiota needs fiber to make something called butyrate. Butyrate is the preferred energy source for colon cells. It also helps to suppress both inflammation and cancer (O’Keefe, 2016).
A high-fiber diet is thought to decrease the risk of breast cancer. Fiber reduces insulin and elevated insulin is associated with an increased risk of breast cancer.
Another possible explanation is that fiber improves elimination. When women suffer from constipation, circulating estrogen that the body is trying to eliminate gets re-absorbed in the colon. Reabsorption of estrogen increases the risk of hormone-dependent cancers. It should be noted that there are inconsistencies in the studies involving the link between fiber and breast cancer. Evidence supporting the cancer-prevention properties of a high-fiber diet is strongest for post-menopausal women (Farvid et al., 2020).
Regular bowel movements are a critical part of the body’s overall detoxification system.
Dietary fiber is also thought to reduce the nitrogen burden in kidney disease. The kidneys play a major role in detoxifying the body.
Dietary fiber also promotes the production of bile acids, a substance necessary for healthy overall metabolism. Bile acids are often low in cases of non-alcoholic fatty liver disease – an all-too-common medical problem these days!
And, of course, dietary fiber helps to feed all the good bacteria in our gut that keep us healthy and regular (Keiffer et al., 2016).
The painful condition of diverticulitis is also thought to be related to a low-fiber diet and the need to strain to pass a bowel movement (Wilkins et al., 2013).
For all these reasons and more, chronic constipation should never be ignored.
Soluble versus insoluble fiber
Soluble fiber absorbs water and dissolves into a gel. It is excellent for feeding your “good” gut bacteria. Examples include oats, barley, lentils, beans, and many fruits and vegetables. Soluble fiber plays a role in blocking the absorption of cholesterol in your gut. So the old Quaker Oats commercials are true after all –providing you avoid instant oatmeal or flavored oatmeal!
Insoluble fiber doesn’t dissolve in water. It is helpful for bulking up stools. Insoluble fiber reduces sugar spikes because it slows down the absorption of simple carbohydrates. Examples include nuts, bran, whole grains, brown rice, and many fruits and vegetables.
How much fiber do we need?
Experts seem to agree that we need at least 25-30 grams a day of dietary fiber. Most Americans only get 15 grams.
If you want to evaluate your diet for dietary fiber, there are many apps and websites that can help. I like www.cronometer.com. It’s free.
While a high fiber diet is best, supplemental fiber products can also be helpful.
Who should be cautious with high dietary fiber?
Anyone prepping for a colonoscopy
Anyone experiencing a flare-up of diverticulitis or inflammatory bowel disease should speak with their doctor
Acute diarrhea
Note: chronic diarrhea often requires added fiber for bulking up stools
Disclaimer
The included information is not meant to or should not be used to replace or substitute medical treatment, recommendations, or the advice of your physician or health care provider. The information contained within is strictly for educational purposes and is based on evidence-based nutrition. If you believe you have a medical problem or condition, please contact your physician or healthcare provider.
Sources:
Farvid, M. S., Spence, N. D., Holmes, M. D., & Barnett, J. B. (2020). Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Cancer, 126(13), 3061–3075. https://doi.org/10.1002/cncr.32816
Increasing fiber intake (2022) https://www.ucsfhealth.org/education/increasing-fiber-intake
Kieffer, D. A., Martin, R. J., & Adams, S. H. (2016). Impact of Dietary Fibers on Nutrient Management and Detoxification Organs: Gut, Liver, and Kidneys. Advances in nutrition (Bethesda, Md.), 7(6), 1111–1121. https://doi.org/10.3945/an.116.013219
O'Keefe S. J. (2016). Diet, microorganisms and their metabolites, and colon cancer. Nature reviews. Gastroenterology & hepatology, 13(12), 691–706. https://doi.org/10.1038/nrgastro.2016.165
Wilkins, T., Embry, K., & George, R. (2013). Diagnosis and management of acute diverticulitis. American family physician, 87(9), 612–620. https://pubmed.ncbi.nlm.nih.gov/23668524/