Fiber is not necessarily fibrous

Fiber is not necessarily fibrous

December 29, 2022
nutrition, semantics

In nutrition science, the word fiber refers to the type of carbohydrate that the body can’t digest. This definition of fiber is so different from the kind of fiber found in many plants that they might as well be completely different words.


Coconut coir fibers are obtained from the outermost layer of the husk. They are typically light brown in color, durable, and resistant to water.

coconut coir

Credit: Midjourney

Indeed, these are a kind of fiber that your body cannot digest. You cannot digest banana peals either. In nutrition science, the word fiber refers to appetizing carbohydrates that the body can’t digest. Some of the highest fiber foods are not fibrous:

food source grams of fiber
1 cup cooked lentils 15
raw avocado flesh from a medium avocado 10
1 cup cooked rolled oats 4
1 tablespoon chia seeds 5

So whenever you hear the word fiber in a nutrition context, picture slimy gel instead of coconut coir. Also, you should always prefer fermentable fiber. Just because you cannot digest fiber doesn’t mean that the friendly bateria in your gut can’t. For example, avoid psyllium fiber (e.g., Metamucil) because it is not fermentable.1

Notes #

  1. Hu, G. X., Chen, G. R., Xu, H., Ge, R. S., & Lin, J. (2010). Activation of the AMP activated protein kinase by short-chain fatty acids is the main mechanism underlying the beneficial effect of a high fiber diet on the metabolic syndrome. Medical Hypotheses, 74(1), 123–126. ↩︎