The Regulatory Importance of Fibers
These are some of my favorite delicious, fiber-rich foods. You can see some of my recipes to see how I prepare them!
From oats to black beans to chia seeds: fiber is everywhere. We consume it in every meal we eat, with apparent good reason! But do people really know that reason? Whether you do or don’t, I hope to help clarify the complexities of fiber’s importance!
What is fiber? It’s a carbohydrate or a compound comprised of a string of sugars. The exact structure of a fiber is called a polysaccharide, simply meaning “many sugars”. Between each sugar, there is a glycosidic linkage: a covalent bond. Now, not all carbs are fibers, but all fibers are carbs. The structural and functional identity of fiber is defined by the spatial arrangement of the glycosidic linkage.
Before we continue with the definition of fibers, it’s vital to understand hydrolysis. By definition, hydrolysis is the addition of water to a molecule to another molecule, wherein turn the already existing molecule will be broken down. The easiest example of this exergonic chemical reaction would be noticing how when you put salt into water, the salt will dissolve.
So when humans eat carbs, they will interact with proteins that are also known as enzymes inside the body. Enzymes are the dock for carbs to latch onto, where then the enzyme will essentially promote the interaction of a water molecule and the carbohydrate: hydrolysis of the carb. With simple polysaccharides, it will be hydrolyzed down into a bunch of singular sugar molecules, where at that point, the body has digested them and will put them towards creating new energy in the body. However, it’s not that simple for fibers.
This is where the importance of the spatial arrangement of the glycosidic linkages comes into play. In fibers, because each glycosidic linkage isn’t facing the same way, the enzyme won’t fit! The key doesn’t fit inside the lock. So no hydrolysis, no digestion! What is happening with these molecules if they aren’t being digested?
The fibers will remain intact inside the body until it reaches the large intestine, more commonly known as the colon. Inside the colon, there are colonic bacteria. Unlike some dangerous bacterias, colonic bacteria are vital to human digestion. These bacteria are able to dock onto the fiber polysaccharides which will ferment them through anaerobic respiration, which is cellular respiration without the presents of oxygen. This will then allow the fiber to be expelled from the body. However, there is a symbiotic relationship here. This helps regulate the reproduction of colonic bacteria, so in the future, the colon will have more bacteria to break down more fiber!
At large, fiber promotes a healthy regulation of bacteria inside the colon, which regulates digestive tract health. However, this is only promoted if you eat a sizable amount of fiber and keep it consistent.
Citations
https://ask.usda.gov/s/article/How-much-dietary-fiber-should-I-eat
Nutrition: Concepts and Controversies 15th edition, CENGAGE Learning
