Why cant fiber be broken down like other carbohydrates?
In: Biology
The simple answer is that if you want a big brain, you either need to be omnivorous or massive. Brains are incredibly expensive to feed, so you either need a diet that can capture a lot of energy quickly and efficiently, or be so huge that you can consume incredible amounts of low energy fiber and still break even. (larger bodies are more efficient as a rule).
We get energy by breaking our food down into very tiny pieces and then breaking those pieces apart strategically and capturing the energy it produces.
Starches sugars and fats are all ways of storing that energy in living organisms. We are efficient at moving, very clever, and have a high metabolic demand cause our brains are so big. So humans are built to range really far and look for caloric jackpots to plunder.
Fiber is not stored energy. It is rigid structures that are built to last. Fiber happens to be made of mostly the same elements as starches and sugars but that doesn’t matter. We don’t get any energy from elemental carbon, hydrogen and oxygen. We get energy from manipulating the bonds formed between them. Fiber has all of those bonds in the wrong spots and needs a lot of rearranging and cutting down before it’s in a place to give up what little energy it contains.
Fiber requires specific enzymes and a lot of time to break down – neither of which human bodies are designed for. Cows, on the other hand, can so if that was your question, then fiber can be broken down.
The sugar units in fiber are linked up in a way that our body cannot break down. It’s because our body does not produce enzymes that actually break fiber apart. However, some microbes in our intestine do break some fiber down so they can use that energy for themselves. Hope that helps 🙂
Humans are not herbivores. We did not evolve to produce the proper enzymes to break down cellulose directly, or have the gut bacteria and intestinal length needed to extract nutrients via hind gut fermentation. We are omnivores and evolved to eat a mix of vegetable matter and animal matter and as such only get certain things from both, but cannot get all we need from either.
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