Question:medium
Dietary fibers are degraded by colonic bacteria to form which of the following?
Dietary fibers are degraded by colonic bacteria to form which of the following?
Show Hint
Colonic bacteria ferment fiber into short-chain fatty acids; butyrate feeds the colon cells.
Updated On: Jul 8, 2026
- Butyrates
- Glycerol
- Sucrose
- Free radicals
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Remember what fiber is.
Dietary fiber is plant carbohydrate that human digestive enzymes cannot break down, so it travels intact from the small intestine into the colon.
Step 2: Bring in the colonic bacteria.
Once fiber reaches the colon, resident bacteria ferment it in a low-oxygen environment. This fermentation splits fiber into short-chain fatty acids, chiefly acetate, propionate, and butyrate.
Step 3: See why butyrate stands out.
Among these, butyrate is absorbed straight by the colon lining cells and burned as their preferred energy source, ahead of glucose. This is why a fiber-rich diet is often linked to a healthier colon lining.
Step 4: Eliminate the distractors.
Glycerol comes from breaking down fats, sucrose is a dietary sugar absorbed earlier in the gut, and free radicals are oxidative byproducts, none of which is the direct output of bacterial fiber fermentation.
Step 5: Conclude.
$\boxed{\text{Butyrates}}$
Dietary fiber is plant carbohydrate that human digestive enzymes cannot break down, so it travels intact from the small intestine into the colon.
Step 2: Bring in the colonic bacteria.
Once fiber reaches the colon, resident bacteria ferment it in a low-oxygen environment. This fermentation splits fiber into short-chain fatty acids, chiefly acetate, propionate, and butyrate.
Step 3: See why butyrate stands out.
Among these, butyrate is absorbed straight by the colon lining cells and burned as their preferred energy source, ahead of glucose. This is why a fiber-rich diet is often linked to a healthier colon lining.
Step 4: Eliminate the distractors.
Glycerol comes from breaking down fats, sucrose is a dietary sugar absorbed earlier in the gut, and free radicals are oxidative byproducts, none of which is the direct output of bacterial fiber fermentation.
Step 5: Conclude.
$\boxed{\text{Butyrates}}$
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