Sep 13, 2026 · 57 min · 18 segments
Fiber is making a comeback—and scientists are discovering that its role in human health goes far beyond keeping us regular. In this episode of Chasing Eden, Caroline Thompson explores why Americans…
Carolyn ThompsonHost
Broadly speaking, dietary fibers are carbohydrates found primarily in plant foods that aren't completely digested and absorbed into the small intestine the way sugars and many starches are.
Instead, much of that material continues toward the large intestine, But calling all of it simply fiber can be misleading because fibers can behave very differently.
You've probably heard fiber divided into two categories, soluble and insoluble.
That's useful, although modern nutritional science also classifies fibers according to characteristics such as viscosity and fermentability.
As the name suggests, soluble fiber can interact with water, some soluble fibers from viscous gel-like material inside the digestive tract.
Sources include foods such as oats, barley, beans, lentils, peas, apples, citrus fruits, carrots, and psyllium.
These viscous fibers can slow the movement of nutrients through the parts of the digestive process.
You'll find it in foods including wheat bran, many whole grains, vegetable skins, nuts and seeds.
But there's another characteristic that's arguably even more fascinating, and that's called fermentability.
Those microbes break them down and produce metabolites, including the short-chain fatty acids I mentioned earlier.
A prebiotic, on the other hand, is a substrate selectively used by microorganisms that can confer a health benefit.
Foods containing prebiotic compounds include onions, garlic, leeks, asparagus, chicory, Jerusalem artichokes, legumes, and certain whole grains.
This starch that resists digestion in the small intestine and reaches the large intestine where microbes can ferment it.
Broadly speaking, dietary fibers are carbohydrates found primarily in plant foods that aren't completely digested and absorbed into the small intestine the way sugars and many starches are.
Instead, much of that material continues toward the large intestine, But calling all of it simply fiber can be misleading because fibers can behave very differently.
You've probably heard fiber divided into two categories, soluble and insoluble.
That's useful, although modern nutritional science also classifies fibers according to characteristics such as viscosity and fermentability.
As the name suggests, soluble fiber can interact with water, some soluble fibers from viscous gel-like material inside the digestive tract.
Sources include foods such as oats, barley, beans, lentils, peas, apples, citrus fruits, carrots, and psyllium.
These viscous fibers can slow the movement of nutrients through the parts of the digestive process.
You'll find it in foods including wheat bran, many whole grains, vegetable skins, nuts and seeds.
But there's another characteristic that's arguably even more fascinating, and that's called fermentability.
Those microbes break them down and produce metabolites, including the short-chain fatty acids I mentioned earlier.
A prebiotic, on the other hand, is a substrate selectively used by microorganisms that can confer a health benefit.
Foods containing prebiotic compounds include onions, garlic, leeks, asparagus, chicory, Jerusalem artichokes, legumes, and certain whole grains.
This starch that resists digestion in the small intestine and reaches the large intestine where microbes can ferment it.
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