Written by Golp Editorial Team·Sourced from FDA, USDA, NIH, and peer-reviewed US research·Updated August 2026·1 min read
Short answer
Soluble fiber dissolves in water and is linked to lower cholesterol and better blood sugar control, according to NIH†. Insoluble fiber doesn't dissolve and adds bulk that helps move food through the digestive tract. Most whole foods contain a mix of both.
Why it matters
These two fiber types do genuinely different jobs in the body. Getting a mix of both, rather than focusing on one, covers more of what fiber is generally understood to support.
What the evidence says
According to NIH research summaries, soluble fiber, found in oats, legumes, and some fruits, mixes with water and slows digestion, associated with decreased cholesterol and better blood sugar control†. Insoluble fiber, found in whole grains, bean skins, and root vegetables, acts as bulk that helps food and waste move through the gut more easily.
The golp take
You don't need to track soluble versus insoluble separately day to day. Eating a genuine variety of plant foods generally covers both without needing to calculate it.
What to do
Include both a grain source and a legume or vegetable source in most meals, this naturally covers both types
Oats and legumes are common soluble fiber sources per NIH; whole grains and vegetable skins are common insoluble sources
Don't over-optimize for one type at the expense of overall intake
