Fiber refers to nondigestible carbohydrates — those that aren’t broken down and absorbed in your digestive tract for energy.
Eating fiber, specifically soluble fiber, can lower LDL cholesterol levels.Soluble fiber forms a gel-like substance in your intestines, slowing down digestion.
It also traps cholesterol and prevents your body from reabsorbing it into your bloodstream. The trapped cholesterol is then excreted from your body in stool
In addition, bacteria living in your large intestine ferment, or feed on, soluble fiber.This fermentation not only helps create a healthy gut that promotes the excretion of cholesterol
but also produces short-chain fatty acids (SCFAs). Absorption of SCFAs decreases cholesterol synthesis in your liver, which also lowers blood cholesterol
However, insoluble fiber does not lower cholesterol like soluble fiber does. Insoluble fibers don’t form a gel and resist fermentation by gut bacteria.
Instead, they add bulk to the stool, speed up digestion, and contribute to health in other ways.
The 2020–2025 Dietary Guidelines for Americans advise that women should generally consume 25–28 grams of fiber per day
and men should aim for 31–34 grams of fiber. That’s about 14 grams of fiber for every 1,000 calories consumed
For most Americans, the range of 25–35 grams of fiber per day would be considered increased consumption, with soluble fiber composing at least 6 grams of that amount
Regular consumption of soluble fiber is associated with a 5–10% reduction in total cholesterol and LDL cholesterol levels
But some food sources of soluble fiber may be more effective at lowering cholesterol than others.Soluble is effective at lowering total and LDL cholesterol levels
by decreasing the synthesis of cholesterol in the body and by helping to increase excretion. Insoluble fiber does not have that same effect.