Answer

Soluble

Explanation

Psyllium is a type of dietary fiber that is known for its ability to absorb water and become gelatinous. This characteristic allows it to bind with fats and sugars in the digestive system, which can help to slow their absorption into the bloodstream. This process is beneficial for managing blood cholesterol and blood sugar levels. Soluble fiber, which is what psyllium is, dissolves in water and forms a gel-like substance that can help to lower cholesterol and regulate blood sugar levels. Insoluble fiber, in contrast, does not dissolve in water and is mainly helpful for adding bulk to the stool and supporting regular bowel movements. Given the context of the question, which highlights the improvement of blood cholesterol and blood sugar, the correct type of fiber is soluble.