Which of the following is a characteristic of soluble fiber?

• A. Dissolves in stomach fluids
• B. Not digested by humans
• C. Increases cholesterol absorption
• D. Reduces water absorption

Answer: (A)

Soluble fiber dissolves in water to form a gel-like substance. This ability to dissolve in stomach and intestinal fluids is a defining feature, and that gel can slow digestion and the absorption of nutrients, including sugars and cholesterol. That makes it the best match for a characteristic of soluble fiber.

In addition, soluble fiber is not digested by human enzymes, which is true for dietary fiber in general, but the dissolving-in-fluid property is the most distinctive trait. It does not increase cholesterol absorption; in fact, it can help lower cholesterol by binding bile acids. It also tends to retain water, helping to soften stools rather than reduce water content.