What is the primary source of dietary fiber?

What is the primary source of dietary fiber?

• A. Cellulose
• B. Starch
• C. Glycogen
• D. Lactose

Answer: (A)

Dietary fiber means plant carbohydrates that humans can’t digest. The principal fiber in foods is cellulose, the structural polysaccharide in plant cell walls. Its glucose units are linked by beta-1,4 bonds, which our enzymes can’t break, so cellulose stays largely intact as it moves through the digestive tract. This insoluble fiber adds bulk to stool and helps keep digestion regular, which is why it’s considered the main source of dietary fiber. In contrast, starch and glycogen are digestible energy carbohydrates, and lactose is a milk sugar; they are broken down and absorbed rather than functioning as dietary fiber.

Dietary fiber means plant carbohydrates that humans can’t digest. The principal fiber in foods is cellulose, the structural polysaccharide in plant cell walls. Its glucose units are linked by beta-1,4 bonds, which our enzymes can’t break, so cellulose stays largely intact as it moves through the digestive tract. This insoluble fiber adds bulk to stool and helps keep digestion regular, which is why it’s considered the main source of dietary fiber. In contrast, starch and glycogen are digestible energy carbohydrates, and lactose is a milk sugar; they are broken down and absorbed rather than functioning as dietary fiber.