Question

Which of the following statements about dietary fiber is/are correct? A. Water-soluble fiber helps to lower serum cholesterol in most people. B. Mucilaginous fiber slows the rate of digestion and absorption of carbohydrates. C. Insoluble fiber increases stool bulk and decreases transit time. D. All of the above. E. None of the above.

Short answer

A) Water-soluble fiber helps to lower serum cholesterol in most people. B) Mucilaginous fiber slows the rate of digestion and absorption of carbohydrates. C) Insoluble fiber increases stool bulk and decreases transit time. D) All of the above E) None of the above Answer: D) All of the above

Step-by-step solution

Understand Types of Dietary Fibers

First, we need to know the types of dietary fibers and their functions. There are two main types of dietary fibers: soluble and insoluble fibers. Soluble fibers dissolve in water to form a gel-like substance, while insoluble fibers do not dissolve in water and help in maintaining regular bowel movements. Mucilaginous fibers are a type of soluble fiber found in specific plant-based foods.

Evaluate Statement A

Statement A says that "Water-soluble fiber helps to lower serum cholesterol in most people." Indeed, water-soluble fiber can help lower cholesterol levels in the blood by binding with bile acids, which are then expelled from the body, leading to cholesterol reduction. So, statement A is correct.

Evaluate Statement B

Statement B says that "Mucilaginous fiber slows the rate of digestion and absorption of carbohydrates." This statement is also correct, as mucilaginous fibers slow down the process of digestion, which helps control the rate of carbohydrate absorption into the bloodstream. This can be beneficial in regulating blood sugar levels.

Evaluate Statement C

Statement C states, "Insoluble fiber increases stool bulk and decreases transit time." Insoluble fibers absorb water and create a bulk in the stool, which makes bowel movement easier and faster. So, the statement is accurate.

Evaluate Statement D and E

As all statements A, B, and C are correct, statement D (All of the above) is the right answer, and statement E (None of the above) would be incorrect. The correct answer is D. All of the above statements are accurate concerning dietary fiber.

Key concepts

Soluble and Insoluble Fibers

Understanding the two main types of dietary fibers—soluble and insoluble—is key to appreciating their health benefits. Soluble fibers are known for their ability to dissolve in water, forming a gel-like consistency. They are found in various foods, including fruits like apples and citrus, vegetables, legumes, oats, and barley. These fibers bind with fatty acids, prolonging stomach emptying time, which may help you feel full for longer.

Insoluble fibers, on the other hand, are found in foods such as whole grains, wheat bran, nuts, and vegetables. These do not dissolve in water and instead add bulk to the diet. This type of fiber is predominantly beneficial for those struggling with irregular stools, as it helps to maintain regular bowel movements and can prevent constipation by accelerating the movement of food through the digestive system.

Lower Serum Cholesterol

One of the notable benefits of soluble dietary fiber is its potential to lower serum cholesterol, an important factor in cardiovascular health. Soluble fiber interferes with the absorption of dietary cholesterol and bile acids. These bile acids, necessary for the digestion of fats, are bound by the soluble fiber and consequently eliminated from the body. This prompts the liver to produce more bile acids, using up cholesterol in the bloodstream and thus reducing its overall levels.

Diets rich in soluble fiber from sources such as beans, flaxseeds, oat bran, and certain fruits have been associated with improved lipid profiles, including reduced levels of low-density lipoprotein (LDL) cholesterol—the so-called 'bad' cholesterol.

Digestion and Absorption of Carbohydrates

Dietary fibers can significantly influence the digestion and absorption of carbohydrates. Soluble fibers, particularly mucilaginous fibers found in plants like okra and seaweeds, can slow down the digestive process. This results in a more gradual absorption of carbohydrates, which helps to prevent spikes in blood sugar levels following meals.

Consistent blood sugar levels are crucial for managing conditions such as diabetes. Moreover, the slower absorption rate of carbohydrates aids in maintaining long-term energy supply and can reduce the incidence of hunger pangs, assisting in weight management efforts.

Stool Bulk and Transit Time

Insoluble fiber has a crucial role in managing the body’s waste removal process. As it absorbs water, it increases the stool bulk, making stools softer and larger. A higher stool bulk is easier for the intestinals muscles to move along, hence reducing the so-called 'transit time.' Faster transit time is beneficial because it reduces the time waste substances stay in contact with the intestinal walls.

By increasing stool bulk and speeding up transit time, insoluble fiber can help prevent common digestive issues such as constipation and promote a healthier gastrointestinal tract. Including adequate amounts of insoluble fiber in the diet also supports the prevention of certain bowel disorders, including diverticulitis and hemorrhoids.