NANP Board Practice Exam

Which characteristic applies to lignin?

1. It is a carbohydrate and insoluble dietary fiber

2. It is not a carbohydrate but is considered an insoluble dietary fiber

3. It is a protein and soluble dietary fiber

4. It is a carbohydrate and soluble dietary fiber

The correct answer is: It is not a carbohydrate but is considered an insoluble dietary fiber

Lignin is a structural component found in the cell walls of plants. While it shares some similarities with carbohydrates and dietary fiber, it is not technically classified as either. Lignin is not a carbohydrate, which is defined as any organic compound made up of carbon, hydrogen, and oxygen, and it is not a dietary fiber, which is a type of non-digestible carbohydrate that promotes intestinal health. Lignin is considered insoluble dietary fiber because it does not dissolve in water and cannot be broken down by the body's enzymes. Therefore, option B is the best fit for the characteristic of lignin. Option A incorrectly identifies lignin as a carbohydrate, which is incorrect. Option C incorrectly identifies lignin as a protein, which is also incorrect. Option D incorrectly identifies lignin as a carbohydrate and soluble dietary fiber, which is only partially correct since lignin is not a carbohydrate.