Final answer:
Fiber is beneficial in managing constipation and diarrhea because it can absorb water, stimulate intestinal contractions, and normalize intestinal transit time. It effectively helps to regulate digestive system processes, whether to alleviate constipation by moving stool through the colon or to absorb excess water in the case of diarrhea.
Step-by-step explanation:
Fiber is highly beneficial in the management of constipation and diarrhea due to its multifaceted role in the digestive system. The correct answer to the question is 'D. Do all of the above.' This is because fiber has the capacity to:
- Absorb water, which adds bulk to stool in the case of diarrhea and softens stool in the case of constipation,
- Stimulate intestinal contractions, which helps to move stool through the colon, easing constipation,
- Normalize intestinal transit time, balancing the process whether the issue is constipation or diarrhea.
Fiber can be both soluble and insoluble. Soluble fiber forms a gel-like substance that regulates the pace at which food leaves the stomach and enters the intestine, while insoluble fiber increases bulk and promotes the movement of material through the digestive system. Fiber's role extends beyond just easing bowel movements; it can also reduce the absorption of unhealthy substances like cholesterol, thus providing wider health benefits.