Name a major role of dietary fiber in nutrition.

Dietary fiber plays a major role in nutrition primarily by aiding in digestion and helping to prevent constipation. This is due to its ability to absorb water, which increases stool bulk and promotes regular bowel movements. By ensuring a well-functioning digestive system, fiber helps maintain gut health and can prevent issues such as constipation and diverticular disease. Additionally, fiber can help regulate blood sugar levels by slowing the absorption of sugar, which further contributes to digestive health.

The other options mention functions that are not directly related to dietary fiber. For instance, muscle recovery post-exercise is typically dependent on protein intake, rather than fiber. Similarly, vitamin D synthesis occurs primarily through skin exposure to sunlight and dietary sources, not directly influenced by dietary fiber. Lastly, the enhancement of fat absorption is primarily a function of dietary fats and not related to fiber intake. Thus, recognizing the significant role of dietary fiber in digestion highlights its importance in a balanced diet.