Why vitamins and minerals can pass through the wall of the small intestine but fiber cannot?

Vitamins and minerals can pass through the wall of the small intestine because they are small, soluble molecules that can be absorbed directly into the bloodstream. In contrast, fiber consists of larger, complex carbohydrates that cannot be broken down by human digestive enzymes, preventing them from being absorbed. Instead, fiber moves through the digestive tract largely intact, aiding in digestion and promoting gut health. This difference in size and chemical structure is key to their absorption capabilities.