This naturally-occurring nutrient is neither digested nor absorbed by humans. Instead, this nutrient encourages the growth of bifidobacteria (a beneficial strain of colonic bacteria) while suppressing the growth of potentially harmful organisms in the colon. In addition, this nutrient helps relieve constipation and enhances intestinal immunomodulation. Regular intake of foods rich in this nutrient may also help reduce the risk of colon cancer. What is the name of this nutrient?