Insoluble fiber refers to dietary fiber that does not dissolve in water.
Insoluble fiber is neither dissolved nor fermented in the intestine, allowing for an increase in bulk and transit time of bowel movements. Insoluble fiber has been seen to reduce appetite, food intake, and blood sugar increases in response to meals consumed later. It also regulates blood sugar increases immediately after consumption of the fiber-rich meal.
High insoluble fiber diets, when not accompanied by adequate liquid consumption, may cause constipation.
Whole grains, bran, nuts, seeds, vegetables, fruit, legumes, skins of root vegetables
Food and Agriculture Organization of the United Nations
The American Journal of Clinical Nutrition
Biological and Pharmaceutical Bulletin