Fiber is something the body needs but never actually digests, and comes in two varieties, soluble and insoluble, and most plant-based foods contain a mixture of the two. Soluble fiber turns to gel in the stomach and slows digestion, which helps lower cholesterol and blood glucose. Insoluble fiber remains unchanged all the way to the colon, making waste heavier and softer so it can move through the intestines more easily.
Skipping fiber in the diet often leads to constipation and eating too little fiber can make it tough to control blood sugar and appetite because fiber regulates the speed of digestion and contributes to feeling full. Over eating fiber can move food through the intestines too quickly, which means fewer minerals get absorbed from food, and can result in gas, bloating and possible cramping.
The Institute of Medicine recommends:
Men (under 50): 38 grams (over 50): 30 grams
Women (under 50): 25 grams (over 50: 21 grams