Many foods contain calcium but dairy products are the most significant source. Milk and dairy products such as yogurt , cheeses, and buttermilk contain a more efficiently-absorbed form of calcium. Soluble fiber attracts water and turns to gel during digestion. This slows digestion and the rate of nutrient absorption from the stomach and intestine. It is found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables.
Insoluble fiber is found in foods such as wheat bran, vegetables and whole grains.
It appears to speed the passage of foods through the stomach and intestines and adds bulk to the stool. A diet high in fiber has been shown to reduce the risk of cancers of the rectum and colon. Since fiber speeds up the passage of food through the digestive tract, it may help prevent exposure to cancer causing agents in the food. Eating more fruits and vegetables helps provide a good supply of fiber, vitamin A , vitamin C and beta-carotene . Beta carotene is a precursor to vitamin A. Beta-carotene and vitamin C may protect against cancer through their antioxidant effect.