A substance found in foods that come from plants. Fiber helps in the digestive process and is thought to lower cholesterol and help control blood glucose. The two types of fiber in food are soluble and insoluble. Soluble fiber, found in beans, fruits, and oat products, dissolves in water and is thought to help lower blood fats and blood glucose. Insoluble fiber, found in whole-grain products and vegetables, passes directly through the digestive system, helping to rid the body of waste products and possibly prevent diseases such as colon cancer.