The colon, also known as the large intestine, is a tube-shaped organ that's part of the digestive system. It's responsible for absorbing water and nutrients from food, and passing waste to the rectum. Function >Absorbs nutrients The colon absorbs water, electrolytes, and some nutrients from partially digested food. >Stores waste The colon stores solid waste, called stool, until it's ready to be passed out of the body. >Produces vitamins The colon contains bacteria that produce vitamins B and K,