How Food Works in the Body

Variety

Nourishing the body helps a person maintain both physical and mental health. Healthy eating also reduces the risk of diseases such as diabetes, heart disease and cancer. Variety is the key to getting an adequate intake of all the essential vitamins and minerals your body needs. Food is fuel, therefore, eating well-balanced meals provides you with the nutrients required to keep you performing at your best. Fruits and vegetables are low in calories and contain the fiber, vitamins and minerals the body needs to prevent diseases, break food down into energy, build strong bones and teeth, and control the body's fluid balance. Starchy vegetables and whole grains provide the carbohydrates, which are burned as the body's primary source of fuel. The right kinds of fats in the appropriate amounts are needed to provide the body with energy, absorb the fat-soluble vitamins, help transmit nerve impulses and transport nutrients across cell membranes. Protein from fish, lean meats, eggs, poultry and dairy foods is essential for growth and to build and repair the body's muscles and tissues.

Digestion

According to the American Medical Association, the digestive system is made up of organs that break down food so that the body can use nutrients for energy and to build and repair cells. Digestion actually begins in the mouth as you chew and then swallow food. These smaller particles of food are then pushed down the throat into the esophagus. Food passes through to the stomach where it is mixed with digestive juices before entering into the small intestine. The time it takes the stomach to empty its contents depends on whether carbohydrates, protein or fats are being digested. Although protein stays in the stomach longer than carbohydrates, fats take the longest time to digest. As food is pushed forward through the small intestine, or small bowel, it is dissolved more in juices produced by the pancreas, liver and lining of the intestine. Once food is completely digested, nutrients are absorbed through the walls of the small intestine into the bloodstream so that they can be transported to the body's cells and tissues.

Nutrients

The body breaks starch and sugar from carbohydrates down into glucose molecules, which are carried by the blood to the liver where glucose is either used for energy or stored as glycogen for later use. During digestion, protein is broken down into smaller molecules known as amino acids, which play a vital role in most of the body's functions. Bile from the liver and enzymes produced by the pancreas and intestine work to dissolve fat and break it down into smaller molecules so that it can be absorbed into the cells of the intestine where it is converted into triglycerides and stored for energy. Vitamins, too, are absorbed through the small intestine. Water-soluble vitamins such as the B vitamins and vitamin C are not easily stored by the body and must be constantly replenished. Any amounts of these vitamins that are not used are excreted from the body through urine. Fat-soluble vitamins like vitamins A, D, E and K are stored in the liver and fatty tissue of the body.

Hormones/Nerve Regulators

Like most of the body's other fundamental processes, hormones regulate digestion. These chemical messengers send instructions to the body's cells as they are released into the bloodstream. The hormones gastrin, secretin and CCK secreted by the mucous membrane of the small intestine stimulate the production of digestive juices and initiate peristalsis, the smooth muscle contractions that move food through the digestive tract. The nerve regulator acetylcholine triggers the digestive organs to push food through the digestive tract. The brain then releases adrenaline to slow or stop digestion.