The food we take is first converted to chemical energy before being converted into other forms of energy that are necessary for the maintenance of normal body functions. These functions are divided to two main processes, building process and breakdown process. 50–60 percent of energy in our bodies is allocated for growth, stabilization of body temperature and development of basic body needs. A healthy diet should provide enough energy to meet these requirements. It should be sufficient, adequately balanced and various. Such an adequate diet provides efficient growth. Energy obtained from food is converted into bio-electrical energy, which powers the activities of the nervous system, heart contraction and muscular contraction. Some of that energy is converted into thermal energy to maintain body temperature, or chemical energy to allow synthesis of new molecules. The main energy provider is carbohydrates that can be found in grains, fructose, cereals, flours, lactose, sucrose, beans and vegetables. They cannot be replaced by other nutrients, except lactose milk sugars and starch in infants. Proteins are also important in a diet; they are crucial for growth and tissues repair. Sources of protein include meat, dairy and eggs. Lipids are another element that should be covered in any diet; they are rich in triglycerides and considered as a source of concentrated energy. They play a role in the development of the brain and eyes. Lipids are a source of fat soluble vitamins that are found in vegetable oil, cream, butter, cheese, egg yolk, meat and dry fruits. Macro minerals like calcium, phosphorus and sodium are important for the optimum function of several body mechanisms. While micro minerals like iodine, iron and fluoride are needed in very minute quantities. Trace elements like selenium, chromium and nickel are necessary for tissues formation hormones and the catalization of enzyme activities. They are also essential for growth and development. Calcium: It is needed for bones, teeth, muscles, heart contraction, nerve excitation and blood clotting. Sources of calcium include breast milk for infants, whole milk, yogurt and cheese for children and adults. Still, only 15 – 25 percent of the calcium ingested is actually absorbed. Iron is essential for blood formation and other enzymatic functions. Diets should contain 10-20 milligrams of iron. Eight to ten percent of iron in ingested food is absorbed. Fifty percent of iron present in breast milk is absorbed while only ten percent of that in cow milk is absorbed. That is why unmodified cow milk is not recommended until 1 year of age. Magnesium is essential for all enzymatic reaction, neuromuscular excitability, bone and dental development. Phosphorus is also essential for bone and teeth formation. It combines with fat in brain formation and in release of energy. Copper is significant for connective tissues formation and skin pigmentation. Iodine is important for thyroid function which is the band master of all metabolic process. Iodized table salt is the main source of iodine. Vitamins are organic compounds found in food; they are essential for growth, development and normal body functions. Vitamins are found in two forms, fat soluble form as in vitamins A, D, E, and K and water soluble B complex vitamins. Our bodies can manufacture vitamins D, K B1 and B12. Vitamin E serves as a first line of defense as an antioxidant, while vitamin K blood clotting. Most vitamins are available in the foods mentioned above. Water is the most essential requirement, constituting up to 70 percent of body weight in infants and 60 percent in children, while more than 50 percent of adult bodies are formed of water. The increased demand on water in childhood is due to continuous growth and weight gain. *The writer is a Pediatrician at My Care Medical Center with an M.B.B.S, DcH (Dublin) Ireland __
