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The Need for Food
Living organisms require food because it contains the needed energy and materials essential to maintain life. The energy stored in food is required for the vital activities of any living organism, such as movement, growth, and development, repair of worn-out tissues, reproduction, and synthesis of new protoplasm. Food is the source of materials needed to maintain health and prevent disease.
Nutrients in Food
Nutrients are molecules found in foods that nourish the body by providing energy and materials essential for growth and development. Nutrients include carbohydrates, Proteins, fats, vitamins, minerals, water, and fibers.
Carbohydrates
Carbohydrates are the main source of energy. They come mainly from plants in the form of sugars, starch, and cellulose. Plants produce and store these carbohydrates in their seeds, fruits, and roots. Foods rich in carbohydrates include rice, bread, and cereals. Aside from a good source of energy, carbohydrates play other supporting structures, such as the cellulose plant cells. It is also needed in the formation of nucleic acids.
Proteins
Amino acid, the building blocks of proteins, are essential for the formation of new protoplasm, for growth, and repair of worn-out body cells. Proteins are used for synthesis of enzymes, hormones, and antibodies to combat diseases. It could also be used as an energy source. Most plants and some unicellular organisms are capable of producing all the twenty essential amino acids. Some plants, however,lack one or more essential amino acids. Among humans, eight of these essential amino acids cannot be synthesized and, therefore, must be supplied by the food we eat. These amino acids include menthionine, tryptophan, leucine, and phenylalanine. A deficiency of any of these essential amino acids will result in the inability of certain enzymes or hormones to be synthesized.
Fats
Fats are also energy-providing foods. In fact, fats provide twice as much energy per gram as carbohydrates. Eating fat-rich food is an excellent way of storing energy for future use. Too much fats could have severe consequences, however, as it could accumulate in the walls of blood vessels resulting in a disease called arteriosclerosis. Foods rich in fats include butter, cheese, fatty meat, nuts, leguminous plants, and fish liver. Human are capable of manufacturing their own fat requirement, thus fat is not essential in the diet.
Vitamins
Vitamins are complex organic molecules needed in small amounts and cannot be manufactured by the human body. Only vitamin D can be synthesized in the skin under direct sunlight. Vitamins maybe fat-soluble vitamins or water-soluble vitamins. Fat-soluble vitamins can be stored in the fats of the body, while water-soluble vitamins cannot be stored in the body and must be supplied in the daily diet. Fat-soluble vitamins include vitamins A, D, E, and K. Most vitamins function as cofactors or coenzymes to promote or asst enzymes in catalyzing a particular chemical reaction. Fruit, vegetables, and meats are good sources of vitamins.
Minerals
Minerals are inorganic substances which do not provide energy but are important in different body functions. Some minerals are needed by the body in large amounts but others are required in small quantities. Calcium, sodium, chlorine, phosphorus, potassium, and iron are needed by humans and some mammals in large amounts. Calcium for example is required in building bones and teeth, for normal muscles functions, and for blood clotting. About one gram of calcium is needed by children per day but slightly less is needed among adults, except by pregnant and lactating mothers. Minerals needed by the body in small amounts are called trace elements. Iodine, manganese, and zinc are examples of trace elements.
Water
Man can survive longer without food but not without water! Human and most mammals are made up of about 70% water. Water is the biological solvent and protoplasms of our cells are made up mainly of water. Fruits and vegetables are good sources of highly purified water. Water is lost constantly from the body during breathing, through sweat, in the urine and in feces. To compensate for the water lost, one must drink plenty of waters and eat succulent food. It is recommended to drink at least 8 glasses of water a day or everyday. In tropical countries like the Philippines, one should drink more than what is recommended in temperature countries. The amount of water needed by the body is depends on the activity of the person and the environmental conditions.
Fiber
Fiber or roughage refers to the indigestible fibrous material found in vegetables and fruits. These fibrous materials are made up mainly of cellulose. Fresh vegetables, fruits, bran, cereals, and wholewheat bread are good sources of dietary fiber. Fibers do not provide us with energy or nutrients but it is important because it provide bulk to the intestinal contents and helps peristalsis, and help the food to move along the gut.
Diet and Health
To have a good and healthy body and to have a good and normal growth development, we need to have a balanced diet. Balancing what we eat and what we are doing can be the factor to have a healthy body. Balance diets means to have a right amount of nutrients like the carbohydrates, fats, vitamins, minerals, water, and fiber to store or supply energy. However, that amount of nutrients required varies on the person depending to his/her situation like the health conditions, lifestyle, activities, sex and age.
Exercise can also contribute to give us healthy body. With proper training, workouts and exercise you can easily achieve healthy body and it also maintain the physical fitness and overall health of yours. To enjoy the glow of good health, we need to exercise.
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I hope you learn something from me...
The greatest wealth is health
Reference
BIOLOGY Ramos and Morales-Ramos