The human body is a complex, living, biological organism that is sustained by nutrients for its continued survival. Without these nutrients, the body breaks down from weakness and disease and eventually dies. Like any living organism, the human body has to be cared for by providing it with the means to maintain the energy it needs to keep its biological functions working.
Everything that the human body can do - seeing, touching, hearing, smelling, thinking, moving, reproducing, and so on - would depend on how well its smallest unit called the cell is nourished and maintained. Since the human body consists of some 60 trillion cells (Dunne, 2002, p. 135) that are grouped together into organs, each with its own function and purpose, the whole body will be healthy and able to live for a long period of time if the cells in the body are kept in good working condition. This is what nutrition is supposed to do, to keep each cell healthy and functioning properly. Nutrition provides the body with nutrients that are chemical substances necessary to keep the cell, and therefore the body, alive. There are six types of nutrients: carbohydrates, fats (or lipids), proteins, vitamins, minerals, and water. Each nutrient participates in at least one of the following functions: providing energy to the body, building and repairing body tissue, and regulating bodily processes.
Carbohydrates, proteins, and fats supply energy. Proteins also build and repair body tissues with the help of vitamins and minerals. Vitamins, minerals, and water help regulate the different body processes such as circulation, respiration, digestion, and elimination of waste. Each nutrient is important and none works alone.
Nutrients come from the food we eat, which the body must process before they can be used. What is known as nutrition is the whole series of processes where the body takes in and uses food for growth, development, and maintaining good bodily health. These processes - digestion, absorption, and metabolism - are very important and also need nutrients in order to be carried out properly.
Nutrition therefore includes the whole range of activities that starts with the food we eat (our diet), the nutrients contained in the food, and the process of digestion, absorption, and metabolism that break down the nutrients in our diet into chemicals that are sent to all the different cells in the human body. If we want the body to stay healthy, the whole nutrition process must be healthy. This begins with having a healthy diet or food intake.
What is a healthy diet This is what doctors, scientists, and health experts have been doing research all these years to determine. Several research studies show that what for us would be a healthy diet depends on many factors, such as our bodily state, age, level of activity, our lifestyles, the antibodies we have developed in our immune systems, and even the way we were nourished when we were still in our mother's womb and our cultural background (different people prefer potatoes, pasta, bread, rice, or noodles with their meat). There are countless definitions of what a healthy diet is. What may be healthy for bush men in the forests of Africa and Papua New Guinea (fresh worms, raw tuber roots, and boiled fish) may not be healthy for a young student living in Europe, and vice