Nutrition is classified as a field of health sciences concerned with providing the human body with its nutritional needs of essential elements for life, supplied by various types of food to enable it to perform its functions fully through numerous internal biological reactions, ensuring its structural integrity. The body needs to consume different nutrients, each performing indispensable functions throughout life, either alone or in conjunction with others. Nutrients are the six nutritional elements found in food. Three are macronutrients—proteins, carbohydrates, and fats—which the body needs in large quantities. The body also requires very small amounts of other elements like vitamins and minerals, and the final element is water, which the body needs freely. Some nutrients can be used directly, while others must be converted into simple components. Additionally, the body can synthesize some nutrients if they are unavailable in the diet, relying on other essential nutrients. This explains the great diversity and integration among the different nutrients that characterize food sources, allowing for choices to cover all nutritional needs for the body's safety and composition, which vary according to life stages.

Therefore, one of the main interests of nutrition is the structural properties of nutrients and their vital functions, as well as the optimal conditions for their best use and return. This includes providing energy, completing building and growth processes, maintaining and renewing tissues, and their functional role in biological reaction pathways, in addition to protecting against certain diseases to ensure health and activity. Nutrition is concerned with the body's needs for various nutrients, quantitatively and qualitatively, according to age groups, gender, and physical activity levels, known as the Recommended Dietary Allowances (RDA). It also focuses on the journey of food within the body, from digestion in the gastrointestinal tract, which breaks down complex components into simple ones, to absorption and transport to tissue cells where nutritional metabolism begins. This includes the relationship between nutrients in both healthy states and in cases of nutritional imbalance, where accumulated intermediate products can negatively affect the body's condition and threaten its safety and life. A key area of nutrition is also addressing the adverse symptoms resulting from insufficient nutrient intake (malnutrition) or excessive intake (over-nutrition), which can lead to conditions like obesity and related diseases in both children and adults.

One of the important practical applications of nutrition science is planning meals to achieve proper nutrition by ensuring a balanced diet. This means creating simple, easy-to-follow balanced dietary systems for individuals of all ages, so that it becomes an ingrained habit in their daily meals. Another practical goal is to study the nutritional status of individuals and groups to assess the effects of prevailing dietary patterns and habits. This allows for a sound judgment on health indicators linked to good nutritional behaviors, or to identify nutritional problems and their causes in order to modify environmental conditions and behaviors to solve these issues safely, while protecting against the risk of deterioration that could threaten human life.

• Number of Pages: 520
• Year of Publication: 2017