1. Definition and Importance of Nutrition

A. Definition and Importance of Nutrition Science

1. Definition: Nutrition science is the study of the nutrients in food and the impact of diet on human health. It can also be defined as the process of ingesting, digesting, absorbing, utilizing, and metabolizing food substances, and the relationship of these processes to growth, development, aging, disease, and recovery.

2. Importance (for health maintenance): Nutrition is the foundation of life activities. It has an important impact on human growth, development, aging, disease, and recovery.

2.1 Nutrition is the material basis for human growth and development. The human body needs a large amount of nutrients for growth and development, such as protein, fat, carbohydrates, vitamins, and minerals.

2.2 Nutrition is the source of energy for the human body to maintain life activities. The human body's energy metabolism requires a large amount of nutrients, such as carbohydrates, fats, and proteins.

2.3 Nutrition is an important defense line for the human body to resist diseases. Good nutritional status can enhance the body's immunity and reduce the incidence of diseases.

2.4 Nutrition is an important guarantee for human rehabilitation. Good nutritional status can promote the body's rehabilitation and improve the quality of life.

3. Disease prevention: Understanding nutrition can help prevent a variety of diet-related diseases, such as heart disease, diabetes, obesity, and certain cancers.

4. Chronic disease management: Appropriate nutritional support can be used to manage chronic diseases.

B. Nutrition and Health

1. Individual health: The physical structure and function of an individual are directly affected by the quality of their diet.

2. Public health: Good nutrition is essential for the health and economy of the entire society.

3. Quality of life: Nutrition is directly related to quality of life, including weight control, energy levels, and overall well-being.

C. Classification and Functions of Nutrients

1. Essential nutrients: Introduces the five categories of essential nutrients (carbohydrates, fats, proteins, vitamins, minerals) and water.

2. Carbohydrates: Provide energy and are the main source of energy for the brain and red blood cells.

3. Fat: It is a high-density source of energy and is a necessary component of cell structure and hormone production.

4. Protein: It is the basic component of body tissues and is essential for the immune system, enzymes, and hormone function.

5. Vitamins and minerals: Support a variety of biological functions in the body, from bone health to vision.

6. Water: As an indispensable component of body function, it participates in temperature regulation, nutrient transport, and waste elimination.

2. Factors Affecting Nutrition

There are many factors that affect nutrition, including the following:

• Age: People of different ages have different nutrient needs. Infants, young children, adolescents, pregnant women, lactating women, and the elderly all have special nutrient needs.

• Gender: There are certain differences in nutrient needs between men and women. For example, men generally need more energy, while women need more iron.

• Physiological state: The physiological state of the human body affects the demand for nutrients. For example, the nutrient needs of pregnant and lactating women will increase.

• Disease: Disease can affect the digestive and absorptive functions of the human body, thereby affecting the utilization of nutrients.

• Lifestyle: Unhealthy lifestyles, such as smoking, drinking alcohol, and sitting for a long time, can affect the intake and utilization of nutrients.