Introduction and Definition of Terms

Learning Outcomes

By the end of this chapter, students will be able to:

• Define all key terms related to nutrition and dietetics
• Differentiate between types of diets and nutrients
• Explain processes involved in food utilization

1.1 Lesson Notes — Definition of Terms

Nutrition

Nutrition is the science of food and the nutrients and other substances it contains, their actions, interactions, and balance in relation to health and disease. It also encompasses the processes by which the body ingests, digests, absorbs, transports, utilizes, metabolizes, stores, and excretes food substances to support growth, development, and overall health.

Nutrition also examines the entire food system, including how food is produced, consumed, utilized, stored, and handled after harvesting (post-harvest handling), as these factors influence food availability, quality, safety, and nutritional value.

Nutrition is the science of nourishing the body by consuming and utilizing food to maintain health, promote growth and development, prevent disease, and support normal body functions.

Components of Nutrition

Nutrition encompasses several key components throughout the food system:

a) Food Production

Food production refers to the processes involved in producing food for human consumption. Factors influencing food production include:

• Access to land
• Availability of agricultural inputs (e.g., seeds, fertilizers)
• Climate and weather conditions
• Labour availability
• Agricultural technologies

b) Food Consumption

Food consumption refers to the intake of food by individuals or populations. Nutrition professionals assess food consumption using various dietary assessment methods, including:

• 24-hour dietary recall
• Food Frequency Questionnaire (FFQ)
• Dietary history
• Food records

c) Food Utilization

Food utilization is the process by which nutrients are digested, absorbed, metabolized, and used by the body for:

• Energy production
• Growth and development
• Tissue repair
• Regulation of body functions
• Maintenance of health

d) Food Storage

Food storage involves preserving food under appropriate conditions to maintain its quality, safety, and nutritional value. Proper storage facilities help prevent spoilage, contamination, and nutrient losses.

e) Post-Harvest Handling

Post-harvest handling refers to the activities carried out after harvesting to preserve food quality and reduce losses. These include:

• Cleaning
• Sorting and grading
• Drying (e.g., solar drying)
• Processing
• Packaging
• Transportation
• Storage

Health (Wellness)

According to the World Health Organization (WHO), health is a state of complete physical, mental, social, and psychological well-being, and not merely the absence of disease or infirmity.

Health is a dynamic state that enables individuals to live productive and fulfilling lives. Health comprises several interrelated dimensions:

• Physical well-being – proper functioning of the body and freedom from illness.
• Mental well-being – the ability to think clearly, cope with stress, and make informed decisions.
• Social well-being – the ability to establish and maintain healthy relationships and interact effectively within society.
• Psychological well-being – emotional stability, self-esteem, resilience, and the ability to manage emotions.

Dietetics

Dietetics is the science and art of applying the principles of nutrition to the planning, preparation, modification, and service of meals for individuals or groups under different conditions of health and disease.

It involves using scientific knowledge of food and nutrition to promote health, prevent disease, and provide nutrition therapy, while considering economic, cultural, social, and psychological factors that influence food choices and eating behaviours.

The practice of dietetics includes:

• Assessment of nutritional needs
• Planning balanced and therapeutic diets
• Preparation and service of meals
• Nutrition counselling and education
• Medical nutrition therapy for disease management
• Monitoring and evaluation of nutritional interventions

Diet

Sum total of food or meals consumed. Diet is also a special course of food to which a person restricts themselves for medical or other reasons. Diet can be used to assess the nutrition status of a person.

There are two types of diets:

• Normal diet – supplies all the nutritional needs of a normal healthy individual with due consideration for age, sex, activity, and physiological needs.
• Therapeutic diet – a diet that is manipulated or modified to suit a certain disease condition, e.g. low carbohydrate diet, sodium-free diet, high protein diet, low fat diet.

Food

Any nutritious substance that people or animals eat or drink, or that plants absorb, in order to maintain life and growth. Food serves 3 main functions: physiological, social, and psychological.

Meal

A meal is any single food or collection of foods that you eat and consider to be a specific event (breakfast, brunch, lunch, afternoon tea, tea, dinner, supper, etc.). A "dish" is usually made up of several different foods (cooked or not) and might be just one part of a bigger meal.

Components of Food

a) Non-Nutrient Materials

Non-nutrient materials are substances naturally present in food that do not provide nutrients or energy but play important roles in promoting health and improving food quality. Examples include:

• Water
• Natural colours (pigments)
• Natural flavours
• Phytochemicals (e.g., flavanols, flavonoids, and alkaloids)
• Polyphenols (e.g., tannins)
• Indigestible plant materials that contribute to dietary fibre

Although these substances have little or no direct nutritive value, many possess health-promoting properties such as antioxidant, anti-inflammatory, and disease-protective effects. Information regarding their health benefits should be communicated accurately to consumers through scientifically supported nutrition and health claims. Appropriate legislation and regulatory frameworks are necessary to protect consumers from misleading claims and the misuse of these substances in food marketing.

b) Antinutrients

Antinutrients are naturally occurring compounds in foods that interfere with the digestion, absorption, or utilization of nutrients in the body. They may reduce the bioavailability of certain nutrients, particularly minerals and proteins. Common antinutrients include:

• Anti-enzymes (e.g., avidin)
• Trypsin inhibitors (anti-trypsin)
• Phytates
• Oxalates (which bind minerals such as calcium, iron, and zinc)
• Tannins

Many antinutrients can be reduced through food processing methods such as soaking, fermentation, germination, and cooking.

c) Toxic Constituents

Toxic constituents are naturally occurring or contaminating substances in foods that may cause illness or even death when consumed in excessive amounts. Examples include:

• Dhurrin found in sorghum and millet
• Mycotoxins produced by moulds and fungi
• Cyanide and hydrogen cyanide
• Solanine found in green or sprouted potatoes
• Heavy metals such as mercury, lead, and arsenic
• Radioactive substances

Proper food production, processing, storage, and preparation practices help minimize exposure to these toxic substances and reduce their adverse health effects.

Note: To obtain nutrients from food, the body undergoes several physiological processes: ingestion, digestion, absorption, assimilation, metabolism, and excretion of waste products.

d) Nutrients

Nutrients are chemical substances obtained from food that are required by the body to provide energy, support growth and development, maintain and repair body tissues, and regulate various physiological processes.

The six major classes of nutrients are: Carbohydrates, Proteins, Lipids (Fats), Vitamins, Minerals, and Water.

Nutrients are classified into macronutrients and micronutrients according to the quantities required by the body.

i) Macronutrients

Macronutrients are nutrients needed in the body in large amounts, and they include carbohydrates, proteins, and lipids. They form the bulk of the diet and should supply all the energy needed in the food.

• Carbohydrates are organic molecules with a basic ratio of 1C:2H:1O, found as monomers and polymers.
• Protein is an organic polymer made of amino acid subunits, further divided into:
  • Complete protein: contains all essential amino acids
  • Incomplete protein: is missing one or two essential amino acids
• Fats — total fat is the summation of saturated and unsaturated fats in a food.
  • Unsaturated fats are lipids that are liquid at room temperature and contain double bonds between carbons.
  • Saturated fats are lipids that are solid at room temperature and contain single bonds between carbons.
  • Cholesterol is a lipid with a ringed molecular structure that is carried in the blood as HDL & LDL particles.

ii) Micronutrients

Micronutrients are nutrients needed in our bodies in small amounts. They include vitamins and minerals.

• Vitamins are organic compounds required in tiny amounts by an organism for normal growth and development, used as co-factors for enzymes, and as hormones and antioxidants. Divided into fat-soluble vitamins and water-soluble vitamins.
• Minerals are chemical elements required by living organisms, divided into microelements and macroelements.
• Fibre – the indigestible portion of plants (mainly composed of cellulose), commonly called "roughage." Classified into:
  • Soluble fibre, which absorbs water, turning into a gel-like mush (like oatmeal with water)
  • Insoluble fibre, which does not absorb water (like celery with water)

Key Terms Glossary

• Serving – the amount of a product normally eaten in one sitting (sizes based on cups, tsp, tbsp).
• Calorie – the amount of heat (energy) required to raise the temperature of one gram of water by 1°C; measures a food's total energy available for use in the body.
• Hydrogenated vegetable oil – liquid vegetable oils processed by adding hydrogen to create solid or semi-solid fats, such as those in margarine.
• Essential nutrients – nutrients that must be obtained from food because they cannot be synthesized in the body in adequate amounts to meet the body's physiological needs.
• Malnutrition – any condition caused by an excess or deficiency of energy or nutrient intake, or an imbalance between dietary intake and requirement.
• Good/normal/optimal nutrition – a sufficiency of nutrient intake that maintains normal growth and development, optimum activity, resistance to infection, and ability to repair the body after injury.
• Nutritional status – the condition of health of an individual as influenced by the intake and utilization of nutrients.
• Nutritional deficiency – a condition of the body that may arise as a result of lack of one or more nutrients in the diet, or breakdown of one or more of the bodily processes concerned with nutrient utilization.
• Nutrition screening – the process of identifying clinical characteristics known to be associated with malnutrition, in order to identify persons at risk and plan appropriate nutrition therapy.
• Nutrition assessment – the comprehensive analysis of a person's nutrition status using health, socioeconomic, drug, and diet histories; anthropometric measurements; physical examinations; and laboratory tests.