Introduction, careers, nutrients in depth, digestion, absorption, metabolism, composition tables and food tests

Foods and Nutrition is the study of food: what it contains, how the body uses it, how it is chosen, bought, stored, prepared, preserved and served, and how these choices affect health, family life and business. It is a branch of Home Economics but it is examined by WAEC and NECO as a separate subject with three papers: an objective paper, an essay paper and a three-hour practical conducted by a visiting examiner. The practical is worth as much as the other two papers combined, so every lesson in this course links theory to what you will actually cook, plan and present.

Basic definitions you must state accurately

• Food: any solid or liquid which, when eaten, digested and absorbed, provides the body with energy, materials for growth and repair, and substances that regulate body processes and protect against disease.
• Nutrition: the science of food and how the body takes it in and uses it, from ingestion through digestion, absorption, transport, metabolism and excretion of waste.
• Nutrients: the chemical substances in food that do the work: carbohydrates, proteins, fats and oils, vitamins, minerals and water. Dietary fibre is usually listed alongside them.
• Nutritive value: the amount and quality of nutrients a food supplies. Egg has high nutritive value for protein; sugar has energy but almost nothing else, so it is said to supply empty calories.
• Diet: the foods a person habitually eats. A special diet or therapeutic diet is one adjusted for a medical condition.
• Dietetics: the application of nutrition science to the feeding of individuals and groups in health and disease. A dietitian is the professional who does this.

Importance of human nutrition

1. Growth and development. Children who are well fed grow to their potential in height, brain development and learning. Stunting in early childhood is largely irreversible after about two years of age.
2. Health and resistance to disease. Good nutrition strengthens immunity; malnourished children suffer more severe measles, diarrhoea and pneumonia.
3. Energy for work and study. A student who skips breakfast concentrates poorly by mid-morning.
4. Prevention of deficiency diseases such as kwashiorkor, rickets, anaemia, goitre and night blindness.
5. Prevention of diet-related chronic diseases: obesity, type 2 diabetes, hypertension, heart disease and some cancers are rising in Nigerian cities.
6. Productivity and national development. A well-nourished population works longer and earns more; malnutrition costs the economy through illness and lost schooling.
7. Healthy pregnancy and childbirth, reducing low birth weight and maternal anaemia.

The study and the exam

Questions on this opening topic usually ask you to define terms, give reasons why nutrition is important, or list factors affecting food choice. Always give a short definition followed by a Nigerian example: examiners reward application. For instance, “a food with high nutritive value for protein, such as boiled egg or fried fish” is stronger than the bare definition.