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Food and Nutrition

12 min read

Food and nutrition

Food is any substance that is eaten to give the body energy, growth and protection from disease. Nutrition is the study of how the body uses food. A nutrient is a substance in food that the body needs. The main nutrients are carbohydrates, proteins, fats and oils, vitamins, minerals and water; dietary fibre also helps. Good nutrition keeps people healthy, strong and productive.

Food groups

GroupMain nutrientExamplesJob
Energy-giving (staples)Carbohydrates, fatsMaize, rice, cassava, bananas, potatoes, oilsProvide energy
Body-buildingProteinsBeans, fish, meat, eggs, milk, groundnutsGrowth and repair
ProtectiveVitamins and mineralsFruits and vegetables, liver, milkFight disease, keep body working
Water and fibreWater, roughageWater, whole grains, vegetablesDigestion and transport
A balanced plateA plate split into food groups. About a third is energy-giving foods (cereals, roots and tubers), about a third is vegetables and fruits that protect the body, about a quarter is body-building foods (beans, fish, meat, eggs and milk), and a little is fat and sugar, with plenty of water to drink.energyprotectbuildfatcereals, roots, tubers (energy)fruits and vegetables (vitamins, minerals)beans, fish, meat, eggs, milk (protein)oil, sugar (small amounts)

Nutrients and their foods

NutrientSourceFunctionLack causes
CarbohydrateCereals, roots, sugarEnergy (17 kJ per g)Weakness
ProteinBeans, meat, fish, eggsGrowth, repair (17 kJ per g)Kwashiorkor
FatOils, butter, groundnutsEnergy store (37 kJ per g), warmthPoor weight
Vitamin AOrange fruits, liver, green vegetablesSight, skinNight blindness
Vitamin CCitrus, guava, tomatoWound healing, gumsScurvy
IronLiver, beans, green vegetablesHaemoglobinAnaemia
CalciumMilk, small fish with bonesBones and teethRickets
IodineIodised salt, sea fishThyroidGoitre

A balanced meal

A balanced meal has foods from every group in the right amounts, with enough variety, colour and water. For example: ugali (energy), beans or fish (body-building), and spinach with tomatoes and an orange (protective).

Fat gives more than twice as much energy as carbohydrate or protein.
Try itEnergy in a meal

Choose the grams of carbohydrate, protein and fat in a meal.

Check yourself Which nutrient gives the most energy per gram?
Check yourself Beans are mainly a
Check yourself Lack of iodine causes

Key terms

Nutrient
A substance in food that the body needs.
Balanced meal
A meal with all the food groups in good amounts.
Staple
The main energy food in a diet.
Deficiency
A lack of a nutrient.

Summary

  • The main nutrients are carbohydrates, proteins, fats, vitamins, minerals and water.
  • Foods are energy-giving, body-building or protective.
  • A balanced meal has all the food groups.
  • Energy: carbohydrate and protein 17 kJ/g, fat 37 kJ/g.
Hygiene and Safety in the Kitchen