Resource 5: Data on food and energy

Teacher resource for planning or adapting to use with pupils

Food

A healthy diet requires adequate amounts of protein, carbohydrate, fat, vitamins, minerals and water.

A rough guide to daily requirements is as follows:

  • protein 50 g
  • carbohydrate 300 g
  • fat 65 g
  • fibre 30 g  
  • vitamin A 730 μg
  • vitamin C 60 mg
  • iron 11 mg (males), 15 mg (females)
  • calcium 1300 mg.

Note the different units for different nutrients:

1 mg = 1/1000 g                      1 μg = 1/1000 mg.

Sources of the main nutrients

FoodRich source ofModerate source of
CerealsStarch, fibreProtein, B vitamins, many minerals
Starchy roots and fruits (yams, maize, cassava, potatoes, rice)Starch, fibreSome minerals, vitamin C if fresh, vitamin A if yellow or orange
Beans and peasProtein, starch, some minerals, fibreB vitamins
OilseedsFat, protein, fibreB vitamins, some minerals
Fats and oilsFatVitamin A if orange or red
Dark to medium-green leavesVitamins A and C, folateProtein, minerals
Orange vegetablesVitamins A and CFibre
Orange fruitsVitamins A and CFibre
Citrus fruitsVitamin CFibre
MilkFat, protein, calcium, vitamins 
EggsProtein, vitaminsFat, minerals (not iron)
MeatProtein, fat, iron 
FishProtein, iron 
LiverProtein, iron, vitamins 

Sources of vitamins

VitaminGood sources
Vitamin ALiver, fish liver oils, egg yolk, milk and dairy products, green leafy vegetables (especially kale, amaranth, sweet potato, cowpea and cassava leaves), yellow and orange-coloured fruits and vegetables (carrots, pumpkin, mango, papaya, oranges), orange-coloured sweet potato, palm oil
Vitamin DCod-liver oil, oily fish, liver, egg yolk
Vitamin EVegetable oils (such as maize, soybean and sunflower oils), nuts, soybeans, cereals, egg yolk
Vitamin KGreen leafy vegetables, vegetable oils, egg yolk, beef, mutton, poultry
Thiamine (vitamin B1)Millets, sorghum, wheat, maize, dried beans, rice, liver, kidney, beet, nuts
Riboflavin (vitamin B2)Green leafy vegetables, liver, kidney, milk, cheese, eggs, whole grains
Niacin (nicotinic acid and nicotinamide)Lean meat, poultry, fish, groundnuts, dried beans, wheat, yam, potato
Pantothenic acidKidney, fish, egg yolk, most vegetables, most cereals
Pyridoxine (vitamin B6)Meat, poultry, fish, egg yolk, whole grains, banana, potato, dried beans, lentils, chickpeas
Biotin (vitamin H)Groundnuts, dried beans, egg yolk, mushrooms, banana, grapefruit, watermelon
Folic acidGreen leafy vegetables (losses from cooking can be high), fresh fruits (especially orange juice), dried beans, peas, nuts, egg yolk, mushrooms, banana, liver
Vitamin B12 (cyanocobalamin)Liver, kidney, chicken, beef, fish, eggs, milk, cheese

Extension activities: food and energy

We need energy to stay alive and carry out our daily activities. This energy comes from the food we eat. Energy is measured in units called joules (J). One joule is quite a small amount of energy, so we usually use kilojoules (kJ) to measure our energy requirements.

  • 1 kilojoule = 1000 joules.

Teenagers should eat enough food to provide them with between 10 000 and 15 000 kJ each day. The exact amount required will vary according to size (mass), age, sex (in general boys need more than girls) and activity.

On average, a teenage girl needs 11 000 kJ of energy each day.

On average, a teenage boy needs 13 000 kJ of energy each day.

Task 1

Plan a diet for a day for a teenage boy or girl. The food you select and the amounts of each food should be enough to meet the energy requirements of an average teenager as given above. Do not forget to include snacks as well as main meals.

Use the information in the table below to help you. You will need to estimate how many grams of each food you will require before you calculate the energy it provides.

Energy content of some common foods

FoodEnergy content in kJ per 100gFoodEnergy content in kJ per 100g
Milk272Rice1504
Eggs662Banana318
Chicken771Melon96
White fish289Orange147
Oily fish796Spinach88
Haricot beans1073Biscuits (sweet, rich)2078
Broad beans289Bread (brown)993
Lentils1236Bread (white)1060
Green peppers88Pasta1525
Potato364Maize meal1350
Cassava667Yams462

You can record your diet plan in a table like the one below.

Energy content of a sample diet for a teenager for one day

MealFood itemAmount of this food in gEnergy content of this food in kJ per 100gTotal energy provided by this food item in your diet

  • Calculate the overall total energy in kJ that your diet will provide.
  • How does this compare with the average requirements for a teenager of your sex?

Diet, energy and activity

Your energy requirements will vary according to your activities. The table below shows the energy requirements for different activities.

Energy requirements for different activities

ActivityEnergy required for each minute by an average teenager in kJActivityEnergy required for each minute by an average teenager in kJ
Sleeping4Sewing12
Watching TV5Digging the garden24
Eating6Swimming30
Washing clothes10Playing football36
Gentle walking12Sprinting60

Task 2

Plan a day where you do various activities for a certain length of time.

A day lasts 24 hours or 1440 minutes.

Activities (and their durations) you might choose could be sleeping, 480 minutes; eating, 50 minutes; swimming, 70 minutes and so on.

Work out how many kilojoules of energy you would need for each activity.

You could record your answer in a table like the one below.

Activities in a day and energy required to perform them

ActivityMinutesEnergy required per minute for this activity in kJTotal energy required for the duration of this activity

  • Calculate the overall total energy in kJ that your activity plan would require.
  • How does this compare with the amount of energy your diet in Task 1 would provide?

Resource 4: Differentiating work

Resource 6: Suggestions for conducting and assessing research