Chapter 3 of 8

All 8 chapters
  1. 1Organs and systems, readunderstood
  2. 2Digestion, readunderstood
  3. 3Nutrients and diet, readunderstood
  4. 4Breathing, readunderstood
  5. 5Gas exchange in the lungs, readunderstood
  6. 6The heart and blood, readunderstood
  7. 7Pulse, breathing and exercise, readunderstood
  8. 8Drugs, alcohol and health, readunderstood

S3.3.3 Chapter 3

Nutrients and diet

Why do I need different kinds of food, and what happens if I miss one?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

  • Explain what carbohydrates, proteins, fats, vitamins, minerals and fibre do
  • Name a disease caused by too little of a vitamin or mineral

Food is more than something that fills your belly. It holds nutrients, the parts of food that your body uses. Build the picture of what each one does.

Draw it first

Draw what each nutrient does

  1. A table with two columns, nutrient and job, built in three steps. The first step lists carbohydrate for energy, protein for growth and repair, and fat for store energy. The second adds vitamins to keep you well and minerals for many jobs. The third adds fibre to move food on and water to carry things. Labels: nutrient, job, carbohydrate, energy, protein, growth, repair, fat, store energy, vitamins, keep you well, minerals, strong bones, fibre, moves food on, water, carries things.nutrientjobcarbohydrateenergyproteingrowth, repairfatstore energy

    1 Write three nutrients, and one job for each: carbohydrate, protein and fat.

  2. A table with two columns, nutrient and job, built in three steps. The first step lists carbohydrate for energy, protein for growth and repair, and fat for store energy. The second adds vitamins to keep you well and minerals for many jobs. The third adds fibre to move food on and water to carry things. Labels: nutrient, job, carbohydrate, energy, protein, growth, repair, fat, store energy, vitamins, keep you well, minerals, strong bones, fibre, moves food on, water, carries things.nutrientjobcarbohydrateenergyproteingrowth, repairfatstore energyvitaminskeep you wellmineralsmany jobs

    2 Add vitamins and minerals. They keep your body working.

  3. A table with two columns, nutrient and job, built in three steps. The first step lists carbohydrate for energy, protein for growth and repair, and fat for store energy. The second adds vitamins to keep you well and minerals for many jobs. The third adds fibre to move food on and water to carry things. Labels: nutrient, job, carbohydrate, energy, protein, growth, repair, fat, store energy, vitamins, keep you well, minerals, strong bones, fibre, moves food on, water, carries things.nutrientjobcarbohydrateenergyproteingrowth, repairfatstore energyvitaminskeep you wellmineralsmany jobsfibremoves food onwatercarries things

    3 Add fibre, and water too. Your body needs both.

Carbohydrates give you energy. Rice, bread, maize and cassava are full of them. Your muscles and brain use this energy all day.

Proteins build your body and mend it when it is hurt. Beans, fish, eggs, nuts and meat have a lot of protein.

Fats and oils store energy and keep you warm. A little fat gives a lot of energy, so you need only a small amount.

Vitamins and minerals are needed in tiny amounts. They help the body use everything else. Vitamins and minerals give no energy themselves.

Fibre is the part of plants that your body cannot digest. It helps food move through the gut. Vegetables, fruit and whole grains have fibre.

A table with two columns, food and rich in. Rice is rich in carbohydrate, beans in protein, oil in fat, oranges in vitamin C, milk in calcium, and vegetables in fibre. Labels: food, rich in, rice, carbohydrate, beans, protein, oil, fat, oranges, vitamin C, milk, calcium, vegetables, fibre.foodrich inricecarbohydratebeansproteinoilfatorangesvitamin Cmilkcalciumvegetablesfibre
Most foods hold more than one nutrient. This table names the one each food is best known for.
A table with two columns, need and helps. Vitamin C helps gums and skin. Vitamin D helps bones. Calcium helps bones and teeth. Iron helps blood. Iodine helps the thyroid gland. Labels: need, helps, vitamin C, gums and skin, vitamin D, bones, calcium, bones, teeth, iron, blood, iodine, thyroid gland.needhelpsvitamin Cgums and skinvitamin Dbonescalciumbones, teethironbloodiodinethyroid gland
Iron helps the blood carry oxygen. Your skin makes vitamin D when sunlight falls on it. Iodine is used by the thyroid, a gland in the neck. With too little iodine the thyroid grows bigger, and the neck swells.

Too little of a vitamin or a mineral, for a long time, can make a person ill. This is a deficiency disease.

A table with two columns, too little and disease. Too little vitamin C gives scurvy. Too little vitamin D gives rickets. Too little calcium gives rickets. Too little iron gives anaemia. Too little iodine gives goitre. Labels: too little, disease, vitamin C, scurvy, vitamin D, rickets, calcium, rickets, iron, anaemia, iodine, goitre.too littlediseasevitamin Cscurvyvitamin Dricketscalciumricketsironanaemiaiodinegoitre
Each of these diseases has a cause you can name.

Scurvy makes the gums sore and bleed, and cuts heal slowly. Rickets makes the bones of a child soft, so the legs can bend.

A standing skeleton seen from the front, with two parts named. Strong leg bones and hip bones hold the body up. Labels: leg bones, hip.leg boneship
Leg bones hold your weight. They need vitamin D and calcium to grow hard. Without them the bones stay soft and can bend.

Anaemia makes a person pale and tired, because the blood carries too little oxygen. Goitre makes the neck swell.

A mixed diet helps to prevent them. Sunlight on the skin gives vitamin D. Where food has too little iodine, salt with iodine added prevents goitre. Anaemia has other causes too. A health worker can test and advise.

See it three ways

With things

Write down everything you ate yesterday. Put each food under energy or growth. Some foods belong in both.

As a picture

Two overlapping circles. The left circle is labelled energy and holds rice and oil. The right circle is labelled growth and holds fish. Where they overlap are peas, milk and eggs. Labels: energy, growth, rice, oil, fish, peas, milk, eggs.energygrowthriceoilpeasmilkeggsfish

In words

Carbohydrates and fats give energy. Proteins help you grow and mend. Peas, milk and eggs hold both kinds, so they sit in the middle.

Try it

Find the fat

You need: 3 pieces of plain paper, a few drops of cooking oil, water, a slice of raw potato.

Be safe: Do not eat the potato or taste the oil. Wash your hands after you have touched them.

  1. Put a drop of oil on one piece of paper. Put a drop of water on the second. Rub the cut face of the potato on the third.
  2. Leave all three for an hour in a warm place. Hold each one up to the light.
  3. Look for a mark that lets the light through and does not go away.

What you will see: The oil leaves a clear greasy mark. The water dries away. The potato leaves a damp mark that dries away. Fat leaves a clear mark that stays.

If you cannot try it, this is what happens.
A table with two columns, on paper and later. Oil leaves a clear mark. Water dries away. Raw potato leaves a damp mark that dries away. Labels: on paper, later, oil, clear mark, water, dries away, raw potato, dries away.on paperlateroilclear markwaterdries awayraw potatodries away

A wrong idea many people have

Vitamins give you energy.

Why it feels right: People who feel tired are often told to take vitamins.

The test that breaks it: Energy comes from carbohydrates and fats. A person who eats vitamins but no rice, bread or oil would still run out of energy.

What is true: Carbohydrates and fats give energy. Vitamins and minerals help your body work, and they give no energy.

Key words

nutrients
the parts of food that the body uses.
carbohydrates
nutrients that give energy, such as the starch in rice and bread.
proteins
nutrients that build the body and mend it.
vitamins
nutrients needed in tiny amounts to keep the body working.
minerals
nutrients such as iron and calcium, needed in small amounts.
fibre
the part of plants that helps food move through the gut.

Back to your guess

The answer is B: Each kind of food does its own job, so the body needs a mix.

Each nutrient has its own job. The body needs a mix of them, and too little of one can make a person ill.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Which nutrients are needed in tiny amounts, to keep the body working?

    Tap your answer.

    1. Not this one. Fats store energy and keep you warm. Their job is different from the job of vitamins and minerals. Go to S3.3.3. Try another.

    2. Yes, that is right. Vitamins and minerals are needed in tiny amounts. They help the body use everything else.

    3. Not this one. Fibre helps food move through the gut. It is not one of the tiny-amount nutrients. Go to S3.3.3. Try another.

    See the answer

    Vitamins and minerals

    Vitamins and minerals are needed in tiny amounts. They help the body use everything else.

    • If you chose A: Fats store energy and keep you warm. Their job is different from the job of vitamins and minerals. Go to S3.3.3.
    • If you chose C: Fibre helps food move through the gut. It is not one of the tiny-amount nutrients. Go to S3.3.3.

  2. Which nutrient helps your body grow and mend?

    Tap your answer.

    1. Yes, that is right. Proteins are the building nutrient. Beans, fish and eggs have a lot of them.

    2. Not this one. Carbohydrates give energy. Protein is the nutrient that builds and mends. Go to S3.3.3. Try another.

    3. Not this one. Fibre helps food move through the gut. It does not build the body. Go to S3.3.3. Try another.

    See the answer

    Protein

    Proteins are the building nutrient. Beans, fish and eggs have a lot of them.

    • If you chose B: Carbohydrates give energy. Protein is the nutrient that builds and mends. Go to S3.3.3.
    • If you chose C: Fibre helps food move through the gut. It does not build the body. Go to S3.3.3.

  3. What does fibre do?

    Tap your answer.

    1. Not this one. Your body cannot digest fibre, so it gives no energy. Carbohydrates and fats do. Go to S3.3.3. Try another.

    2. Not this one. Protein builds muscle. Fibre has a different job. Go to S3.3.3. Try another.

    3. Yes, that is right. Fibre is the part of plants that cannot be digested. It stays in the gut and helps push the food along.

    See the answer

    It helps food move through the gut

    Fibre is the part of plants that cannot be digested. It stays in the gut and helps push the food along.

    • If you chose A: Your body cannot digest fibre, so it gives no energy. Carbohydrates and fats do. Go to S3.3.3.
    • If you chose B: Protein builds muscle. Fibre has a different job. Go to S3.3.3.

  4. Which pair of nutrients gives your body energy?

    Tap your answer.

    1. Not this one. Vitamins and minerals help the body work, but they give no energy themselves. Go to S3.3.3. Try another.

    2. Not this one. Neither fibre nor water gives energy. Your body cannot get energy from them. Go to S3.3.3. Try another.

    3. Yes, that is right. Carbohydrates and fats are the energy nutrients. Rice and oil are good sources.

    See the answer

    Carbohydrates and fats

    Carbohydrates and fats are the energy nutrients. Rice and oil are good sources.

    • If you chose A: Vitamins and minerals help the body work, but they give no energy themselves. Go to S3.3.3.
    • If you chose B: Neither fibre nor water gives energy. Your body cannot get energy from them. Go to S3.3.3.

  5. A child who gets too little vitamin D or calcium can have soft, bent bones. What is this disease called?

    Tap your answer.

    1. Not this one. Scurvy comes from too little vitamin C, and it makes the gums sore. Go to S3.3.3. Try another.

    2. Yes, that is right. Bones need vitamin D and calcium to grow hard. Without enough of them they stay soft and can bend.

    3. Not this one. Goitre comes from too little iodine, and it makes the neck swell. Go to S3.3.3. Try another.

    See the answer

    Rickets

    Bones need vitamin D and calcium to grow hard. Without enough of them they stay soft and can bend.

    • If you chose A: Scurvy comes from too little vitamin C, and it makes the gums sore. Go to S3.3.3.
    • If you chose C: Goitre comes from too little iodine, and it makes the neck swell. Go to S3.3.3.

  6. A girl is pale and tired. Her blood carries too little oxygen, because she gets too little iron. What is this called?

    Tap your answer.

    1. Yes, that is right. Iron helps the blood carry oxygen. Too little iron gives anaemia, and the person feels pale and tired.

    2. Not this one. Scurvy is the disease of too little vitamin C. The pale, tired blood in this case is from too little iron. Go to S3.3.3. Try another.

    3. Not this one. Rickets is the disease of soft bones. It comes from too little vitamin D or calcium. Go to S3.3.3. Try another.

    See the answer

    Anaemia

    Iron helps the blood carry oxygen. Too little iron gives anaemia, and the person feels pale and tired.

    • If you chose B: Scurvy is the disease of too little vitamin C. The pale, tired blood in this case is from too little iron. Go to S3.3.3.
    • If you chose C: Rickets is the disease of soft bones. It comes from too little vitamin D or calcium. Go to S3.3.3.

  7. From an earlier chapter

    Which part of the gut takes back water from what is left of the food?

    Tap your answer.

    1. Not this one. The gullet only squeezes food down to the stomach. Go to S3.3.2. Try another.

    2. Not this one. The stomach mixes and squeezes the food. It does not take back water. Go to S3.3.2. Try another.

    3. Yes, that is right. The large intestine takes water back into the body. What is left leaves as waste.

    See the answer

    The large intestine

    The large intestine takes water back into the body. What is left leaves as waste.

    • If you chose A: The gullet only squeezes food down to the stomach. Go to S3.3.2.
    • If you chose B: The stomach mixes and squeezes the food. It does not take back water. Go to S3.3.2.

Keep it

Copy this into your exercise book.

Carbohydrates and fats give energy. Proteins build and mend. Vitamins and minerals help the body work. Fibre moves food on. Too little iron, iodine or a vitamin can cause disease.

Draw: Draw a table of six nutrients, with one job and one food beside each.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

No internet tomorrow? Save the whole book as one file (799 KB). It opens on any phone.