What are the main types of nutrients essential for human health?

The main types of nutrients essential for human health include carbohydrates, proteins, fats, vitamins, minerals, and water. Each of these nutrients plays a crucial role in maintaining bodily functions, supporting growth, and providing energy. In the IB MYP Science curriculum, understanding these nutrients helps students learn about how systems in organisms work together to sustain life.

How do carbohydrates function in the body?

Carbohydrates are the body's primary source of energy. They are broken down into glucose, which is used by cells for energy. In the context of the IB MYP Science curriculum, students explore how carbohydrates are metabolized and their role in energy production, which is vital for understanding how organisms maintain their systems and perform daily activities.

Why are proteins important for growth and repair in organisms?

Proteins are essential for growth and repair because they are made up of amino acids, which are the building blocks of cells and tissues. They play a critical role in building muscle, repairing tissues, and producing enzymes and hormones. In the IB MYP Science framework, students learn about the significance of proteins in maintaining the structural and functional integrity of organisms.

What role do vitamins and minerals play in maintaining health?

Vitamins and minerals are crucial for maintaining health as they support various bodily functions, including immune response, bone health, and energy production. Vitamins such as A, C, and D, along with minerals like calcium and iron, are vital for the proper functioning of systems in organisms. The IB MYP curriculum emphasizes understanding these nutrients to appreciate their role in sustaining life processes.

How does water contribute to the functioning of systems in organisms?

Water is vital for all living organisms as it facilitates numerous bodily functions, including digestion, nutrient transport, temperature regulation, and waste elimination. It acts as a solvent for biochemical reactions and helps maintain homeostasis. In the IB MYP Science curriculum, students study the importance of water in supporting the systems in organisms, highlighting its role in sustaining life.

Why is "Forgetting fibre and water." a common mistake in Nutrients?

Why it happens: They're not 'energy' nutrients. How to avoid it: There are SEVEN groups, not five. Fibre prevents constipation and bowel cancer; water is the body's main solvent.

Why is "Forgetting to heat Benedict's solution." a common mistake in Nutrients?

Why it happens: Test feels like 'just add a chemical'. How to avoid it: Benedict's requires HEATING in a water bath. Without heat, no colour change. Iodine and biuret DON'T need heating.

Systems in OrganismsIB MYP Sciences (Years 1-5)

Nutrients

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Nutrients — IB MYP Sciences: the seven things your body needs from food

A balanced diet contains the right amounts of seven groups: carbohydrate, protein, fat, vitamins, minerals, fibre and water. This MYP Sciences note covers each and what happens if you miss them.

What you’ll learn

Mapped to the IB MYP Sciences subject guide (2026 onwards).

MYP Sciences A — Name the seven nutrients and their roles.
MYP Sciences A — Identify food tests for starch, sugar, protein, fat.
MYP Sciences C — Read a food label and judge a balanced diet.
MYP Sciences D — Discuss deficiency diseases (scurvy, rickets, kwashiorkor).

The seven food groups

Energy, building blocks, micronutrients, fibre, water.

1. Carbohydrate (~50% of diet by energy). Body's main fuel.

Simple sugars (glucose, fructose): quick energy.
Complex carbs (starch in potato/bread/rice): slower release.
Sources: bread, rice, pasta, potatoes, fruit.

2. Protein (~15-20%). For growth, repair, enzymes, hormones.

Made of amino acids; you need ~9 essential ones from food.
Sources: meat, fish, eggs, dairy, beans, tofu, nuts.

3. Fat (~30%). Energy storage, insulation, hormones, vitamin transport.

Unsaturated fats (olive oil, fish, nuts) are healthier.
Saturated and trans fats raise heart-disease risk.

4. Vitamins. Needed in tiny amounts; chemicals the body can't make.

Vitamin A (carrots): vision.
Vitamin C (citrus): immune function. Deficiency → scurvy.
Vitamin D (sun): bone strength. Deficiency → rickets.
B vitamins (whole grains): energy metabolism.

5. Minerals. Inorganic elements.

Calcium (milk): bones, teeth.
Iron (red meat): haemoglobin. Deficiency → anaemia.
Iodine (seafood, salt): thyroid hormone. Deficiency → goitre.

6. Fibre (whole grains, vegetables, fruit). Cellulose — not digestible. Keeps food moving through intestine; prevents constipation; lowers cancer risk.

7. Water. Solvent for ALL chemical reactions in the body. Need ~2-2.5 L/day.

C (carbs), P (protein), F (fat) — major nutrients.
Vitamins + minerals — tiny amounts but essential.
Fibre + water — often forgotten but vital.

Food tests

Four key chemical tests with a colour change for each.

Standard lab tests in MYP:

Substance	Test	Positive result
Starch	Iodine solution	Brown → blue-black
Reducing sugar (glucose, fructose)	Benedict's solution + heat	Blue → orange/brick-red precipitate
Protein	Biuret reagent (NaOH + CuSO₄)	Blue → purple/lilac
Fat	Rub on filter paper	Translucent grease spot. Alternative: ethanol + water emulsion turns cloudy white

These tests are widely featured in MYP criterion-B investigations: 'Plan an experiment to identify the nutrients in an unknown food'. The standard process:

Crush the food sample, add water, filter.
Split the liquid into 4 portions.
Run each test (iodine, Benedict's + heat, biuret, ethanol).
Note the colour changes.

Starch: iodine → blue-black.
Sugar: Benedict's + heat → brick-red.
Protein: biuret → purple.
Fat: grease spot on paper OR ethanol cloudiness.

Deficiency diseases

What happens if a nutrient is missing?

Each nutrient missing → specific disease:

Missing nutrient	Disease	Symptoms
Vitamin C	Scurvy	Bleeding gums, slow wound healing, weakness
Vitamin D	Rickets	Soft, bent bones (especially in children)
Iron	Anaemia	Tiredness, pale skin, breathlessness
Iodine	Goitre	Swollen thyroid, weight gain, fatigue
Protein	Kwashiorkor	Swollen belly, stunted growth, wasted muscle
Calories	Marasmus	Severe wasting from total lack of food

Some of these are now rare in developed countries but were common in the past. Famous case: in the 18th century sailors developed scurvy on long voyages. James Lind discovered (1747) that citrus fruits prevented it — eventually leading to lemon juice being given to British sailors ('Limeys'). Vitamin C wasn't isolated until 1932.

Modern issues:

Iron deficiency is the most common nutritional deficiency worldwide.
Vitamin D deficiency is common in cloudy northern countries and during winter.
Obesity (over-nutrition) is now bigger than undernutrition in many countries.

Scurvy (vit C), rickets (vit D), anaemia (iron).
Kwashiorkor (protein-energy), marasmus (severe starvation).
Modern: iron and vit D deficiencies still common.

How it’s examined

Criterion A: name groups and tests. Criterion B: plan a food-test investigation. Criterion D: discuss deficiency diseases or modern over/undernutrition.

Sources: IB MYP Sciences guide (IBO, official subject guide). Last reviewed 2026-05-25.

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Step-by-step worked examples — Nutrients

Step-by-step solutions to past-paper-style questions on nutrients, written exactly the way a tutor would explain them at the board.

1Identify the nutrient from a colour change
Getting started• food tests
Question
A student adds Benedict's solution to a food sample, heats it, and the solution turns brick-red. What does this show?
Step-by-step solution
1. Step 1
  Benedict's test detects REDUCING SUGARS (glucose, fructose, maltose).
2. Step 2
  Brick-red precipitate = positive result → the food contains a reducing sugar.
Answer
Reducing sugar present (e.g. glucose).
2Scurvy and limes
Building confidence• deficiency
Question
Why did 18th-century sailors on long voyages often get scurvy, and how did giving them limes help?
Step-by-step solution
1. Step 1
  Long voyages → no fresh fruit or vegetables → no vitamin C intake.
2. Step 2
  Without vitamin C, the body can't make collagen → SCURVY (bleeding gums, slow healing, weakness).
3. Step 3
  Limes contain vitamin C. Daily lime juice restored vitamin C and prevented scurvy. (This is why British sailors became known as 'Limeys'.)
Answer
No vit C on long voyages → scurvy. Limes contain vit C → daily lime juice prevented scurvy.
3Plan a balanced lunch
Stretch• balanced diet
Question
Design a balanced lunch that includes all seven nutrient groups. List each component and which nutrient it provides.
Step-by-step solution
1. Step 1
  Wholegrain bread sandwich: bread = CARBOHYDRATE + FIBRE.
2. Step 2
  Chicken or tofu filling: PROTEIN.
3. Step 3
  Salad (lettuce, tomato, carrot): VITAMINS, MINERALS, FIBRE.
4. Step 4
  Olive oil dressing or avocado slices: FAT.
5. Step 5
  Yoghurt + fruit: extra protein and CALCIUM, more vitamins.
6. Step 6
  Water to drink: WATER.
Answer
Wholegrain sandwich (carbs+fibre) + chicken/tofu (protein) + salad (vits/mins/fibre) + olive oil (fat) + yoghurt (mins) + water.

Key Definitions and Keywords — Nutrients

Definitions to memorise and the exact keywords mark schemes credit for nutrients answers — sharpened from recent examiner reports for the 2026 IB MYP Sciences sitting.

Balanced diet
Examiner keyword
A diet that supplies the right amount of all seven food groups for the person's needs.
Carbohydrate
Examiner keyword
An energy nutrient including sugars and starch.
Protein
Examiner keyword
A nutrient used for growth, repair, and to make enzymes, hormones, antibodies.
Vitamin
Examiner keyword
A chemical needed in small amounts that the body cannot make.
Fibre
Examiner keyword
Indigestible plant material (mostly cellulose) that keeps food moving through the intestine.

Common Mistakes and Misconceptions — Nutrients

The traps other students keep falling into on nutrients questions — taken from recent IB MYP Sciences examiner reports and mark schemes — and how to avoid them.

✕Forgetting fibre and water.
Why it happens
They're not 'energy' nutrients.
How to avoid it
There are SEVEN groups, not five. Fibre prevents constipation and bowel cancer; water is the body's main solvent.
✕Forgetting to heat Benedict's solution.
Why it happens
Test feels like 'just add a chemical'.
How to avoid it
Benedict's requires HEATING in a water bath. Without heat, no colour change. Iodine and biuret DON'T need heating.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

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Nutrients — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Nutrients

Short Study Notes in the form of Slides

Short Study Notes — Nutrients

Detailed Notes

What you’ll learn

How it’s examined

1Identify the nutrient from a colour change

2Scurvy and limes

3Plan a balanced lunch

Balanced diet

Carbohydrate

Protein

Vitamin

Fibre

✕Forgetting fibre and water.

✕Forgetting to heat Benedict's solution.

Practice questions

Past paper style quiz

Assess your understanding

Nutrients — frequently asked questions