What are the main nutrients studied in N(A)-Level Nutrition and Food Science?

The syllabus groups nutrients into the macronutrients needed in large amounts (protein, carbohydrate and fat), the micronutrients needed in small amounts (vitamins and minerals), plus water and dietary fibre. You must know the functions, food sources and the effects of too little or too much for each, and be able to apply them when judging or planning a diet. Protein and carbohydrate each give about 17 kJ per gram and fat gives about 37 kJ per gram, so fat is the most energy-dense nutrient.

What is the difference between high and low biological value protein?

High biological value (HBV) protein contains all the essential amino acids the body cannot make; these come mainly from animal foods such as meat, fish, eggs and milk, plus the plant foods soya and quinoa. Low biological value (LBV) protein is missing one or more essential amino acids and comes from most plant foods such as beans, lentils, nuts and cereals. By eating two LBV foods together (protein complementation), such as rice and dhal, the amino acids missing from one are supplied by the other.

Which vitamins and minerals does the N(A)-Level syllabus focus on?

The key vitamins are A for eyesight and skin, C for healthy gums and skin and for iron absorption (deficiency causes scurvy), and D for absorbing calcium (deficiency causes rickets). The key minerals are calcium for strong bones and teeth, which needs vitamin D to be absorbed, and iron for making haemoglobin to carry oxygen (deficiency causes anaemia), which is absorbed better with vitamin C. Linking the partners (calcium with vitamin D, iron with vitamin C) earns extra marks.

Why are water and dietary fibre nutrients if they give no energy?

Water provides no energy but is essential because it makes up about two-thirds of the body, transports nutrients and waste in the blood, regulates body temperature through sweating, and is the medium for the chemical reactions in cells; an adult needs about 1.5 to 2 litres a day, more in Singapore's hot, humid climate. Dietary fibre also gives almost no energy but adds bulk, prevents constipation and helps a person feel full, which is why both are treated as essential parts of a healthy diet.

Why are some vitamins lost during cooking?

Water-soluble vitamins, the B group and vitamin C, dissolve into cooking water and are destroyed by heat, light and exposure to air, so long boiling or keeping food hot for ages leaches them away. Vitamin C is the most fragile. Fat-soluble vitamins (A, D, E and K) are far more stable because they are not lost into water, so the practical lesson is to steam or stir-fry vegetables quickly in a little water and serve them straight away.

SingaporeNutrition & Food Science

Nutrients and their functions: the macronutrients, vitamins, minerals, water and dietary fibre the body needs and what each one does

An N(A)-Level Nutrition and Food Science (SEAB 6073) overview of nutrients and their functions: the three macronutrients (protein, carbohydrate and fat) and the energy they give, the key vitamins (A, C and D) and minerals (calcium and iron), and water and dietary fibre, with links to every dot point and a worked nutrient-analysis.

Generated by Claude Opus 4.88 min readSEAB-6073Updated 2026-06-13

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this module demands
The three macronutrients and their energy
The micronutrients, water and fibre
How the nutrients are examined
Check your knowledge

What this module demands

Nutrients are the foundation of everything else in Nutrition and Food Science (SEAB 6073). Before you can plan a balanced meal, judge a diet-related disease or adapt a recipe for health, you must know what each nutrient does, where it is found and what happens when a person eats too little or too much. The written Paper 1 tests this with short recall questions ("state two functions of calcium"), with data-response questions that ask you to read a nutrition panel, and in longer questions that ask you to justify the nutrients a particular person needs. The same knowledge underpins the coursework food study, where you justify every ingredient choice. This overview ties the macronutrients, vitamins, minerals, water and fibre together and links to every dot point in the module.

You can see the full set of dot points at /sg-n-level/nutrition-and-food-science/syllabus/nutrients-and-their-functions.

The three macronutrients and their energy

The macronutrients are needed in large amounts. Protein and its functions is the body's building material, made of amino acids and used for growth and repair, with energy only as a backup. The key distinction for marks is high biological value (HBV) protein from animal foods, soya and quinoa, which has all the essential amino acids, versus low biological value (LBV) protein from most plant foods, which is missing one or more. Eating two LBV foods together, such as rice and dhal, is called complementation.

Carbohydrates and their functions are the body's main energy source. They split into sugars, starches and fibre. Sugars and starches supply energy, while too much free sugar leads to tooth decay and weight gain. This is the natural place to argue for wholegrain over refined choices, which links forward to diet-related disease.

Fats and their functions give concentrated energy, insulate the body, protect organs and carry the fat-soluble vitamins. The health distinction the examiner wants is saturated fat, usually solid at room temperature and linked to raised blood cholesterol and heart disease, versus unsaturated fat, usually liquid and the healthier choice.

Memorise the energy values exactly, because calculations depend on them: protein gives about 17 kJ per gram, carbohydrate about 17 kJ per gram, and fat about 37 kJ per gram. Fat is more than twice as energy-dense as the other two.

The micronutrients, water and fibre

Vitamins and minerals are micronutrients, needed in small amounts but vital. Learn the headline set: vitamin A for eyesight and skin; vitamin C for healthy gums and skin, for healing wounds and for absorbing iron (deficiency causes scurvy); vitamin D for absorbing calcium (deficiency causes rickets); calcium for strong bones and teeth; and iron for making haemoglobin to carry oxygen (deficiency causes anaemia). Vitamins also split into water-soluble (B group and C), easily lost in cooking water, and fat-soluble (A, D, E, K), which the body can store.

Water and dietary fibre close the module. Both give little or no energy yet are essential. Water makes up about two-thirds of the body, transports substances, regulates temperature and is the medium for chemical reactions, with a need of about 1.5 to 2 litres a day, more in Singapore's climate. Dietary fibre adds bulk, prevents constipation and helps a person feel full.

How the nutrients are examined

State functions and sources precisely. Recall questions reward exact answers: name the deficiency, give a real food source, state the function in one clear sentence. "Calcium is for health" earns nothing; "calcium builds strong bones and teeth and is found in milk and tofu" earns the mark.
Read and compare nutrition data. Data-response questions give a nutrition panel or table and ask which food is higher in fat or fibre, or to calculate energy. Use the energy values (about 17, 17 and 37 kJ per gram).
Justify nutrients for a person. Longer questions describe someone (a pregnant woman, a growing teenager, an older adult) and ask which nutrients they need and why. Match the nutrient to the life stage and explain the reason.

Analysing the nutrients in a chicken-and-rice meal

A student eats a plate containing 30 g of protein, 70 g of carbohydrate and 15 g of fat. Work out the energy it gives and judge how balanced it is.

step Recall the energy values

Protein and carbohydrate each provide about 17 kJ per gram; fat provides about 37 kJ per gram. These are the fixed values from the carbohydrate and fat dot points.

step Calculate the energy from each macronutrient

Protein: 30 g x 17 = 510 kJ. Carbohydrate: 70 g x 17 = 1190 kJ. Fat: 15 g x 37 = 555 kJ.

step Total the energy

510 + 1190 + 555 = 2255 kJ for the meal. Carbohydrate supplies the most energy, which suits a main meal built on a rice base.

step Judge the balance and improve it

The fat (15 g) contributes about a quarter of the energy from only a small mass, showing how energy-dense fat is. The meal has good protein for repair and plenty of carbohydrate for energy, but it lacks fibre, vitamins and minerals because there are no vegetables. Adding a serving of stir-fried greens supplies vitamin C, fibre and minerals, and a glass of water replaces fluid lost in Singapore's heat, turning an adequate meal into a balanced one.

Check your knowledge

A mix of recall and application questions covering the nutrients. Attempt them, then check against the solutions.

State the energy value, in kJ per gram, of protein, carbohydrate and fat. (3 marks)
Explain the difference between high and low biological value protein and give one food source of each. (3 marks)
Name the deficiency caused by a lack of iron and explain why iron is needed. (2 marks)
Explain why water-soluble vitamins are easily lost during cooking and give one way to reduce the loss. (2 marks)
Explain why water and dietary fibre are essential even though they give little or no energy. (2 marks)

Solutions

Q1: Protein about 17 kJ per gram, carbohydrate about 17 kJ per gram, fat about 37 kJ per gram. Fat is the most energy-dense, giving more than twice the energy of the other two for the same mass.
Q2: High biological value protein contains all the essential amino acids the body needs and comes from animal foods such as fish, eggs or milk, or from soya. Low biological value protein is missing one or more essential amino acids and comes from plant foods such as rice, nuts or beans. (Any one valid source for each.)
Q3: A lack of iron causes anaemia. Iron is needed to make haemoglobin in red blood cells, which carries oxygen around the body; without enough, a person feels tired and looks pale.
Q4: Water-soluble vitamins (B group and C) dissolve into cooking water and are destroyed by heat, so long boiling leaches them away. To reduce loss, steam or stir-fry vegetables quickly and serve them straight away, or use the cooking water in a sauce or soup.
Q5: Water gives no energy but makes up about two-thirds of the body, transports nutrients and waste, and regulates temperature. Dietary fibre gives almost no energy but adds bulk, prevents constipation and helps a person feel full, so both keep the body working properly.

Sources & how we know this

Singapore-Cambridge GCE N(A)-Level Nutrition and Food Science (Syllabus 6073) — Singapore Examinations and Assessment Board (2026)
My Healthy Plate and dietary guidelines — Health Promotion Board, Singapore (2026)