Micronutrients and water (SACE Stage 2 Nutrition)
“Describe the functions, food sources and deficiency effects of key vitamins and minerals, and explain the role of water in the body”
Micronutrients are vitamins and minerals needed in only small amounts, but they are essential for processes such as bone formation, immunity, oxygen transport and energy release. Water is not a nutrient that gives energy, yet it is the medium for nearly every body reaction. You should describe the function, food sources and deficiency effects of key examples, and explain why water balance matters.
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What this dot point is asking
You need to explain why nutrients needed in tiny quantities are still essential, give specific examples of vitamins and minerals with their functions and deficiency effects, and describe the roles of water.
Vitamins
Vitamins are organic compounds the body cannot make in sufficient amounts, so they must come from food. They are grouped by how they dissolve:
- Fat-soluble vitamins (A, D, E, K) dissolve in fat, are stored in the liver and fatty tissue, and can build up to toxic levels if taken in excess.
- Water-soluble vitamins (the B group and vitamin C) dissolve in water, are not stored well and any excess is excreted in urine, so a regular intake is needed.
Examples to know:
- Vitamin C supports the immune system and the formation of collagen for healthy skin, gums and blood vessels. Deficiency causes scurvy (bleeding gums, poor wound healing). Sources include citrus fruit and capsicum.
- Vitamin D helps the body absorb calcium for strong bones. Deficiency causes rickets in children. It is made in skin exposed to sunlight and found in oily fish and fortified foods.
- Vitamin A is needed for vision and healthy skin; deficiency causes night blindness.
Minerals
Minerals are inorganic elements with a wide range of structural and regulatory roles:
- Calcium builds bones and teeth and is needed for muscle contraction and nerve function. Long-term shortage contributes to osteoporosis (weak, brittle bones). Sources include dairy, leafy greens and fortified foods.
- Iron is part of haemoglobin, which carries oxygen in red blood cells. Deficiency causes anaemia (tiredness, pallor, breathlessness). Sources include red meat, legumes and leafy greens.
- Iodine is needed to make thyroid hormones that control metabolic rate; deficiency causes goitre (an enlarged thyroid). Sources include seafood and iodised salt.
Iron from plant foods (non-haem iron) is absorbed less easily than iron from meat (haem iron). Eating a vitamin C source in the same meal, such as orange juice with a lentil dish, increases non-haem iron absorption.
Why small amounts still matter
Micronutrients often act as cofactors or are built into important molecules. A single iron atom sits at the centre of each haemoglobin group, and tiny amounts of iodine control the whole body's metabolism. Because they are not used as fuel, the amount needed is small, but the consequences of going without are specific and serious, which is why deficiency diseases such as scurvy, rickets and anaemia are named after particular missing nutrients.
Water
Water makes up roughly 60 percent of body mass and is the medium in which the body's chemistry takes place. Its roles include:
- acting as the solvent for reactions and for transporting nutrients and wastes in blood,
- regulating body temperature through sweating,
- lubricating joints and protecting tissues,
- removing wastes through urine.
Water balance is maintained by matching intake (drinks and food) with losses (urine, sweat, breath). Dehydration occurs when losses exceed intake, causing thirst, fatigue, headache and, if severe, organ failure. Water needs rise with heat and exercise.
Step 1: Read the symptoms
Suppose a case describes tiredness, pallor and breathlessness in a teenage girl on a low-meat diet. Group the symptoms before naming a nutrient.
Step 2: Identify the likely deficiency
These are the classic signs of iron-deficiency anaemia. Iron is part of haemoglobin, which carries oxygen, so low iron means less oxygen reaches the tissues.
Step 3: Explain why this person is at risk
A low-meat diet supplies mostly non-haem iron from plants, which is absorbed less easily than haem iron from meat, and menstruation increases iron losses, raising her needs.
Step 4: Recommend an evidence-based fix
Increase iron-rich foods (legumes, leafy greens, lean red meat) and pair plant iron with a vitamin C source, such as orange juice, to boost non-haem iron absorption. Naming the nutrient, the reason and the absorption tip is the full-mark structure.
- Thinking vitamins give energy
- Micronutrients supply no kilojoules; they enable the reactions that release energy from macronutrients.
- Assuming more vitamins are always better
- Excess fat-soluble vitamins are stored and can become toxic, so megadoses are not harmless.
- Naming the wrong deficiency
- Match the nutrient to its disorder: vitamin C with scurvy, vitamin D with rickets, iron with anaemia, iodine with goitre, calcium with osteoporosis.
- Forgetting water as a nutrient
- Even though it has no energy value, water is essential and is treated as a nutrient in nutrition.
In short, micronutrients and water are needed in small or non-energy quantities yet are indispensable: each vitamin and mineral has a specific job, and water is the medium that makes the body's reactions possible.
Exam-style questions
Questions in the style of SACE Board exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
2018 SACE Stage 2-style1 markA study has found that middle-aged women have a high risk of developing osteoporosis. Identify one mineral that can reduce the risk of developing osteoporosis.Show worked answer →
One mark for naming a correct mineral.
Calcium is the standard answer. Calcium is the main mineral in bone tissue, and an adequate calcium intake helps build and maintain bone density, reducing the risk of osteoporosis.
The mineral phosphorus also contributes to bone structure and would be accepted, but calcium is the expected response.
2019 SACE Stage 2-style1 markState one function of vitamin E in the human body.Show worked answer →
One mark for one correct function.
Vitamin E acts as an antioxidant: it protects cells and cell membranes from damage caused by free radicals. This helps prevent the breakdown of polyunsaturated fats in cell membranes.
Either wording - antioxidant, or protects cells/membranes from free radical (oxidative) damage - earns the mark. Vitamin E is fat-soluble, which is relevant to how it is stored and lost during cooking.
2019 SACE Stage 2-style2 marksIdentify one micronutrient that is important for women to consume during pregnancy. Explain why.Show worked answer →
One mark for naming the micronutrient, one mark for the reason.
Folate (folic acid) is the strongest answer. Folate is essential for the formation of the neural tube in the developing embryo, and adequate folate in early pregnancy greatly reduces the risk of neural tube defects such as spina bifida (1 mark for folate, 1 mark for the neural tube reason).
Iron is an acceptable alternative: iron requirements rise in pregnancy to support the increased blood volume of the mother and the growth of the baby, helping prevent anaemia.
Practise this
Sources & how we know this
- Stage 2 Nutrition subject outline (2025 onwards) — SACE Board
- Stage 2 Nutrition: external assessment — SACE Board