Macronutrients and micronutrients and their functions for VCE Food Studies Unit 3 AoS 1
“The functions, food sources and deficiency or excess effects of carbohydrates, proteins, fats, vitamins, minerals and water in supporting health”
The three macronutrients (carbohydrates, proteins and fats) provide energy and building blocks, while micronutrients (vitamins and minerals) and water keep body systems working. You need each one's main function, a food source, and what happens with too little or too much.
What this dot point is asking
This dot point asks you to know the role of each nutrient, name reliable food sources, and explain the consequences of deficiency or excess. Strong answers connect a nutrient to a clear body function and to a specific dietary source.
Macronutrients
Carbohydrates are the body's main and preferred energy source, supplying about 16 kilojoules per gram. Complex carbohydrates such as wholegrains, legumes and starchy vegetables release energy slowly and add fibre, while simple sugars give quick energy. Too few carbohydrates leaves the body short of energy and forces it to break down fat and protein for fuel. A consistent excess of refined carbohydrates is linked to weight gain and type 2 diabetes.
Proteins build and repair body tissue and make enzymes, hormones and antibodies. They supply about 17 kilojoules per gram but are used for energy only when carbohydrate and fat are insufficient. Animal sources (meat, eggs, dairy, fish) provide all essential amino acids; plant sources (legumes, tofu, nuts, grains) can be combined to do the same. Protein deficiency impairs growth, immunity and wound healing.
Fats are the most energy-dense macronutrient at about 37 kilojoules per gram. They store energy, insulate the body, protect organs and carry the fat-soluble vitamins A, D, E and K. Unsaturated fats (olive oil, avocado, oily fish) support heart health, while excess saturated and trans fats raise the risk of cardiovascular disease.
Micronutrients
Vitamins are needed in small amounts to regulate body processes. They are either water-soluble (B-group and C, not stored, needed regularly) or fat-soluble (A, D, E, K, stored in body fat). Vitamin C supports immunity and helps absorb iron; vitamin D supports calcium absorption and bone health.
Minerals are inorganic elements with specific roles. Calcium builds bones and teeth and helps muscles and nerves work. Iron forms haemoglobin, which carries oxygen in the blood. Sodium helps regulate fluid balance, but excess sodium raises blood pressure.
Iron deficiency causes anaemia, leading to tiredness and poor concentration, and is common in adolescent girls and people on plant-based diets. Calcium deficiency over time contributes to weak bones and osteoporosis, especially in women after menopause. Knowing the nutrient, its function, a food source and its deficiency condition is worth full marks.
Water
Water makes up around 50 to 70 per cent of body weight. It transports nutrients and wastes, regulates body temperature through sweating, lubricates joints and is the medium for almost every chemical reaction in the body. Even mild dehydration reduces concentration and physical performance; severe dehydration is life-threatening.
Matching nutrients to life stages and groups
Many exam questions give a specific person or group, so you must link nutrients to needs:
- Infants and young children: high energy and protein for rapid growth; iron and calcium for blood and bone development.
- Adolescents: increased energy, protein, calcium for the bone-building growth spurt, and extra iron for girls due to menstruation.
- Pregnant and breastfeeding women: more folate (to prevent neural tube defects), iron, iodine, calcium and overall energy.
- Older adults: often lower energy needs but continued or higher needs for calcium and vitamin D (bone health), protein (to limit muscle loss) and fibre and fluid (digestion).
Pairing the nutrient with the group's specific need, rather than listing nutrients in general, is what earns the application marks.
A question asks you to identify two nutrients an adolescent needs in greater amounts and explain why, for 4 marks. Build the answer in steps.
Step 1: Choose the first nutrient and justify it
Choose calcium. Explain that adolescence is a critical time for building bone mass (peak bone-mass development), so a higher calcium intake supports the growth and strengthening of bones and teeth, reducing the risk of weak bones later in life. A source is milk, yoghurt, cheese or fortified alternatives.
Step 2: Choose the second nutrient and justify it
Choose iron (especially for adolescent girls). Explain that iron forms haemoglobin to carry oxygen, and that the growth spurt plus menstrual blood loss raises iron needs; too little causes anaemia, tiredness and poor concentration. A source is red meat, legumes or fortified cereals.
Step 3: Tie back to the group
Conclude that both increased needs arise from the rapid growth and development of adolescence (and, for iron, menstruation), showing you have linked the nutrient to the specific group rather than giving a generic function.
A common error is claiming vitamins or minerals provide energy. They do not. Only carbohydrates, proteins and fats (and alcohol) supply kilojoules. Vitamins and minerals help release and use that energy but contain none themselves. Stating that a vitamin gives energy is a marked error.
When answering, always pair a nutrient with a function and a food source, and if the question asks about a life stage or group, link the nutrient to that group's needs - for example, extra iron for adolescent girls or extra calcium for growing children and older adults. That targeted application is what separates a top answer from a generic list.
Exam-style questions
Questions in the style of VCAA 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.
Practice4 marksAn adolescent girl follows a vegetarian diet. Identify two micronutrients she may be at risk of consuming too little of, and for each, describe its function and a plant-based food source.
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Two marks for each micronutrient (function plus a plant source), applied to an adolescent vegetarian.
Iron (about 2 marks): iron forms haemoglobin, which carries oxygen in the blood; deficiency causes anaemia, tiredness and poor concentration. Adolescent girls have higher needs (menstrual losses) and plant iron is less easily absorbed. Plant sources include legumes, tofu, wholegrains and leafy greens (pair with vitamin C to aid absorption).
Calcium (about 2 marks): calcium builds bones and teeth and helps muscles and nerves work; adolescence is a key time for building bone mass. Plant sources include fortified plant-based milks, tofu set with calcium, and some leafy greens. Vitamin B12 (in fortified foods) is also a creditable answer. Name the nutrient, its function and a suitable plant source.
Practice3 marksExplain the role of water in the body and describe one effect of inadequate water intake.
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Three marks: roles of water (about 2 marks) and one effect of inadequate intake (1 mark).
Water makes up a large proportion of body weight and has several roles (about 2 marks): it transports nutrients and wastes, regulates body temperature through sweating, lubricates joints, and is the medium in which almost every chemical reaction in the body occurs.
Effect of inadequate intake (1 mark): even mild dehydration reduces concentration and physical performance and can cause headaches and tiredness; severe dehydration impairs body functions and is life-threatening. Name a clear role and a clear consequence.