What do vitamins and minerals do in the body, and what happens when key ones such as vitamin C, calcium and iron are missing?
Describe the functions, food sources and deficiency effects of the main vitamins and minerals, including vitamins A, C and D, calcium and iron
A simple, focused answer on vitamins and minerals for N(A)-Level Nutrition and Food Science: the functions, food sources and deficiency signs of vitamins A, C and D, and the minerals calcium and iron, plus water-soluble versus fat-soluble vitamins.
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What this dot point is asking
SEAB wants you to describe what vitamins and minerals do, name foods that supply the important ones, and explain the signs of deficiency. Unlike protein, carbohydrate and fat, vitamins and minerals are needed only in small amounts, which is why they are called micronutrients, but a shortage still causes serious problems. The marks come from knowing a small set well: vitamins A, C and D, and the minerals calcium and iron, plus the idea that some vitamins dissolve in water and some in fat.
The answer
Why vitamins and minerals matter
Vitamins and minerals do not give energy, but they keep the body working: they protect against disease, help other nutrients do their jobs, and build parts of the body such as bones and blood. Because the body needs only small amounts, they are called micronutrients.
Water-soluble and fat-soluble vitamins
Vitamins fall into two groups:
- Water-soluble vitamins (such as vitamin C and the B group) dissolve in water. The body cannot store much of them, so they are needed regularly, and they are easily lost into cooking water.
- Fat-soluble vitamins (A, D, E and K) dissolve in fat and can be stored in the body, so a daily supply is less critical.
The key vitamins to know
- Vitamin A is needed for good eyesight (especially seeing in dim light) and healthy skin. Sources: carrots, dark green leafy vegetables, liver and eggs. Deficiency causes poor night vision.
- Vitamin C is needed for healthy gums and skin and for healing wounds, and it helps the body absorb iron. Sources: oranges, guava, capsicum and other fresh fruit and vegetables. Deficiency causes bleeding gums and slow healing (scurvy).
- Vitamin D is needed to absorb calcium for strong bones and teeth. Sources: oily fish, eggs, and the action of sunlight on the skin. Deficiency causes weak, soft bones (rickets in children).
The key minerals to know
- Calcium builds and maintains strong bones and teeth and helps muscles and nerves work. Sources: milk, cheese, yoghurt, tofu and small fish eaten with bones (such as ikan bilis). Deficiency leads to weak bones and, later in life, osteoporosis. Vitamin D is needed to absorb calcium.
- Iron is needed to make haemoglobin in red blood cells, which carries oxygen around the body. Sources: red meat, liver, dark green leafy vegetables, and beans. Deficiency causes anaemia, with tiredness and a pale appearance. Vitamin C helps the body absorb iron.
Examples in context
Example 1. Calcium for growing bones. A glass of milk with breakfast supplies calcium for the strong bones a teenager needs during fast growth, and the vitamin D the body makes from a little time in the Singapore sun helps absorb that calcium. This everyday pairing shows the calcium and vitamin D partnership in action.
Example 2. Iron and vitamin C in one dish. A bowl of spinach and tofu soup with a squeeze of lime, followed by an orange combines a plant iron source (spinach) with vitamin C (lime and orange). The vitamin C boosts how much of the plant iron the body absorbs, a useful trick for someone who eats little or no red meat.
Try this
Q1. Name one vitamin needed for healthy gums and the healing of wounds, and one food that supplies it. [2 marks]
- Cue. Vitamin C; e.g. orange, guava or capsicum.
Q2. Explain the function of iron in the body and state one sign of iron deficiency. [3 marks]
- Cue. Iron makes haemoglobin in red blood cells to carry oxygen; deficiency causes anaemia (tiredness, pale appearance).
Q3. Explain why eating a vitamin C food with an iron-rich meal is a good idea. [2 marks]
- Cue. Vitamin C helps the body absorb iron from food, so more iron is taken in.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original8 marksA teenage girl often feels tired, looks pale and is told she may be short of iron. (a) State the main function of iron in the body. (b) Name two foods rich in iron. (c) Explain how vitamin C helps with iron, and name a food that supplies it. (d) Name one mineral important for strong bones and one vitamin needed to absorb it. (Section C style)Show worked answer →
(a) Iron is needed to make haemoglobin in red blood cells, which carries oxygen around the body.
(b) Any two iron-rich foods such as red meat, liver, dark green leafy vegetables (e.g. spinach or kai lan), or beans and lentils.
(c) Vitamin C helps the body absorb iron from food, especially iron from plant sources, so eating vitamin C with an iron-rich meal increases how much iron is taken in. A vitamin C food is orange, guava, capsicum or other fresh fruit and vegetables.
(d) Calcium is the mineral for strong bones and teeth, and vitamin D is needed to absorb calcium.
What markers reward: iron linked to haemoglobin and carrying oxygen, two genuine iron foods, a clear statement that vitamin C aids iron absorption with a correct food, and correctly pairing calcium with vitamin D.
Original4 marksA sailor in the past who ate only dried biscuits and salted meat for months developed bleeding gums and wounds that would not heal. (a) Name the vitamin he was lacking. (b) Explain why his diet caused this. (c) State one way to prevent it on a long voyage. (Section B style)Show worked answer →
(a) Vitamin C.
(b) Vitamin C is found in fresh fruit and vegetables, which his diet of dried biscuits and salted meat completely lacked. Vitamin C is needed for healthy gums, skin and the healing of wounds, so without it he developed bleeding gums and poor healing (scurvy).
(c) Any one sensible measure such as carrying fruit that keeps well (e.g. citrus fruit or limes), taking vitamin C tablets, or growing fresh vegetables or sprouts on board.
What markers reward: correctly naming vitamin C, linking the lack of fresh fruit and vegetables to the role of vitamin C in gums and healing, and one realistic prevention method.
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