Which vitamins do we need, what does each one do, where do we get them, and what happens if we go short?
The function, dietary sources and effects of deficiency of the fat-soluble vitamins A and D and the water-soluble vitamins (the B group and vitamin C).
An SQA National 5 Health and Food Technology answer on vitamins, covering the function, dietary sources and deficiency effects of the fat-soluble vitamins A and D and the water-soluble vitamins of the B group and vitamin C.
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What this dot point is asking
The SQA wants you to know which vitamins are fat-soluble and which are water-soluble, state the function of each named vitamin, name foods that supply them, and describe what a deficiency causes.
Two groups of vitamins
Because water-soluble vitamins are not stored, you need a fresh supply often. Because they dissolve in water and are damaged by heat, the way food is cooked affects how much is left.
The fat-soluble vitamins: A and D
Vitamin A is needed for healthy eyes (especially seeing in dim light) and healthy skin, and it helps the body resist infection. Sources include liver, oily fish, eggs, cheese, butter and margarine, and orange or dark-green vegetables such as carrots and spinach (which contain carotene the body turns into vitamin A). A deficiency causes poor night vision and dry skin.
Vitamin D helps the body absorb calcium, which is needed to make strong bones and teeth. Sources include oily fish, eggs and fortified margarine, and it is also made by the skin in sunlight. A deficiency causes weak, soft bones: rickets in children and osteomalacia in adults.
The water-soluble vitamins: the B group and vitamin C
B group vitamins help release energy from carbohydrate during respiration and help keep the nervous system and the blood healthy. Sources include wholegrain cereals, meat, eggs, milk, and green vegetables. A shortage can cause tiredness because energy is released less efficiently.
Vitamin C has several functions you should know:
Sources of vitamin C are fresh fruit and vegetables: citrus fruit (oranges, lemons), blackcurrants, strawberries, peppers, broccoli and potatoes.
Keeping vitamins in food during cooking
Because the B vitamins and vitamin C are water-soluble and damaged by heat, a lot can be lost during preparation and cooking. To keep more:
- Prepare fruit and vegetables just before cooking, not long in advance.
- Cook in as little water as possible, or steam, and do not overcook.
- Use the cooking water (for example in a sauce or soup) so the dissolved vitamins are not thrown away.
Examples in context
Example 1. A child's packed lunch. Adding a satsuma and some pepper sticks to a lunchbox supplies vitamin C in a raw form, so none is lost in cooking, helping the child absorb iron from the rest of the meal and supporting healthy gums.
Example 2. Bone health in winter. In a Scottish winter there is little sunlight to make vitamin D in the skin, so eating oily fish and eggs and using fortified margarine helps supply vitamin D, which lets the body absorb calcium for strong bones.
Try this
Q1. Name the vitamin that helps the body absorb calcium for strong bones, and state one source. [1 mark]
- Cue. Vitamin D, from a source such as oily fish, eggs or fortified margarine (also made by the skin in sunlight).
Q2. State one effect of a deficiency of vitamin C. [1 mark]
- Cue. Slow wound healing or sore, bleeding gums (severe, long-term shortage causes scurvy).
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA N5 style4 marksDescribe the function of vitamin C and vitamin D, and state one food source of each.Show worked answer →
A 4-mark answer needs the function and a source for each of the two vitamins.
Vitamin C helps the body absorb iron from food and is needed to make connective tissue, so it helps wounds to heal and keeps blood vessels and gums healthy. A source is oranges (also acceptable: blackcurrants, peppers, broccoli, strawberries).
Vitamin D helps the body absorb calcium so that bones and teeth become strong. A source is oily fish (also acceptable: eggs, fortified margarine; it is also made by the skin in sunlight).
A further point that scores is that vitamin C also works as an antioxidant. For vitamin D, a deficiency causes weak bones (rickets in children, osteomalacia in adults).
Markers reward each correct function and each correct source. Stating "keeps you healthy" without a specific role earns nothing.
SQA N5 style3 marksExplain how a teenager could make sure they get enough vitamin C, and describe one effect of vitamin C deficiency.Show worked answer →
This question asks for practical advice plus a deficiency effect.
To get enough vitamin C the teenager should eat plenty of fresh fruit and vegetables every day, for example citrus fruit, berries, peppers and broccoli. Because vitamin C is destroyed by heat and lost into cooking water, eating some fruit and vegetables raw or lightly cooked (for example steamed) helps keep more of the vitamin.
An effect of vitamin C deficiency is that wounds heal slowly and gums become sore and may bleed, because vitamin C is needed to make connective tissue. A severe, long-term shortage causes the deficiency disease scurvy.
A further point that scores is that without enough vitamin C the body absorbs less iron, which can contribute to iron-deficiency anaemia.
Markers reward sensible food advice, the cooking-loss point, and a correct deficiency effect.
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Sources & how we know this
- SQA National 5 Health and Food Technology Course Specification — SQA (2017)
- British Nutrition Foundation - Vitamins and minerals — British Nutrition Foundation (2023)