What are vitamins, which ones matter, and what do they do?
Vitamins as micronutrients, fat-soluble vitamins A, D, E and K and water-soluble vitamins B group and C, their sources, functions and deficiency diseases.
A focused CCEA GCSE Food and Nutrition answer on vitamins, covering the fat-soluble vitamins A, D, E and K and the water-soluble vitamins of the B group and vitamin C, with their sources, functions and deficiency diseases.
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What this dot point is asking
CCEA wants you to know that vitamins are micronutrients needed in small amounts, the difference between fat-soluble and water-soluble vitamins, and the sources, functions and deficiency diseases of the main ones: A, D, E and K, the B group and C.
What vitamins are
Vitamins split into two groups by what they dissolve in.
Fat-soluble and water-soluble vitamins
This difference explains the cooking advice for vitamin C and why a daily supply of B and C vitamins matters.
The main vitamins
| Vitamin | Good sources | Main function | Deficiency |
|---|---|---|---|
| A | Liver, carrots, milk, oily fish | Vision (especially in dim light), healthy skin | Poor night vision, dry skin |
| D | Oily fish, eggs, fortified margarine, sunlight | Works with calcium for strong bones and teeth | Rickets (children), osteomalacia (adults) |
| B group | Wholegrains, meat, eggs, milk, pulses | Release of energy from carbohydrate; healthy nerves | Tiredness, poor growth (varies by B vitamin) |
| C | Citrus fruit, blackcurrants, peppers, broccoli | Healthy gums and tissue, iron absorption, healing | Scurvy (bleeding gums, slow healing) |
Vitamins E and K are also fat-soluble: E acts as an antioxidant protecting cells, and K is needed for normal blood clotting.
Keeping vitamins in food
Water-soluble vitamins, especially vitamin C, are easily destroyed by heat, light and air, and dissolve into cooking water. To reduce losses: prepare vegetables just before cooking, cook in a little water for a short time (steam or microwave), and serve straight away.
Why deficiency matters
Because vitamins control so many processes, even a small shortage causes problems. Scurvy (lack of vitamin C) and rickets (lack of vitamin D) are the two named deficiency diseases CCEA expects you to know, along with the idea that water-soluble vitamins must be replaced daily.
Examples in context
- Example 1. Why oranges help you absorb iron
- Vitamin C helps the body absorb iron from food, so drinking orange juice or eating a vitamin C rich food with an iron-rich meal improves iron uptake. This is a useful link between a vitamin and a mineral, and explains advice for people at risk of anaemia.
- Example 2. Fortified margarine and vitamin D
- Margarine is fortified (vitamins added) with vitamins A and D by law. This helps people who eat little oily fish or get little sunlight still get vitamin D for healthy bones. It connects vitamins to food labelling and to public health.
- Example 3. Vitamin needs in pregnancy
- Pregnant women are advised to take folic acid (a B vitamin) before and during early pregnancy to help prevent neural tube defects such as spina bifida in the baby. The point CCEA rewards is matching a specific vitamin to the needs of a life stage.
Try this
Q1. Name the deficiency disease caused by a lack of vitamin C. [1 mark]
- Cue. Scurvy.
Q2. Explain why water-soluble vitamins need to be eaten regularly. [2 marks]
- Cue. They dissolve in water and are not stored in the body, so a fresh supply is needed each day.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA past-style6 marksExplain why vitamins C and D are important in the diet, giving sources, functions and the effect of a deficiency of each.Show worked answer →
Six marks: three for each vitamin (source, function, deficiency).
Vitamin C is found in citrus fruits, blackcurrants, peppers, broccoli and potatoes. It helps the body absorb iron, keeps connective tissue and gums healthy, and helps wounds heal. A deficiency causes scurvy, with bleeding gums, slow healing and tiredness.
Vitamin D is found in oily fish, eggs, fortified margarine and is made by the skin in sunlight. It works with calcium to build and maintain strong bones and teeth. A deficiency causes rickets in children (soft, bowed bones) and osteomalacia in adults (soft, weak bones).
Markers reward a source, a function and a named deficiency for each vitamin.
CCEA past-style4 marksExplain the difference between fat-soluble and water-soluble vitamins, and describe one way to keep vitamin C losses low when cooking vegetables.Show worked answer →
Four marks: the difference plus a cooking tip.
Fat-soluble vitamins (A, D, E and K) dissolve in fat and can be stored in the body, mainly in the liver, so they do not need to be eaten every day.
Water-soluble vitamins (the B group and C) dissolve in water, are not stored, so they are needed regularly, and they are easily lost into cooking water and destroyed by heat.
To reduce vitamin C loss: steam, microwave or boil vegetables in a little water for a short time, prepare them just before cooking, and serve straight away rather than keeping them hot.
Markers reward the soluble/storage difference and one valid method to limit vitamin C loss.
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