Vitamins as micronutrients: fat-soluble vitamins (A, D, E, K) and water-soluble vitamins (B group and C), their functions, food sources, deficiency effects, and how cooking affects them.

What this dot point is asking

You need to know that vitamins are micronutrients, the difference between fat-soluble and water-soluble vitamins, the functions and sources of the main ones, what deficiency causes, and how cooking affects them.

Fat-soluble and water-soluble vitamins

The main vitamins

Vitamin A (fat-soluble)

Needed for vision (especially in dim light), and for healthy skin and the immune system. The body can make it from beta-carotene in orange and green vegetables. Sources: liver, oily fish, dairy, carrots, spinach. Deficiency causes poor night vision.

Vitamin D (fat-soluble)

Helps the body absorb calcium for strong bones and teeth. Sources: oily fish, eggs, fortified foods, and the skin makes it in sunlight. Deficiency causes rickets in children and soft, painful bones in adults.

Vitamin E (fat-soluble)

An antioxidant that protects cells. Sources: vegetable oils, nuts and seeds.

Vitamin K (fat-soluble)

Needed for blood clotting. Sources: green leafy vegetables.

B group vitamins (water-soluble)

Help release energy from food and form red blood cells; folate (B9) is important before and during pregnancy. Sources: wholegrains, meat, eggs, dairy, green vegetables. Deficiency of some B vitamins causes anaemia (tiredness).

Vitamin C (water-soluble)

Needed for healthy skin and gums, wound healing, and to help absorb iron. Sources: citrus fruit, berries, peppers, potatoes. Deficiency causes scurvy (bleeding gums, slow healing).

How cooking affects vitamins

• Water-soluble vitamins (B and C) are easily destroyed by heat and dissolve into cooking water. To keep them: prepare just before cooking, use little water (steam, microwave or stir-fry), cook briefly, and serve at once.
• Fat-soluble vitamins are more stable to heat but can be lost into cooking fat.

Antioxidants

Some vitamins, including vitamins A, C and E, act as antioxidants. These help protect the body's cells from damage and are linked to a lower risk of some long-term diseases. Brightly coloured fruit and vegetables are good sources, which is another reason to eat a varied, colourful diet.

Why deficiencies matter

Because the body needs vitamins for many processes, a lack causes specific problems: vitamin A (poor night vision), vitamin D (rickets and weak bones), vitamin C (scurvy), some B vitamins (anaemia). A varied diet with plenty of fruit, vegetables and wholegrains usually supplies enough. Some groups need extra care: vegans may need a vitamin B12 supplement or fortified foods, and many people are advised to consider a vitamin D supplement in winter, when there is little sunlight.