Vitamins and Minerals

Tiny amounts, huge jobs

When you think about food, you probably think about energy and growing. But hidden inside your meals are some special nutrients that your body needs in only tiny amounts — yet without them, you would become ill. These are the vitamins and minerals.

Because you need only small quantities, scientists call them micronutrients ("micro" means small). Compare them to carbohydrates and protein, which you eat in large amounts and which you can read about in food groups and a balanced diet. Vitamins and minerals are different: a pinch is enough, but each one has a vital, specific job.

What is the difference?

• Vitamins are made by living things — plants and animals. There are several, named with letters such as A, C, D and the B group. Heat or long cooking can damage some of them.
• Minerals come from the earth — from rocks and soil. Plants take them up from the ground, and we get them by eating the plants, or by eating animals that ate the plants. Examples are iron, calcium and zinc. Minerals are not destroyed by cooking.

Some star vitamins and minerals

You need many micronutrients, but here are some of the most important and what they do.

Vitamin C keeps your skin, gums and blood vessels healthy and helps wounds heal. It is found in oranges, strawberries, peppers and broccoli. Long ago, sailors with no fresh fruit on long voyages got a disease called scurvy — until people discovered that eating citrus fruit prevented it. That was an early clue that hidden nutrients existed.

Vitamin D helps your body absorb calcium to build strong bones. Amazingly, your skin can make vitamin D when sunlight shines on it, which is why it is nicknamed the "sunshine vitamin". You also get it from oily fish and eggs.

Vitamin A helps your eyes, especially seeing in dim light, and keeps your skin healthy. It comes from carrots, sweet potatoes and leafy greens.

Calcium is a mineral that builds strong bones and teeth. It teams up with vitamin D, and is found in milk, cheese, yoghurt and green vegetables. Strong bones matter for your whole human skeleton.

Iron is a mineral your blood needs to carry oxygen. It is part of your red blood cells. Without enough iron you can feel tired and weak. Good sources are red meat, beans, lentils and dark green vegetables. Iron works closely with the respiratory system, because the oxygen it carries comes from the air you breathe.

Why variety is the secret

Notice how every vitamin and mineral has its own job and comes from different foods. No single food contains all of them. That is why the golden rule is variety: the more different healthy foods you eat, the wider the mix of micronutrients you get.

A simple trick is to "eat a rainbow". Different colours in fruit and vegetables often mean different vitamins and minerals:

• Orange carrots and sweet potatoes → vitamin A
• Red peppers and green broccoli → vitamin C
• Dark green spinach → iron and folate
• White milk and cheese → calcium

Getting the balance right

For most people, a varied, balanced diet supplies all the vitamins and minerals they need, with no pills required. A few people are advised to take a supplement — for example, vitamin D during dark winters — but this is best decided with a doctor, because having too much of certain vitamins can actually be harmful. As with so much in the body, balance is everything.

To keep more goodness in your food, try eating some fruit and vegetables raw, steaming rather than boiling for a long time, and using cooking water in soups so the vitamins that leaked out are not wasted.

Try it: vitamin C disappearing act

This activity shows that vitamin C is real, measurable, and sensitive to heat.

You will need fresh orange juice, a small amount of cornflour, water, iodine drops (from a first-aid kit, used with an adult), and two cups. Iodine turns blue-black with starch but the colour fades when vitamin C is present.

1. With an adult, mix a teaspoon of cornflour into half a cup of warm water, then let it cool. Add a few drops of iodine until it turns blue-black. This is your tester.
2. Slowly add fresh orange juice, drop by drop, stirring. Count how many drops it takes for the blue-black colour to fade away.
3. Now take some orange juice and boil it for a few minutes (an adult's job), then let it cool.
4. Repeat the test with the boiled juice. Count how many drops it takes this time.

Why it works: Vitamin C makes the dark iodine-and-starch colour fade. Fresh juice clears the colour quickly because it is full of vitamin C. Boiled juice takes more drops (or never fully clears) because heat has destroyed some of the vitamin C. You have just proved two things at once: that an invisible vitamin is really there, and why gently cooked or raw foods often keep more of their goodness.