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| Vitamins, minerals and supplements |
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Reviewed by Dr Dan Rutherford, GP
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What are vitamins?
Vitamins are essential substances that cannot be manufactured by the body. We need small amounts of vitamins for growth and development. Without vitamins the body cannot survive.
The term vitamin is derived from the phrase vital amine. There are two types.
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Fat-soluble vitamins (A, D, E and K) are usually found in meat and meat products, animal fat and vegetable oils, dairy products and fish. They are transported around the body in fat, and your body stores any excess in the liver and fatty tissues. This means you don't need to get them from food sources every day.
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Water-soluble vitamins (B, C, folic acid) are found in meat, fish, fruit, vegetables and wholegrains. They are transported around the body in water. This means your body can't store them because you pass the excess through urine. You need to eat foods containing these vitamins every day. Water-soluble vitamins can be destroyed by cooking, so steam and grill rather than boil.
How easy is it to get all the vitamins we need from our diet?
We all need vitamins to live a long and healthy life, and a varied diet is essential if we are to obtain the nutrients we need.
Plenty of foods naturally contain vitamins, and some popular foods such as breakfast cereals are fortified with vitamins and minerals.
That said, it is not always easy: fruit and vegetables age (an apple in a bowl loses vitamins hour by hour), and modern processing techniques have considerably reduced the vitamin and mineral content of many foods.
Try to eat a wide variety of fresh foods. Frozen vegetables are also a good option: they can often contain more vitamins than vegetables stored for a long time at room temperature.
What problems can vitamins cause?
Too little of just one vitamin may disturb the body's balance and cause health problems.
But taking too many vitamins can also be dangerous.
This is especially true of the fat-soluble vitamins A, D, E and K because it's harder for the body to get rid of any excess through urine - the most common way to eliminate waste products.
Which vitamins do we know about?
New vitamins are discovered occasionally, but we know of the following: A, B1, B2, B3, B5, B6, B10, B11, B12, B13, B15, B17, C, D, E, F, G, H, K, L, M, P, T and U.
Are vitamins and minerals the same thing?
Vitamins and minerals are two completely different things: minerals help the vitamins work.
The 10 most important minerals are:
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calcium
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iodine
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iron
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magnesium
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phosphorus
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copper
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manganese
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chromium
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selenium
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zinc.
There is a specific recommended daily allowance (RDA) for most minerals and vitamins.
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Vitamin | EU RDA
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| Vitamin A | 800mcg |
| Vitamin B1 | 1.4mg |
| Vitamin B2 | 1.6mg |
| Vitamin B6 | 2mg |
| Vitamin B12 | 1mcg |
| Vitamin C | 60mg |
| Vitamin D |
5mcg |
| Vitamin E | 10mg
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| Folic acid | 200mcg
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Mineral | . |
| Calcium | 800mg |
| Iodine | 150mcg |
| Iron | 14mg |
| Magnesium |
300mg |
| Phosphorus | 800mg |
| Zinc |
15mg |
Do I need to take a supplement?
Most of us get sufficient quantities of vitamins and minerals from our food. It may be necessary for some people to take a vitamin supplement, for example pregnant women and the elderly.
Where do vitamin supplements come from?
Most vitamin supplements have been extracted from natural foods.
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Vitamin A comes from fish-liver oil.
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Vitamin B comes from yeast or liver.
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Vitamin C is often extracted from small berries in roses.
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Vitamin E is extracted from soy beans or maize.
Vitamins may also be synthetically manufactured, but synthetic vitamins are not always as effective as their naturally-derived equivalent.
How should I store supplements?
Keep supplements in a dark, cool place or they will 'go off', just like apples in a bowl.
The best place to store vitamins is in the refrigerator - make sure there is a lid on the container.
A few grains of rice in the container will prevent moisture getting into the tablets.
What's the best time to take supplements?
The best time to take vitamins is during the day, after a meal.
Never take supplements on an empty stomach - they will quickly pass out in your urine. This is especially true for the B and C vitamins that dissolve in water.
The fat-soluble vitamins A, D, E and K can be stored in the body for up to 24 hours and are sometimes stored in the liver for even longer.
Other articles in this series
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Based on a text by Dr Carl J Brandt, GP
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Last updated 16.04.2007
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