Vitamins and minerals - what do they do?
Reviewed by Dr Dan Rutherford, GP
Recommended daily amounts (RDAs)
Micro vs milli
Check the letters after the RDA carefully.
One microgram (mcg or µg) is a thousand times smaller than a milligram (mg).
Vitamins
|
Vitamin A (retinol) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Eyesight, growth, appetite and taste.
|
Night-blindness. |
800 micrograms |
Liver, fish-liver oil, carrots, green leafy vegetables, egg yolks, enriched margarine, milk products, yellow fruits. |
This vitamin is fat-soluble and so is stored in the body for a long time, especially in pregnancy. An overdose may be dangerous. |
Fatty acids. |
|
Vitamin B1 (thiamine) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Nervous system, digestion, muscles, heart, alcohol-damaged nerve tissues.
|
Tingling in fingers and toes, confusion, difficulties in maintaining balance, loss of appetite, exhaustion, weakened powers of concentration. |
1.4mg |
Liver,
yeast,
rice,
wholemeal products,
peanuts,
pork,
milk.
|
No danger. It dissolves in water, so any excess is passed in urine. |
High temperatures, alcohol and coffee. |
|
Vitamin B2 (riboflavin) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Growth, skin, nails, hair, sensitive lips and tongue, eyesight, the breakdown of protein, fat and carbohydrate. |
Itchy irritated eyes, itchy mucous membranes (nose/mouth/throat), itchy lips and skin. |
1.6mg |
Milk,
liver,
yeast,
cheese,
green leafy vegetables,
fish.
|
No danger. It dissolves in water, so any excess is passed in urine. |
Alcohol and light (this is why milk-cartons are better than bottles). |
|
Vitamin B6 (pyridoxine) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Preventing skin conditions,
nerve problems,
helps the body absorb protein and carbohydrate.
|
Skin inflammation. |
2mg - women taking the contraceptive pill may need more. |
Fish,
bananas,
chicken,
pork,
wholegrains,
dried beans.
|
May cause nerve problems in large doses. Evidence is conflicting about the maximum safe dose, so get medical advice before exceeding the RDA. |
The contraceptive pill, roasted or boiled food, alcohol and oestrogen (the female hormone). |
|
Vitamin B12 (cobalamin) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Making red blood and the formation of the nerves. |
Tiredness, breathing difficulties, dizziness, abnormalities in nerve tissue function. |
1 microgram |
Fish,
liver, beef,
pork, milk, cheese. |
No danger. It dissolves in water, so any excess is passed in urine. |
Water, sunlight, alcohol, oestrogen and sleeping pills |
|
Vitamin C (ascorbic acid) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Immune defence system, protection from viruses and bacteria, healing wounds, reducing cholesterol, cell lifespan, preventing scurvy. It's also a natural laxative. |
Tiredness, bleeding gums, slow-healing wounds. |
60mg |
Citrus fruits, kiwi fruit, berries,
tomatoes, cauliflower, potatoes, green leafy vegetables,
peppers.
|
Large doses can cause diarrhoea and nausea. Some scientists have argued that 1000-5000mg per day may damage your DNA. |
Boiling food, light, smoking and heat. |
|
Vitamin D properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Strong bones and teeth |
Unhealthy teeth,
osteomalacia (causes weakening of bones),
rickets in children.
|
5 micrograms |
Sunlight (the action of sunlight on the skin allows our bodies to manufacture vitamin D),
cod-liver oil, sardines, herring,
salmon, tuna,
milk and milk products.
|
This vitamin is fat-soluble so can accumulate in the body. Overdoses are dangerous. |
Mineral oil. |
|
Vitamin E (tocopherol) properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Fighting toxins - vitamin E is a powerful antioxidant. |
Weak muscles and fertility problems. |
10mg |
Nuts,
soya beans, vegetable oil, broccoli, sprouts, spinach,
wholemeal products,
eggs.
|
There is a slight risk of overdose, because vitamin E is fat soluble. |
Heat, oxygen, frost, iron, chlorine and mineral oil. |
|
Folic acid properties
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
Destroyed by |
| Production of red blood cells. It is essential in the first three months of pregnancy to prevent birth defects such as spina bifida, cleft palate or cleft lip. |
Tiredness due to anaemia, red tongue. |
200 micrograms. Women planning to conceive should take a daily supplement of 400mcg, continued for the first 12 weeks of pregnancy. |
Carrots,
yeast, liver, egg, yolks, melon,
apricots, pumpkin,
avocado, beans, rye and wholewheat,
green leafy vegetables.
|
No danger. It dissolves in water, so any excess is passed in urine. |
Water, sunlight, oestrogen, heat. |
Minerals
|
Calcium
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
| Strong bones and teeth, nerve function, muscle contraction, blood clotting. |
Poor teeth and brittle bones. |
800mg |
Milk, cheese, butter, yoghurt and green leafy vegetables. |
High doses can lead to headaches, stomach pain, high blood pressure and diarrhoea. Excess calcium can be deposited as kidney and gall bladder stones. |
|
Iron
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
| Red blood cells and muscle function, white blood cells and the immune system. |
Tiredness, irritability, difficulties concentrating. |
14mg |
Lean red meat, oily fish, egg yolks, green leafy vegetables, nuts, wholegrains and wholewheat. |
Iron is stored in the body and high doses (over 17mg) can lead to constipation, vomiting, nausea and diarrhoea. Very high doses can be fatal. |
|
Magnesium
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
| Converting energy from food, cell repair, building strong bones, teeth and muscles, regulating body temperature. |
Muscle spasms, and has been associated with heart disease, diabetes, high blood pressure and weak bones. |
300mg |
Green leafy vegetables, wholegrains and nuts. |
High doses can cause diarrhoea. |
|
Zinc
|
| Good for |
Signs of deficiency |
RDA |
Good sources |
Poisoning |
| Immune system, the breakdown of protein, fat and carbohydrate. |
Lesions on skin, eyes and in throat, loss of taste and smell, hair loss, diarrhoea, slow healing of wounds, growth problems in children. |
15mg |
Meat, shellfish, milk brown rice and wholegrains. |
High doses can lead to stomach cramps, nausea and vomiting. |
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