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Vitamins and minerals - what do they do?
Health and Nutrition > Health Centres
Reviewed by Dr Dan Rutherford, GP
Recommended daily amounts (RDAs)
Micro vs milli
Check the letters after the RDA carefully.
Minerals
Other articles in this series
Vitamins, minerals and supplements
Sources of vitamins
Sources of minerals
Vitamins and minerals -
tips for healthy living
Vitamins and minerals - what do they do?
Reviewed by Dr Dan Rutherford, GP
Recommended daily amounts (RDAs)
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. |
| 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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