The 13 vitamins that humans need
Vitamins are often called micronutrients because they’re needed in such small quantities.
Most vitamins are known by a letter of the alphabet, although they also have a chemical name, for example, the chemical name for vitamin C is ascorbic acid. Vitamins can also be broadly classified into two groups – water-soluble vitamins (B group and C) and fat-soluble vitamins (A, D, E and K). Water-soluble vitamins are easily destroyed by high temperatures, light and processing, so it’s important that foods rich in these vitamins are eaten each day. In contrast, fat-soluble vitamins, which are generally found in foods with a high fat content, are more stable to heat and processing and can be stored in the body for long periods of time.
Recommended intakes
Our age, gender, body size, activity levels and lifestyle can all affect our nutritional needs for vitamins and so recommended intakes usually differ for men, women and children of different ages. For example, men tend to have higher requirements for most vitamins than women because they are bigger.In the UK, recommended vitamin intakes for men, women and children of different ages are set by the Department of Health.
The gold standard for each is called the Reference Nutrient Intake (or RNI) – formerly known as the recommended daily amount (RDA) or recommended daily intake (RDI).
The RNI is considered to be enough to meet the requirements of most people and is generally more than most of us need. If you’re meeting the RNI, the risk of being deficient in a certain nutrient is very small.
Furthermore, the Department of Health also sets a Lower Reference Nutrient Intake (LRNI) for each vitamin.
The LRNI is thought to be the amount that’s sufficient for just a few people with low requirements and most of us need more than this for good health. If you’re only meeting the LRNI – or are having less than this – there’s a good chance you may be deficient in that nutrient.
Finally, for some vitamins a ‘safe intake’ is set. This is used when there’s insufficient information to estimate a RNI or LRNI. It’s thought to be enough to meet the needs for almost everyone, without being so large that it causes unpleasant side effects.
Vitamin A Retinol and four caretinoids including beta carotene
Solubility: Fat
Recommended dietary alowance (male 19 - 70 years old) 900 µg
Deficiency disease: Low intakes of vitamin A can result in poor vision, dry skin, impaired reproduction and growth and an increased susceptibility to infection. In severe cases, it can lead to xeropthalmia or night blindness, which is often seen in third world countries. As retinol can be stored in the liver, a deficiency in this country is rare, although figures from the most recent National Diet and Nutrition survey show that 7% of men and 9% of women have vitamin A intakes below the LRNI. This increases to around one woman in five aged 19-24 years, indicating this group may be the most susceptible to low intakes.
Overdose disease: Hypervitaminosis.
Food Sources: There are two forms of vitamin A available to the body – retinol and beta-carotene, the latter of which is converted into vitamin A in the body. Retinol is found in foods of animal origin such as whole milk, cheese, butter, egg yolk, liver and oily fish. Margarines are also fortified with vitamin A by law. Beta-carotene is found mainly in dark green vegetables such as spinach and watercress, and yellow, orange and red fruits such as carrots, tomatoes, dried apricots, sweet potatoes, mangoes, liver, Orange, ripe yellow fruits, leafy vegetables, carrots pumpkins, squash, spinach, fish, soy milk.
Recommended doses per person in the UK:
Children Under 1 year µg 350; 1 to 3 µg 400; 4 to 6 µg 500; 7 to 10 µg 500
Males 11 to 14 µg600; 15+ µg 700
Females 11+ µg600; Pregnant µg 700
Why you need it:
Vitamin A is essential for reproduction and growth and development in children. It’s also necessary for keeping the skin, hair and eyes healthy and is particularly needed for vision in dim light. It also keeps the linings of organs such as the lungs and digestive tract healthy, helping the body to fight infections. Beta-carotene (which the body uses to make vitamin A) is also a powerful antioxidant and may help to protect against diseases such as cancer and heart disease.
Vitamin B1 Thiamine
Solubility: Water
Recommended Dietary Allowance: 1.2 mg
Deficiency disease: A mild deficiency of vitamin B1 results in tiredness, a poor appetite, headaches, muscle fatigue, poor concentration, depression, irritability and heart problems. In extreme cases, a condition called beri-beri results, which is sometimes seen in the third world.
Overdose disease: Drowsiness or muscle relaxation
Food sources: Wholegrain cereals, especially bread, fortified breakfast cereals, porridge oats and brown rice, are good sources of vitamin B1. Other foods that contain this vitamin include dairy products, yeast extract, pulses, nuts, seeds, red meat (especially pork) and offal, oatmeal, veggies, potatoes, liver, eggs.
Recommended doses per person in the UK:
Children under 1year 0.2 mg; 1 to 3 0.5 mg; 4to 10 0.7
Males: 11 to 14 0.9; 15 to 18 1.1; 19 to 50 1.0; 50+ 0.9
Why you need it :
Vitamin B1 is needed to release the energy from fats, proteins and carbohydrates so that it can be used by the body. It’s also essential for the nervous system and to keep the heart healthy. Furthermore, this vitamin is essential for growth in children and for fertility in adults.
B2 Riboflavin
Solubility: Water
RDA 1.3 mg
Deficiency Desease: The main problems of deficiency include poor growth, poor wound healing and skin, eye and mouth problems such as watery bloodshot eyes, flaky and dry skin, chapped lips and a sore tongue. Almost one in ten men and women have vitamin B2 intakes below the LRNI, rising to 15% of 19-24 year old women. Ariboflavinosis, Angular chelilites.
Food Sources: Bananas, popcorn,green beans, asparagus, milk, cheese, yoghurt, eggs, meats and offal are among the best sources of this vitamin, but fortified breakfast cereals, almonds, yeast extract and green leafy vegetables also contain some.
Recommended doses per person in the UK:
Children age Under 1year 0.4mg; 1 to 3 0.6; 4 to 6 0.8; 7 to 10 1.0
Males age 11 to 14 1.2mg 15+ 1.3mg
Females age 11+ 1.1mg Pregnant 1.4mg
Why you need it:
Vitamin B2 helps to release the energy from carbohydrates, fats and proteins. It’s also necessary for growth and is needed for healthy eyes, skin, hair and nails. Because this vitamin forms part of the enzymes that are needed for energy metabolism, you may need more if you are using up lots of energy.
B3 Niacin niacinamide
Solubility: Water
Recommended Dietary Allowance:16mg
Deficiency Disease: A deficiency of this vitamin is rare but causes skin problems, weakness, fatigue and a loss of appetite. In extreme cases, a condition called pellagra develops, which is mainly seen in third world countries. This is characterised by weight loss, skin problems, diarrhoea, depression and in severe cases, dementia.
Overdose disease: Liver damage
Food Sources: Vitamin B3 tends to be found in foods that are good sources of protein such as red meat, poultry, fish and nuts, although potatoes, pasta and yeast extract also contain this vitamin. Some foods such as bread and breakfast cereals are also fortified with niacin. The body is also able to make niacin from an amino acid (protein building block) called tryptophan. This means foods that are a good source of tryptophan such as eggs, milk, cheese and yoghurt, can contribute to recommended intakes for niacin, eggs, many vegetables, mushrooms.
Recommended doses per person in the UK:
Children age under 1 year 4mg; 1 to 3 8mg, 4 to 6 11mg; 7 to 10 12mg
Males age 11 to 14 15mg; 15 to 18 18mg; 19 to 50 17mg; 50+ 16mg
Females 11 to 14 12mg; 15 to 18 14mg; 19 to 50 13mg; 50+ 12mg; Pregnant 13mg
Why you need it
:
Like B1 and B2, vitamin B3 releases the energy from carbohydrates, fats and proteins so they can be used by the body. This vitamin is also involved in controlling blood sugar levels, keeping skin healthy and maintaining the proper functioning of the nervous and digestive systems.
B5 Pantothenic Acid
Solubility: Water
Recommend Dietary Allowance: 5mg
Deficiency Disease: As vitamin B5 is found in so many foods, deficiencies are rare. In fact, no cases have been seen in the UK, except in people who have followed an experimental diet that’s deficient in this nutrient. Paresthesia
Overdose disease: Diarrhea, possibly nausea and heartburn
Food sources: Meat, broccoli, avocado, offal, fish, poultry, red meat, wholegrains, nuts, eggs, yoghurt, beans and yeast extract.
Reccomended doses per person in the UK:
There’s no RNI. A safe intake for adults is considered to be 3-7mg
Why you need it:
Vitamin B5 helps release the energy from food and keeps the nervous system and skin healthy. It’s also needed to form certain stress hormones.
B6 Pyridoxine, pyridoxamine, pyridoxal
Solubility: Water
Reccomended Dietary Allowance: Reccomended 1.3 - 1.7mg
Deficiency disease: A deficiency in this vitamin is extremely rare but can lead to depression, headaches, confusion, irritability, cracking of the lips and tongue, numbness in the hands and feet, anaemia and lowered immunity. Anemia, peripheral neuropathy.
Overdose disease: Impairement of Proprioception
Food sources: Vitamin B6 is found in many foods including fish, offal, pork, eggs, yeast extract, brown rice, soya beans, oats, wholegrains, peanuts, walnuts, avocado, vegetables, tree nuts, bananas.
Recommended doses per person in the UK:
Children under 1 year old: 0.3mg; 1 to 3 0.7mg; 4 to 6 0.9mg; 7 to 10 1.0mg
Males: 11 to 14: 1.2mg; 15 to 18 1.5mg; 19 to 50 1.4mg; 50+ 1.4mg
Females 11 to 14: 1.0; 15+ and Pregnant: 1.2mg
Why you need it:
This vitamin is involved in the metabolism of protein, especially the conversion of tryptophan into niacin (see Vitamin B3). It’s also essential for the formation of red blood cells, antibodies and brain chemicals called neurotransmitters. Some women also report that vitamin B6 provides relief from the symptoms of premenstrual syndrome (PMS).
B7 Biotin
Solubility: Water
Recommended Dietary Allowance: 30µg
Deficiency disease: A deficiency is rare but can cause tiredness, nausea, thinning of the hair, skin rashes and depression. Enteritis
Food sources: Biotin is found in liver, yeast extract, beans, nuts, wholegrains, brown rice, milk, cheese, yoghurt, eggs, aw egg yalk, peanuts, leafy green, vegetables
Why you need it:
This belongs to the B vitamin group and is needed for energy production and to metabolise proteins and fats. It’s also needed for healthy skin and hair.
B9 Folic Acid, Folinic Acid
Solubility: Water
Recommended Dietary Allowance: 400µg
Deficiency disease: A mild deficiency may lead to tiredness, apathy and depression. Severe deficiency, results in a type anaemia. Low intakes prior to conception and during the early stages of pregnancy may increase the risk of having a baby with a neural tube defect such as spina bifida and cleft palate. Megaloblastic Anemia
Overdose disease: May mask symptoms of vitamin B12 deficiency
Food Sources: The best sources of this vitamin are dark green leafy vegetables, especially sprouts and spinach, green beans, peas, oranges, fortified breakfast cereals and bread, yeast extract, nuts, pulses, pasta, bread, cereal, liver.
Reccomended doses per person in the UK:
Children age under 1 year old: 50µg; 1 to 3 70µg; 40 to 6 100µg; 7 to 10 150µg
Males 11+ 200µg
Females: 200µg; Pregnant 300µg.
Why you need it:
This is a member of the B vitamin group and is essential for the formation of red blood cells. It also works with vitamin 12 to protect the nervous system and is needed for growth and the reproduction of cells. Good intakes when planning a pregnancy and in the first 12 weeks also protect against birth defects.
B12 Cyanacobalamin, hydroxicobalamin, methylcobalamin
Solubility: Water
Recommended Dietary Allowance: 2.4µg
Deficiency disease: A deficiency results in a particular type of anaemia called pernicious anaemia. However, in most adults, pernicious anaemia isn’t usually the result of a dietary deficiency of vitamin B12, but is caused by a lack of intrinsic factor, a protein that’s made by the cells in the stomach lining. This binds with vitamin B12 and then carries it to the small intestine where it’s absorbed. If too little intrinsic factor is present, a deficiency of vitamin B12 can result.
Overdose disease: Acne-like rash (?)
Food Sources: Animal foods such as meat, fish, chicken, eggs, milk, cheese and yoghurt are the best sources. Seaweed also contains vitamin B12 and fortified breakfast cereals have this vitamin added to them, making them a good source, too.
Recommended doses per person in the UK:
Children age under 1 year old: 0.3µg; 1 to 3 0.5µg; 4 to 6 0.8µg; 7 to 10 1.0µg
Males: 11 to 14 1.2µg; 15+ 1.5µg
Females: 11 to 14: 1.2µg; 15+ (also pregnant) 1.5µg
Why you need it:
Vitamin B12 is needed for the formation of red blood cells and is essential for normal nerve function, growth and the production of energy.
Important:
As vitamin B12 doesn’t occur naturally in plant foods, people who follow a vegan diet or strict vegetarian diet that limits eggs and dairy products may need to take a vitamin B12 supplement.
C Ascorbic Acid
Solubility: Water
Recommended Dietary Allowance: 90mg
Deficiency disease: Vitamin C is water-soluble and cannot be stored in the body, so it’s essential that vitamin C rich foods are consumed on a daily basis. A deficiency can lead to a loss of appetite, muscle cramps, dry skin, split hairs, bleeding gums, bruising, nose bleeds, infections and poor would healing. In severe cases scurvy develops, although this is uncommon in Britain.
Overdose disease: a slight diarrhea
Food sources: Fruit and vegetables are the main sources of vitamin C. Good sources include blackcurrants, berries, green leafy vegetables like Brussels sprouts, cabbage, spinach and broccoli, tomatoes, peppers, kiwi fruit, citrus fruits and their juices, liver.
Recommended doses per person in the UK:
Children age under 1 year old: 25mg; 1 to 10: 30mg
Males: 11to 14: 35mg; 15+ 40mg
Females: 11 to 14: 35mg; 15+ 40mg; Pregnant: 50mg
Why you need it:
Vitamin C is essential for the formation of collagen, which constitutes a major part of the connective tissue. This means it’s important for healthy skin, bones, cartilage and teeth and helps to heal wounds. Vitamin C also helps to prevent anaemia by assisting the absorption of iron. This vitamin is also a powerful antioxidant and so can help to protect the body against the harmful effects of cell-damaging free radicals that may increase the risk of heart disease and cancer.
Important:
Vitamin C is easily destroyed so take care when preparing and cooking vegetables to minimise losses. Keep vegetables in large pieces, prepare them just before they are to be cooked rather than leaving them to stand in water and steam rather than boil them. Cook them for the minimum amount of time too. If you do decide to boil veg, don’t add salt and use the cooking water to make gravies or sauces. Avoid adding bicarbonate of soda to the water too, as it speeds up the rate at which vitamin C is destroyed. Eat veg as soon as possible after cooking to prevent further losses, which occur when they’re kept warm. Finally, frozen veg often have a higher vitamin C content than poor quality 'fresh' produce because they’re prepared shortly after being picked.
D Cholecalciferol, Ergocalciferol
Solubility: Fat
Recommended dietary alowance: 10µg
Deficiency disease: A deficiency of vitamin D in babies and toddlers leads to soft bones and the development of rickets, characterised by deformed, bow-shaped legs. In adults, a prolonged deficiency of vitamin D leads to a disease called osteomalacia. Poor intakes of vitamin D also hinder the absorption of calcium, increasing the risk of osteoporosis is later life.
Overdose disease: hypervitaminose
Food sources: The main source of vitamin D for most people is sunlight – and as a result, it’s often called the sunshine vitamin. Ultra-violet rays from the sun act on a substance contained within the layer of fat beneath the skin to produce vitamin D. Dietary sources of vitamin D are limited to just a few foods, including oily fish like mackerel and sardines, eggs, liver, fortified breakfast cereals and margarine, which is fortified by law.
Recommended doses per person in the UK:
There’s no RNI for young adults.
Women and men over the age of 65 years need 10mcg
Why you need it:
Vitamin D, in conjunction with calcium and phosphorus, is needed to form strong bones and teeth. In particular, it helps to absorb calcium from the intestine and so can help to prevent brittle bone disease or osteoporosis in later life.
Important:
Even though it’s important to expose your skin to sunlight so that your body can make vitamin D, you don’t need to spend hours sunbathing! Just two hours of sunshine each week in the summer will maintain adequate levels throughout the rest of the year as this vitamin is stored in the body. Remember to follow all the usual sun safety advice and cover up during the hottest part of the day between 11-3pm, wear a sun screen and never let yourself burn.
E Tocopherols, Tocotrienols
Solubility: Fat
Recommended dietary alowance: 15mg
Deficiency disease: Deficiency is very rare, sterility in males and abortion in females, mild hemolitic anemia in newborn infants.
Overdose disease: Increased congestive heart failure
Food sources: Vitamin tends to be found in foods that are rich in fat such as vegetable oils, margarine, avocado, nuts and seeds. However, green leafy vegetables, eggs and wholegrains also contain some.
Recommended doses per person in the UK:
There’s no RNI. Safe intakes are considered to be above 3mg for adult women and above 4mg for adult men.
Why you need it:`
Vitamin E is a powerful antioxidant and may have benefits in helping to protect against diseases such as cancer and heart disease. Vitamin E is an essential part of the cell membranes and so helps wounds to heal and prevents scarring. It’s also needed for healthy red blood cells and nerves.
K Phylloquinone, menaquinone
Solubility: Fat
Recommended dietary alowance: 120µg
Deficiency disease: As our bodies make vitamin K, a deficiency is rare but may occur in people who are given drugs that destroy gut bacteria, for example, prolonged use of antibiotics. A deficiency can cause easy bruising and a prolonged bleeding time after an injury. Babies are given an injection of vitamin K when they’re born as their gut is free of bacteria and breast milk doesn’t contain much of this vitamin.
Overdose disease: Increases coagulation in patients taking anticoagulants
Food sources: As well as being made in the body, foods containing vitamin k include green leafy vegetables like spinach, asparagus, and broccoli, liver, milk, vegetable oils, wholegrains, oats and meat, beans, soybeans, eggs, strawberries, meat.
Recommended doses per person in the UK:
There’s no RNI. A safe intake is considered to be 1mcg per kilogram of body weight. For example, a person who weighs 70kg will need about 70mcg of vitamin K each day.
Why you need it:
Vitamin K helps the blood to clot after a cut or injury. Unlike most of the other vitamins, which need to be supplied by the diet, about half of the vitamin K we get is made in the large intestine by bacteria.
Important:
Probiotic drinks and yoghurts that contain acidophilus bacteria help to boost levels of gut bacteria, ensuring you make enough vitamin K. If you are taking a course of antibiotics, it’s a good idea to include products like these in your diet, as some drugs can inhibit the absorption of this vitamin.
Most nutrition experts agree it’s usually unnecessary to take vitamin supplements if you’re eating a balanced diet that’s packed with a range of nutrients. But it’s not always easy to know just how much of each vitamin you need – or what the best food sources are.