* Vitamin A * Vitamin B1 (thiamin) * B2 (riboflavin) * B3 (niacin) * B6 (pyridoxine) * B 12 (cyano-cobalamin) * Biotin * Pantothenic acid * Folate (folic acid) * Vitamin C (ascorbic acid) * Vitamin D (cholecalciferol) * Vitamin E (tocopherol) * Vitamin K * Phytochemicals * References
Many advertisements suggest that we need to take vitamin supplements to get all the nutrients we need - but is this so? Do extra vitamins pep us up if we feel run down? In most cases the answer is 'no'.
It is much healthier to get our vitamins from food, the natural way. It is not true that all our food is so processed that it doesn't provide any goodness.
Many of the vitamins are involved in the chemical processes in our body that make energy. However, these processes are complex, and simply taking a vitamin pill won't provide us with an instant feeling of energy.
* It is not very hard to get enough vitamins from food, even if your diet is not 'ideal'. Eating well tends to make you feel better for lots of reasons. Junk food and a vitamin pill just aren't as good. * Scientists keep finding more 'goodies' in food - they are not all labeled as vitamins and are not all available as pills, but are important for good health. Foods provide these in the right proportions. See 'Phytochemicals' at the end of this list. * Having too much or an imbalance of vitamins can cause health problems, and some vitamins are quite poisonous in excess. It seems that enough is important, but more is not better. * Some vitamins are affected by cooking, especially those in vegetables. To minimise this, use only a little water and cook for only a short time. This gives a better flavour and texture too. Stir-frying and microwaving are also good.
Vitamin A What is it?
Vitamin A is a fat-soluble nutrient found in many foods. It can also be made in the body from substances like beta-carotene, which is water-soluble.
What does it do?
* Vitamin A keeps eyes healthy. * It makes the lining of body surfaces (ie. the mucous membranes) smooth and healthy, helping to prevent infection. * Carotenoids (like beta-carotene), as well as being a source of Vitamin A, are anti-oxidants, so may help prevent cancer.
Where is it found?
* Vitamin A is in cheese, liver, butter and margarine. * Carotenoids are in all orange, green and red vegetables, and are especially high in carrots.
What happens if we don't get enough?
* This is very rare in Australia, but is a big problem in developing countries. Deficiency can affect growth and worsen infections. Mild deficiency can also cause poor night vision, and full blindness if severe.
What happens if we get too much?
* Too much vitamin A is poisonous and can cause birth defects. However, it seems that carotenoids are not harmful - though your skin will go yellow if you eat a lot of carrots. Both types of vitamin A are stored well in the body.
Vitamin B1 (Thiamin) What is it?
* Like all the B group vitamins, thiamin is water-soluble. It is not well stored and we need a regular intake. Processing and cooking foods lowers the amount available (ie. some can be lost in cooking water), but it is not difficult to get enough in normal diets.
What does it do?
* Vitamin B1 takes part in many chemical reactions in the body. It helps make energy and keeps the nervous system healthy.
Where is it found?
* It is found in breakfast cereals, bread, nuts, pork, and Vegemite**. There is a little of it in most vegetables.
What happens if we don't get enough?
* Two groups of people are at risk of thiamin deficiency. Those who live on polished rice and little else may get a disease called beri-beri, and alcoholics may develop Wernicke-Korsakoff's Syndrome as a result of B1 deficiency. The nervous system and heart may be affected by these conditions.
Vitamin B2 (Riboflavin) What is it?
* Vitamin B2 is a water-soluble nutrient similar to vitamin B1.
What does it do?
* It helps the body to produce energy.
Where is it found?
* Vitamin B2 is found in breakfast cereals, eggs, milk, (though it is destroyed if milk is exposed to the sun), liver, meat, Vegemite**, and in small amounts in green vegetables.
What happens if we don't get enough?
* This is rare, but it can cause cracking of the skin around the mouth and slow growth in children.
Vitamin B3 (Niacin) What is it?
* Vitamin B3 is similar to vitamin B1, but it can also be made in the body from an amino acid (part of protein) called tryptophan.
What does it do?
* Vitamin B3 helps with energy production.
Where is it found?
* It is found in cereals, especially whole-grain, Vegemite**, nuts, some vegetables and all protein foods (meats and seafoods).
What happens if we don't get enough?
* This is most unlikely on a mixed diet. People who eat maize and little else can develop skin problems and general weakness, as maize protein is low in tryptophan - if severe, this can be 'pellagra', a disease caused by lack of niacin. Alcoholics can also have a niacin deficiency.
Vitamin B6 (Pyridoxine) What is it?
* Vitamin B6 is similar to vitamin B1.
What does it do?
* It is used in making proteins, nerve chemicals and blood.
Where is it found?
* Vitamin B6 is found in cereals, bread, bran, meat, seafood, fruit and vegetables.
What happens if we don't get enough?
* Deficiency can cause weakness, nerve and skin problems, and anaemia. This is most unlikely, except among alcoholics.
What happens if we get too much?
* Very large amounts can cause nerve damage.
Vitamin B12 (Cyano-cobalamin) What is it?
* Vitamin B12 is a water-soluble vitamin that is well stored in the body and is not affected by cooking.
What does it do?
* It helps to make genetic material in new cells, and is involved in making nerves and keeping them healthy.
Where is it found?
* It is in all animal foods, but not in vegetable foods. Strict vegans get a little from soil bacteria on foods such as mushrooms and from fermented foods, but can become deficient - this is a particular problem in pregnancy and when breastfeeding, and babies can be affected.
What happens if we don't get enough?
* Anaemia and nerve problems can occur, or developmental delay in babies. Vegan mothers need to take B12 supplements. * Some people are unable to absorb B12 because they have little stomach acid. This leads to a type of anaemia called pernicious anaemia, and these people need injections of the vitamin.
Biotin What is it?
* Biotin is a B-group vitamin that doesn't have a number. It is made by micro-organisms (bugs) in the gut, so we don't need to get it in our food. However there is plenty of it in eggs, dairy foods, cereals and seafood. If you eat a lot of raw egg white, this can stop biotin being absorbed and deficiency can occur. This is very rare.
What does it do?
* Biotin helps you to produce energy.
Pantothenic acid What is it?
* This is also a B group vitamin with no number. Again, it is made by gut micro-organisms, and is also in nearly all foods, so deficiency is not likely.
Folate (Folic Acid) What is it?
* Folic acid is a water-soluble vitamin that tends to be affected by heat during cooking.
What does it do?
* It is involved with B12 in making genetic material in new cells, and also helps build proteins.
Where is it found?
* Good sources of folate are grains and cereals (especially whole-grain), green vegetables, legumes, some fruit and nuts, and liver. There is some in eggs, seafoods, meats, milk (except for goat's milk) and cheese.
What happens if we don't get enough?
* Anaemia, diarrhoea, and sore mouth can occur. * In pregnancy a lot of folate is needed to make new cells. It is now known that having plenty of folate just before and during the early months of pregnancy can reduce the risk of a group of abnormalities called neural tube defects in the baby. As it may be hard to get enough for this purpose from the diet, it is best to take it in tablet form when planning a pregnancy. See the topic 'Folic acid and spina bifida'.
Vitamin C (Ascorbic Acid) What is it?
* Vitamin C is a water-soluble vitamin that can be affected by heat and cooking. It is an anti-oxidant and helps fight infection. Humans are one of only a few animal species that can't make their own vitamin C. Dogs and cats don't need to eat it, for instance.
What does it do?
* Vitamin C keeps cells healthy, especially connective tissue - the structural tissue in the body that keeps it all together.
Where is it found?
* It is found in fruit and vegetables, especially citrus, tropical fruits (paw-paw, pineapples, but not banana particularly), capsicum, cabbage, cauliflower and tomatoes.
What happens if we don't get enough?
* Scurvy can occur in people who eat no fruit or vegetables, but is rare these days. Symptoms include bruising, bleeding gums, poor wound healing, and muscle and nerve problems.
What happens if we get too much?
* Large amounts do not prevent colds, and could be dangerous. It can cause kidney stones and possibly damage blood vessels.
Vitamin D (Cholecalciferol) What is it?
* Vitamin D is a nutrient found in fats, but it can also be made in our bodies from sunlight on our skin.
What does it do?
* Vitamin D regulates calcium and phosphorus, so is important for strong bones. It is also involved in cell growth and immunity.
Where is it found?
* It is present in oily fish, liver, butter, margarine and eggs. * In Australia where there is plenty of sunshine, most of us do not need to get vitamin D from our diet. People such as the elderly and others who almost never go outside, especially if they have dark skin, are more likely to become deficient and are more reliant on food sources.
What happens if we don't get enough?
* Bone diseases may occur - rickets in children (which affects the growth of bones) or osteomalacia (thinning of the bones) in adults.
What happens if we get too much?
* Because it is stored in fat, too much vitamin D is poisonous. It can damage the kidneys and stunt the growth of children. It is not possible to get too much from sunlight, as the body just makes what it needs.
Vitamin E (Tocopherol) What is it?
* Vitamin E is a nutrient found in vegetable oils. It is stored in body fat.
What does it do?
* Vitamin E is an anti-oxidant that helps stop cell damage. It is most needed when poly-unsaturated oils are eaten; fortunately the vitamin and these oils are usually in the same foods. There has been interest in the use of vitamin E to prevent heart problems, but research seems to show that taking extra vitamin E does not lower the risk of heart disease.
Where is it found?
* Vitamin E is found in oily fish, vegetable oils, nuts, eggs and cereals.
What happens if we don't get enough?
* Deficiency is very rare, but it could cause damage to blood cells, muscles and nerves.
What happens if we get too much?
* Very high doses may be harmful.
Vitamin K What is it?
* Vitamin K is a fat-soluble vitamin that is made by bacteria (bugs) in the gut, so only a little is needed from food.
What does it do?
* Its main role is in helping blood clotting, but it probably has other functions in bones and kidneys.
Where is it found?
* Vitamin K is found in green vegetables and soybeans, but most comes from gut micro-organisms. Vitamin K is also added to infant formulas.
What happens if we don't get enough?
* Bleeding problems are possible in newborns unless they have an injection of vitamin K at birth, so this is done routinely in Australia and many other countries. Deficiency does not occur in older children or adults except with some medical conditions. See the topic 'Vitamin K'.
What happens if we get too much?
* Natural vitamin K is safe, but too much of the synthetic form is poisonous.
Phytochemicals What are they?
* Phytochemicals are found in plants but are not identified as vitamins. They are thought to be good for our health, and many of these chemicals are being investigated at present.
What do they do?
* They are likely to have many roles in health. Some are anti-oxidants which prevent cell damage, help fight cancer, lower cholesterol and help the body fight infection, while others act as mild hormones, helping to relieve menopause symptoms (phyto-oestrogens).
Where are they found?
* Phytochemicals are widespread in plant foods, but there is particular interest at present in vegetables, legumes (especially soy beans), garlic, tea and various seeds and nuts.