Your body needs a number of vitamins and minerals to stay healthy. These nutrients provide a base so that many of the essential chemical reactions in your body such as cell growth and repair, metabolism and even muscle function can occur. But how do these nutrients work in the body and where can you find them in food?
What are vitamins?
Vitamins are nutrients that we all need for the body to work properly. Different vitamins have different functions. We need vitamin C to produce certain hormones and to help absorb iron from food. Because your body can’t make most vitamins — apart from vitamin D — you have to get them from the food you eat.
There are two types of vitamins:
- water-soluble vitamins — these can’t be stored in your body and need to be replaced regularly from your diet
- fat-soluble vitamins — these can be stored in your body but should still be part of a healthy diet.
You can find water-soluble vitamins (such as vitamins B6, B12, C and folic acid) in fresh fruit and green vegetables. It’s best to eat green vegetables raw, steamed or stir-fried — cooking in water increases the loss of vitamin C.
Fat soluble vitamins include vitamins A, D, E and K. Because these vitamins can be stored in the body, it’s possible for high intakes of them to result in harmful levels. This is unlikely to happen when vitamins are consumed from food, but it’s possible to overdose on high levels of fat soluble vitamins taken in supplement form. Fat soluble vitamins are less easily lost in the cooking process.
See our vitamins and minerals table for a more complete list of some common vitamins, their functions and sources in food.
What are minerals and trace elements?
Minerals and trace elements are inorganic elements we need in small amounts for the body to function. They are as essential as vitamins and you need to get them from the food you eat. For example, you need:
- calcium to make strong bones
- sodium for fluid balance and nerve function
- iron for oxygen transport in the blood and energy metabolism
- iodine for thyroid hormone function.
You can mainly find minerals and trace elements in meat, cereals, fish, milk and dairy foods, vegetables, dried fruit and nuts.
See our vitamins and minerals table for a more complete list of some common vitamins, their function and sources.
How can I get enough vitamins and minerals?
You should be able to get all the vitamins and minerals you need by eating a healthy balanced diet. Aim for at least five servings of vegetables and two serves of fruit each day. Your meals should contain moderate amounts of starchy foods (such as whole grains, potato, rice or pasta) and moderate amounts of protein-rich foods (this includes dairy products, eggs, meat, fish and pulses such as peas, beans and lentils).
What about supplements?
Supplements aren’t a replacement for a healthy varied diet so it’s generally best to get your vitamins and minerals from food, unless your doctor or accredited practising dietitian advises otherwise. For example, you may need an iron supplement if a blood test shows you have anaemia.
Some vitamins, particularly fat-soluble vitamins, can be harmful in excessive quantities. Too much vitamin A can cause skin changes and damage your liver, or if you’re pregnant it can harm your unborn baby.
You should always check with your doctor, pharmacist or accredited practising dietitian before taking any supplements, to make sure this is the best for you.
Vitamins and minerals at different life stages
Your vitamin and mineral requirements can vary and change at different times of your life. Some common examples of when you might have higher requirements include:
| Women who are pregnant or planning a pregnancy |
The National Health & Medical Research Council recommends women begin taking a supplement of 0.4 mg of vitamin B9 (folic acid or folate) daily for one month before conceiving and during the first 3 months of pregnancy. This is in addition to eating a diet rich in folate foods such as oranges, leafy greens and whole grains. Additional folate at this time has been shown to help reduce the risk of having a baby with a neural tube defect. |
| Women after menopause and men aged 70 plus |
The mineral calcium is especially important to help maintain strong bones and reduce the risk of the bone thinning disease osteoporosis. Calcium requirements at these ages are high and some people may need a calcium supplement as well as eating calcium-rich foods. |
| Older people, people with darker skins and those who wear concealing clothing |
There are many reasons why we need enough vitamin D — for one thing, it’s important for helping us absorb sufficient calcium. Although we can get some vitamin D from food, our main source is sunlight. Some people have a higher risk of being low in vitamin D because it’s harder for them to make sufficient vitamin D from sun. These include older people, especially those who are housebound, people with darker skins and people who wear concealing clothing. |
Vegetarians and vegans
It’s quite possible to get all the vitamins and minerals you need from a balanced vegetarian diet. The exception is vitamin B12 for vegans — this is only available in significant amounts in foods of animal origin which a vegan diet avoids. Vegans should look for foods fortified with vitamin B12 and they may also need a vitamin B12 supplement. An accredited practising dietitian or doctor can give you more advice.
Well-planned vegetarian and vegan diets can provide health benefits such as lower ‘bad’ LDL cholesterol levels and blood pressure, lower risk of developing coronary heart disease, high blood pressure and type 2 diabetes, and may even help lower cancer rates compared to those eating non-vegetarian diets. But like any other diet, a badly-planned vegetarian or vegan diet can still be nutritionally unsound. So the aim for people on vegetarian or vegan diets is to:
- eat five servings of vegetables and two serves of fruit every day
- eat plenty of iron-rich foods such as lentils, beans, nuts, pumpkin seeds, tofu and iron-fortified breakfast cereals
- if you avoid eggs and dairy foods, eat a mix of plant protein foods throughout the day such as beans, tofu, tempeh, whole grains, nuts and seeds to get the full range of amino acids
- eat Brazil nuts, sunflower seeds, barley and whole grains to keep your selenium levels up
- drink soya, rice or oat drinks fortified with calcium to ensure you get enough calcium.
Further Information
Dietitians Association of Australia www.daa.asn.au
Mayo Clinic. Dietary supplements www.mayoclinic.com/health/supplements/NU00198
Sources
American Dietetic Association (ADA). Position of the American Dietetic Association: Vegetarian Diets. Journal of the American Dietetic Association, Jul 2009; 109(7): 1266–1282.
Dietitians’ Association of Australia (DAA). Vitamins. [online] Deakin, ACT: DAA. [updated 21 Jan 2008, accessed 2 Aug 2010] Available from: http://www.daa.asn.au/for_the_public/smart_eating_for_you/nutrition-a-z/vitamins
Dietitians’ Association of Australia (DAA). Minerals. [online] Deakin, ACT: DAA. [updated 21 Jan 2008, accessed 2 Aug 2010] Available from: http://www.daa.asn.au/for_the_public/smart_eating_for_you/nutrition-a-z/minerals
Harvard School of Public Health. Vitamins: the Bottom Line. [online] Boston, MA: The President and Fellows of Harvard College. c2010 [accessed 13 Aug 2010] Available from: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/vitamins/index.html
National Health & Medical Research Council. Nutrient Reference Values - Dietary Folate. [online] Canberra, ACT: Commonwealth of Australia. c2009 [accessed 25 Aug 2010] Available from: http://www.nrv.gov.au/nutrients/folate.htm
Osteoporosis Australia. Preventing osteoporosis — Calcium. [online] Sydney, NSW: Osteoporosis Australia. c2007 [accessed 25 Aug 2010] Available from: http://www.osteoporosis.org.au/about/about_osteoporosis/preventing-osteoporosis-calcium
Osteoporosis Australia. Preventing osteoporosis — Vitamin D. [online] Sydney, NSW: Osteoporosis Australia. c2007 [accessed 25 Aug 2010] Available from: http://www.osteoporosis.org.au/about/about_osteoporosis/preventing-osteoporosis-vitamin-d
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