Vitamin and mineral supplements: when are they needed?

by | Diet and Weightloss

Vitamin and mineral supplements: when are they needed?

Most people should be able to get all the vitamins and minerals they need by eating a balanced diet. However, there are some people who may need particular supplements at some stages of life.

Supplements of vitamins and minerals will not convert poor food choices into a healthy diet, but relevant quantities of particular vitamins or minerals may address specific deficiencies at certain times. Note however, that supplements with high levels of some vitamins and minerals may be harmful.

Before taking any nutritional supplements, ask your healthcare professional whether they can interfere with any of your medicines or health problems. If you have any particular medical problem, you should discuss it with your doctor before self-treating with supplements.


At some stages in life, women have increased nutritional needs and may need to take supplements to meet their requirements.


  • Iron: Women may need extra iron to make up for losses in heavy menstrual periods. This may occur in women who eat meat as well as those who follow a vegetarian diet, as the main problem arises from heavy blood loss. A blood test can confirm whether iron levels are low. Self-diagnosis is not advisable, as excess iron from supplements can be harmful.


  • Folate: is an important nutrient for the developing fetus. Taking supplements of folic acid (the manufactured form of folate) for at least one month before conceiving, until the 12th week of pregnancy helps reduce the risk of neural tube defects, such as spina bifida. A specific folic acid supplement is needed as the amount in most multivitamins is insufficient. A diet rich in natural folate is also important. Folate is found in leafy vegetables such as spinach, Asian greens and watercress, asparagus, broccoli, cauliflower, peas, and beetroot and also in legumes, nuts and seeds, oranges, wheatgerm, wholegrains, Marmite and Vegemite, milk, eggs and some fortified cereals.
  • Iodine: Food Standards Australia New Zealand has made it mandatory for the salt added to breads to be iodised. This provides adequate amounts of iodine for most people, but not necessarily during pregnancy. The NHMRC recommends that women take an iodine supplement of 150 micrograms each day when pregnant, breastfeeding or contemplating pregnancy.


Higher levels of some vitamins and minerals are needed during pregnancy and lactation. These are easily supplied by a diet based on the 5 food groups: vegetables; fruit; cereal/grain foods (especially wholegrain); milk, cheese and yoghurt (or plant-based alternatives with added calcium and vitamin B12); lean meat, poultry, fish, eggs, legumes, tofu, nuts and seeds.

Note, however, that pregnancy does not increase the need for all vitamins. High doses of some, especially vitamin A, may harm a baby’s normal development – so avoid supplements, including regular multivitamins, which contain vitamin A. Your pharmacist or doctor can help you identify which supplements are safe for use in pregnancy.

  • Iron. During pregnancy, a woman’s blood volume has to expand to meet her own and her growing baby’s needs. This means more iron is needed. Fortunately, the body’s ability to absorb non-haem iron from plant foods increases during pregnancy so routine iron supplementation is not usually recommended. However, all women should have their haemoglobin level checked on their first antenatal visit and again at 28 weeks. Good dietary sources of iron include lean red meat, seafood, eggs, legumes, wholegrains and green vegetables.
  • Folate. Folic acid supplements are needed 1 month before conception until the 12th week of pregnancy to help prevent birth defects.
  • Iodine. Iodine supplements are recommended for pregnant women, as it can be difficult to meet the higher iodine requirements at this time through diet alone. Food sources include iodised salt, seafood (amount varies), milk and bread (it’s mandatory to use iodised salt in most breads in Australia).
  • Calcium: Calcium supplements may be required for pregnant women whose diets are deficient, although requirements don’t increase during pregnancy. Calcium is necessary for the formation of the bones and teeth.
  • Vitamin D: Vitamin D requirements are not increased during pregnancy, but for women whose culture or religion does not permit exposing skin to sunlight, a supplement is recommended to keep bones healthy and prevent the baby from developing rickets. For others, a short period of 10-20 minutes exposure of the arms to sunlight (avoid the middle of the day in summer) enables the body to make vitamin D. Few foods, apart from cod liver oil, herrings, salmon and trout contain enough vitamin D to provide sufficient quantities. Small amounts are found in eggs and butter and are added to margarine spreads.
  • Vitamin B12: Those who do not consume animal products should take a vitamin B12 supplement during pregnancy and breastfeeding. Plant foods do not contain vitamin B12.
  • Omega-3 fatty acids. Fish and other seafood supply long-chain omega-3 fatty acids. Plant sources include flaxseeds (also called linseeds), chia seeds, walnuts and canola oil. Those who consume little or none of these foods can consider a fish oil supplement, or a pregnancy supplement containing omega-3s.


  • Iodine. The NHRMC recommends that all women who are pregnant, breastfeeding or considering pregnancy, take an iodine supplement of 150 micrograms each day.

Menopause and after

Despite claims, there are no nutritional supplements that have been proven to help with menopausal symptoms, but eating a healthy diet, exercising regularly and limiting alcohol intake should go a long way to help manage symptoms. Some supplements have been associated with adverse effects, for example Black Cohosh has been associated with rare but serious cases of liver disease.

  • Vitamin D and calcium. During menopause and after, calcium and vitamin D may be recommended to avoid osteoporosis (brittle and fragile bones) and limit the risk of fractures. Bones also need other minerals and vitamins, including those found in vegetables. Bone strength is also increased by weight-bearing exercise, such as walking, tennis and dancing and specific weight training programs designed by qualified exercise scientists.


Fad diets, and diets which exclude entire food groups such as grains, dairy products, carbohydrates or fruit, can lead to deficiencies, especially of calcium, magnesium, iron, folate and dietary fibre. Such diets have llittle long-term value for permanent weight loss, and are best avoided. Some very strict low kilojoule diets, including those that may be used before essential surgery in some obese people, may be deficient in some nutrients. A supplement is usually prescribed in such cases.


Some people, including children, with multiple food allergies may have a restricted diet that fails to supply adequate quantities of some nutrients. Ideally, a dietitian will help plan alternative sources of essential nutrients. However, there may be specific cases where a multivitamin/mineral supplement may be useful.


Those who avoid all animal products may become deficient in some vitamins, especially vitamin B12 and be at risk of lacking some minerals.

  • Vitamin B12: Vitamin B12 is found naturally only in animal products. Some soy drinks and meat alternatives and a few fortified breakfast cereals have added vitamin B12, but those who avoid all animal products need a B12 supplement. Products such as spirulina and comfrey contain a substance that resembles vitamin B12, but is not a suitable substitute.
  • Iron. Vegan and vegetarian diets are generally high in non-haem iron, the type of iron found in eggs, legumes. vegetables, wholegrains, seeds and nuts. Non-haem iron is not as well absorbed as haem iron, the type that makes up 40% of the iron in meat, poultry and fish. There is no evidence that those who follow a well-balanced diet without meat are any more likely to be deficient in iron than meat-eaters, but their iron stores may be lower. This means that vegetarians should not deviate from a well-balanced diet for any period. Combining foods rich in vitamin C with those containing non-haem iron improves absorption of iron. In practice, the easiest way to achieve this is to consume some fruit and/or vegetables at each meal.
  • Calcium. Those who avoid dairy milk should ensure they use legume or grain-based substitutes that have added calcium at appropriate levels (at least 100 mg/100mL). Other sources of calcium include vegetables, such as Asian greens, almonds, tahini and wholegrains. Calcium supplements are an alternative.
  • Zinc. Meat is a good source of zinc. Alternatives include wholegrains, such as brown rice, oats, muesli and wholemeal bread, dairy products, legumes, green peas and nuts.


The athletes most likely to have problems with nutritional deficiencies are those that restrict energy intake or who have stringent weight-reducing practices. Female athletes may become deficient in iron and calcium and may need supplements of these nutrients.

People who cover their skin

People who cover their skin for cultural or religious reasons can easily be deficient in vitamin D and need to take a supplement. This is especially important during pregnancy and lactation, but also throughout life. Vitamin D is necessary for bone strength and muscle health. A deficiency is a major risk for osteoporosis.

Frail aged people

Many reasons can contribute to some elderly people becoming deficient in nutrients: depression; disability; forgetfulness; problems with teeth; and lack of interest in cooking, especially for those living alone. Some medicines or medical conditions may also inhibit a person’s ability to absorb nutrients from food.

  • Not eating enough can be a problem for some frail aged people. This can result in weight loss, loss of muscle, loss of strength and subsequent loss of independence. Various products available as oral, liquid or solid supplements provide extra kilojoules and protein and there are specialised products suitable for use in specific medical situations, such as renal disease, lung disease or cancer.
  • Medicines. The elderly are high users of medicines and some, for example antiacids, antibiotics, diuretics and laxatives, can interfere with vitamin and mineral absorption. In these cases, supplements may be needed.
  • Diagnosed deficiencies. Some older people may suffer from diagnosed deficiencies. This may be due to not eating enough, poor food choices or digestive problems that reduce the absorption of some nutrients. Specific supplements may be needed. A doctor or dietitian can assess the diet and make relevant recommendations.
  • Poor absorption. As some elderly people become frail, their ability to absorb some nutrients such as vitamin B12 decreases.
  • Indoors. Some may also find themselves confined indoors and this means a vitamin D supplement is necessary. However, claims that extra vitamin D can reverse age-related muscle dysfunction have not been proven.

Common nutritional deficiences in the frail aged include:

  • Protein deficiency. Inadequate protein intake leads to slow wound healing, a weakened immune system and muscle wasting. Good sources of protein include eggs, meat, poultry, fish and other seafood, milk, yoghurt, cheese, legumes (beans) and nuts.
  • Vitamin B12. The ability to absorb vitamin B12 can decline with age, so the elderly should ensure their diet has sufficient vitamin B12, by including foods such as meat, fish, poultry, eggs, milk, yoghurt or yeast spreads or soy drinks with added B12. A vitamin B12 supplement may also be needed.
  • Fibre. Some elderly people do not eat enough fruit, vegetables and whole grains, and so lack sufficient dietary fibre to support normal regular bowel function. High-fibre cereals and breads, legumes and more vegetables (can be incorporated into soups) as well as fruits and nuts provide dietary fibre.
  • Folate. Deficiency in folate is common in the frail aged who eat poorly. Good dietary sources include leafy vegetables such as spinach, Asian greens and watercress, asparagus, broccoli, cauliflower, peas and beetroot, legumes, nuts and seeds, oranges, wheatgerm, wholegrains, Marmite and Vegemite, milk, eggs and fortified cereals. Folate deficiency can result in anaemia, so taking a multivitamin containing folic acid (the manufactured version of folate) or a folic acid supplement can correct a deficiency.
  • Vitamin D and calcium. Osteoporosis is linked to lack of calcium and this can increase the risk of fractures. If dietary calcium intake is insufficient, a calcium supplement is recommended, as well as weight-bearing exercise to strengthen the bones. Vitamin D supplements may also be necessary, especially in those who are housebound or have limited sun exposure. In addition to helping prevent osteoporosis, there is some evidence that restoring healthy vitamin D levels can increase muscle strength and decrease falls.
  • Antioxidants are sold with claims they help boost the immune system and help prevent oxidative damage linked to a variety of conditions, including cataracts and memory loss, but there is no convincing evidence of their effectiveness. Fruit, vegetables and wholegrains are good sources of literally hundreds of these substances and are the best choice.

People with high alcohol intake

Heavy drinkers or those with a regular alcohol intake and poor dietary habits may become deficient in many nutrients, including thiamine (vitamin B1), folate, vitamin B12, and vitamins A and C.

Even moderate alcohol consumption can negatively affect how the body absorbs vitamin B12, increasing the risk of deficiency. Vitamin B12 supplements can be taken by mouth or sometimes may be needed by injection.

Always tell your doctor about supplements

Always tell your doctor and pharmacist about any vitamins or supplements you are taking. They may interact with your prescription medicines, leading to an adverse effect or have an effect on a condition you have, or an operation you may need to have. Supplements may make prescription medicines less effective, more effective or may increase their side effects. If you are on prescription medicines, don’t start taking vitamins and supplements without consulting your pharmacist or doctor first.


Buying medicines or supplements from international websites is not advised. The products on such websites are not regulated by the Therapeutic Goods Association and can have many problems. They can be counterfeit, out of date, stolen, contain pharmaceuticals, and be contaminated with pesticides, heavy metals or bacteria.

In Australia, vitamins and supplement products are either “Listed” or “Registered” by the TGA.

  • “Listed” products are prefaced with an “AUST-L”, and contain ingredients which have been approved as they are deemed to be of low risk. Listed products are not allowed to make claims for treatment of serious illnesses that would require a doctor to treat them.
  • “Registered” products are prefaced by “AUST-R”, and contain ingredients of higher risk, and as such have to supply safety, quality and efficacy data. They are used to treat more serious illnesses. If the manufacturer makes claims about a product’s effectiveness, it must be a registered product. However, the TGA does not usually conduct tests on the effectiveness of these products.