Should you supplement your diet or not?


Supplements imply something good; a nourishing addition to our diet that adds to the quality of our nutritional intake to boost our body stores and maximise our health. However, to what extent do supplements deliver this improved health?

What are supplements?

On the whole when we talk about supplements we mean vitamins and minerals usually taken as pills or as a liquid, much like medicines.

There are 13 recognised vitamins that are required by the body for a normal healthy metabolism. Vitamins are considered vital nutrients that cannot be synthesised in the body, requiring consumption through diet. Prolonged absence of any of these vitamins leads to deficiency and serious illness.

Almost all of these vitamins are readily available via a healthy diet so true deficiency is relatively rare. Except for Vitamin D, this is obtained via exposure to sunlight. Commonly known deficiencies include night blindness (Vitamin A), scurvy (Vitamin C), anaemia (folate, B12) and rickets (Vitamin D). However, in countries like Australia these conditions are fairly rare unless there is an illness that affects the absorption or metabolism of the vitamin.

Dietary minerals are a group of over 20 chemical elements that are required by the body for normal metabolism. Important minerals that may be deficient in diets are calcium (bone health), iron (blood health), selenium (antioxidant), iodine (thyroid function & growth) and zinc (reproductive health and taste).

Who is taking vitamin and mineral supplements and for what health reason?

According to recent published data from the Australian National Health Survey approximately 1.3 million Australians are regularly taking some type of vitamin/mineral or herbal/natural remedy for the treatment of a range of chronic illnesses including arthritis, osteoporosis, asthma, diabetes and heart disease. Those more likely to use supplements included people over the age of 60 years, women, and people with lower levels of education and income.

When should we be taking vitamin and mineral supplements?

Health professionals (general practitioners, physicians, pharmacists, accredited practising dietitians) use an evidence-based framework in their management of supplementation therapy. Vitamins and minerals are prescribed following a rigorous diagnostic framework and an identified need.

Common situations where multivitamin and mineral therapy is warranted include:

Lifestyle conditions:

  • Pregnancy (increased requirements for folate to prevent neural tube defects e.g. Spina Bifida, and increased requirements for iron)
  • Breastfeeding (increased requirements for calcium)
  • Strict vegetarians (vegans) may lack iron and Vitamin B12
  • Elderly (high risk of Vitamin D deficiency due to staying indoors)

Medical Conditions:

  • Diet-related (not bleeding related) anaemias (iron, folate or B12)
  • Malabsorptive disorders (pernicious anaemia, Chron's disease, celiac disease, Cystic Fibrosis, pancreatitis, bowel surgery, chronic diarrhoea)
  • Eating disorders such as anorexia nervosa where dietary intake is extremely low.

Before taking vitamins and minerals on a regular basis you should consult a health professional to make sure you actually need the supplement. Some vitamins and minerals interfere with medications so professional advice is critically important.

Is there any harm?

There is a recommended daily quantity required for each essential vitamin or mineral from the diet to maintain health and prevent illness. Each of these nutrients has a safe range and an upper limit above which some of these nutrients may be toxic. Unlike water-soluble vitamins that can be excreted via the urine if taken in excess, some minerals and fat-soluble vitamins cannot readily be excreted and can be harmful.

Some examples include:

  • High doses of Vitamin A can cause liver damage and birth defects during pregnancy
  • Excess Vitamin B6 can lead to nerve damage
  • Excess Vitamin C (above 1 g) can cause diarrhea and kidney stones
  • High doses of calcium can interfere with iron absorption and lead to anaemia
  • Excess folate (over 1.5g) can mask B12 deficiency and lead to anaemia

It is important to note that excessive doses of vitamins and minerals are highly unlikely from diet. Hypervitaminosis from diet is rare, for example you would have to eat 2-3kg of carrots each day to consume excessive beta-carotene that would turn your skin orange.


Focus on a balanced, healthy and bio-diverse diet to achieve nutrient adequacy. Include plenty of fresh fruits and vegetables (leafy greens and tomatoes), wholegrain breads and cereals, lean meat and skinless poultry, low fat dairy foods (include yoghurt), and healthy fats from vegetable and seed oils, nuts and oily fish.

For advice on the amount and kinds of foods to eat for health and wellbeing, visit

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