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By Shaun Holt

Minerals are defined as being naturally occurring chemicals which are solid at room temperature, represented by a chemical formula, usually not resulting from the activity of living organisms and with an ordered atomic arrangement.

Some minerals are necessary for the normal functioning of the body’s cells. Relatively large quantities of macrominerals are needed (calcium, chloride, magnesium, phosphate, potassium, sodium) and smaller amounts of trace minerals (chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, zinc).

As with any other form of dietary supplement, it is important to have an adequate intake but can also be harmful if too much is ingested. If people have a good, healthy, well-balanced diet then they may not be deficient in any minerals. However, if someone is known to be deficient in one or more minerals, or more likely, they want to make certain that they are not deficient; a good multi will provide a top-up of the key minerals with no risk of overdosing.

In this article, 5 of the most common minerals are discussed.


Many people ask about selenium supplements as concentrations in New Zealand soils are low and therefore so are the levels in our food. Selenium is also of interest because of its antioxidant properties, with antioxidants thought to be beneficial for health as they protect cells from damage.

Studies also suggest that people who consume lower amounts of selenium could have an increased risk of developing certain cancers. There is an easy way to top up levels for anyone who is concerned as Brazil nuts contain very high amounts of selenium and a couple will provide most of your recommended daily intake.


Potassium deficiencies are more common in people who take diuretic (urine) medications, those who have physically demanding jobs and athletes. Potassium plays a role in every heartbeat and so that’s around 100,000 times a day that it is useful! For people with low potassium, diets with more high potassium fruits and vegetables such as bananas and spinach are recommended or a supplement containing potassium.


This mineral is needed to maintain a normal blood pressure and it also keeps bones strong and the heart rhythm steady. Many people do not eat enough foods with magnesium, and as is often the case, green leafy vegetables are a good source, as are nuts. Fortunately however, symptoms due to magnesium deficiency such as nausea, fatigue or numbness are rare. Supplements have been shown to reduce blood pressure, reduce the risk of stroke and lower the risk of diabetes. Over dosage is extremely rare as the kidneys are very effective at eliminating excess amounts of magnesium in the urine.


This mineral which humans require in trace amounts is known to enhance the action of insulin. The most common reason that people consider taking chromium supplements is because it is thought to help to control type 2 diabetes and/or the glucose/insulin responses in people who are at high risk of developing diabetes.

Many studies have looked at this and the results have been difficult to interpret given that some of the studies occurred in China where a large proportion of the population were chromium deficient. Overall though, the weight of evidence is in favour of a beneficial response.


Finally, zinc is rapidly becoming recognised as the most effective supplement for reducing the severity and duration of the common cold. The Cochrane review on this topic concluded that "zinc (lozenges or syrup) is beneficial in reducing the duration and severity of the common cold in healthy people, when taken within 24 hours of onset of symptoms". It is also thought to strengthen the immune system generally and help wound healing when applied topically, but there is less supporting evidence for these indications.