* Iron * Calcium * Zinc * Iodine * Sodium (salt) * References
Many minerals, such as iron and calcium, are essential for health. We get these minerals and other elements from our diet. While it is important that we get enough, too much of some of them can cause health problems.
Iron What is it?
* Iron is an essential mineral in the diet.
What does it do?
* It is needed to make haemoglobin, the red part of blood, that carries oxygen to all parts of the body. It is also important for the nervous system (for brain development and function), for body growth and to fight infections.
Where is it found?
* Iron is found in meat, especially red meat, liver, eggs, seafood, grains and cereals, legumes. Iron is absorbed easily from meat, but is not as readily absorbed from plant foods unless foods containing vitamin C are eaten at the same time. This is important for vegetarians. Pregnant women are often given iron supplements to make sure the baby gets enough.
What happens if we don't get enough?
* Anaemia, or low haemoglobin in the blood, from iron deficiency can occur at times of rapid growth (such as before birth and in the early months) and when there is regular blood loss (eg. when a girl starts having periods). * Energy levels, growth and development may be affected. * Some research has found that almost a quarter of South Australian babies and young children had low iron levels, and some were showing problems because of this. * Children with very low iron levels may have developmental delay, and may be more likely to have some behaviour problems such as ADHD (Attention Deficit Hyperactivity Disorder).
What happens if we get too much?
* This is not likely from the diet, but iron supplements are poisonous in excess, especially for children.
Calcium What is it?
* Calcium is an essential mineral in the diet.
What does it do?
* Calcium is needed to build and strengthen bones and teeth. Bones act as a store of calcium. It is also used for blood clotting, nerve and muscle functioning, and may help to lower blood pressure.
Where is it found?
* Milk and milk products, canned fish with bones, tahini (sesame seed paste) and tofu are foods that contain calcium. Most cereal and vegetable foods contain some calcium, but it is not always well absorbed from these foods. Children and adults who cannot have dairy foods for some reason can use soymilk that has added calcium. If this is not possible, it may be wise to take calcium supplements.
What happens if we don't get enough?
* Low calcium intake can lead to poor bone growth, and in older people, osteoporosis (thinning of bones). Building strong bones in childhood is important for later health. This requires plenty of calcium in the diet and exercise. See the topic 'Milk for toddlers'
What happens if we get too much?
* No known problems.
Zinc What is it?
* Zinc is a mineral needed in the diet.
What does it do?
* Zinc is needed for growth, vision, taste and smell. It helps the body heal wounds and fight infections.
Where is it found?
* Meat, seafood, eggs and dairy products are the best sources. There is some in wholegrain cereals, nuts and legumes, but it may not be as well absorbed from these foods.
What happens if we don't get enough?
* Slow growth, poor wound healing and slow recovery from infections, skin rashes, and loss of taste and appetite. This may occur in young children who eat a lot of high fibre foods and very few animal foods.
What happens if we get too much?
* An excessive zinc intake from supplements may affect the absorption of other minerals.
Iodine What is it?
* Iodine is a substance needed in the diet.
What does it do?
* Iodine is used by the thyroid gland to make thyroid hormone. This is necessary for growth, nervous system development and energy. It regulates the speed at which body processes work.
Where is it found?
* Seafood, vegetables (if there is iodine in the soil where they are grown), meat, eggs, milk, iodised salt.
What happens if we don't get enough?
* Goitre (enlargement of the thyroid gland) and hypothyroidism can occur. This is especially harmful in babies as it can affect development. Iodine deficiency is a particular problem in isolated areas of developing countries, but rarely in Australia. There has recently been some concern that iodine levels could be falling in Australia, perhaps because we no longer use iodised salt.
What happens if we get too much?
* A large excess of iodine in the diet can also cause goitre, but this is rare.
Recent research
Recent research done in Australia showed that South Australian children are 'borderline' deficient in iodine and have significantly larger thyroid glands than international norms. For the group to be 'borderline' deficient, some individuals would be low in iodine. Iodine is essential for the production of thyroid hormones which regulate body metabolism.
The authors recommend that all edible salt in Australia have iodine added (iodised). Iodised salt used to be widely used, but recently it is not often used. Iodised salt is available in supermarkets in boxes/packets with green labelling. Sea salt does not contain iodine. There is currently debate about whether manufacturers of food need to also use iodised salt.
Sodium (salt) What is it?
* Sodium an element which is part of common salt.
What does it do?
* A small amount of sodium is needed for normal body functioning. It is involved in many cell processes.
Where is it found?
* Sodium is found in table salt, baking soda, and MSG (monosodium glutamate). It is also present in many foods, especially processed ones.
What happens if we don't get enough?
* This would be rare, as sodium is hard to avoid, and most of us have far more than we need. A lot is lost from the body with excessive sweating or diarrhoea, so more may be needed in these cases.
What happens if we get too much?
* Some people are more likely to get high blood pressure if there is a lot of salt in their diet. It is wise to avoid salty foods as much as possible. * The National Health and Medical Research Council (NHMRC) has made some recommendations for sodium intakes for Australians o Babies 0 to 6 months 120 mg per day o Babies 7 to 12 months 170 mg per day o Children 1 to 3 years recommended 200-400 mg per day, upper limit 1,000 mg per day o Children 4 to 8 years recommended 300-600 mg per day, upper limit 1,400 mg per day o Children 9 to 13 years recommended 400-800 mg per day, upper limit 2,000 mg per day o Young people 14 to 18 years recommended 460 to 920 mg per day, upper limit 2,300 mg per day o Adults 460-920 mg per day, upper limit 2,300 mg per day