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Sources of minerals

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Sources of minerals

Written by Dr Dan Rutherford, GP

Vitamins and minerals are essential for the maintenance of good health and the prevention of a number of diseases. In this article we look at the role of calcium, iron, selenium, magnesium, potassium and zinc in your diet.

Types of minerals

Minerals can be classified according to the amount your body needs:

major minerals are those we need more than 100mg of a day

minor minerals (trace elements) are those we need less than 100mg of a day.

Major minerals	Trace elements
Calcium	Chromium
Magnesium	Copper
Phosphorus	Iodine
Potassium	Iron
Sodium	Manganese
	Selenium
	Zinc

The minor minerals are not less important than the major ones â€“ all are needed for good health. Instead, deficiency depends on the natural availability of the mineral: if the mineral is found in lots of foods, it's unlikely your intake will be low.

Chromium, copper, iodine, manganese and phosphorus are found in a wide variety of foods, so deficiency is rare.

Sodium (salt) is the one mineral that we need to reduce in our diet.

Recommended daily amounts (RDAs)

Micro vs milli Check the letters after the RDA carefully.

One microgram (mcg or Âµg) is a thousand times smaller than a milligram (mg).

Calcium

This mineral is essential for strong bones and teeth. It also plays an active role in the body's immune system.

A lack of calcium in the diet is a contributing factor to osteoporosis, a condition that causes brittle bones in adults.

High levels of calcium are found in dairy products such as milk and yoghurt. On average 250ml (half a pint) of cows' milk or 150g yoghurt contains 300mg of calcium.

Some dairy products are high in fat, so you should meet your body's calcium needs by eating a diet containing a balance of dairy and non-dairy foods.

Non-dairy food sources of calcium include:

almonds, brazil nuts, hazelnuts

broccoli, curly kale, okra, spinach, watercress

dried apricot and figs

mackerel, oysters, pilchards, salmon, sardines

pulses, sesame seeds

tofu

calcium-enriched soya cheeses and milks.

The RDA for an adult is around 800mg.

Iron

Your body needs iron for healthy blood and muscles. It plays an essential role in the production of the body's white blood cells and in the activities of the immune system.

Lack of iron causes anaemia and symptoms such as tiredness and irritablilty. Women lose iron when they menstruate, and one in four British women don't get enough iron.

There are two types of iron in food:

haem iron found in meat and offal (essentially the iron from blood and muscle)

non-haem iron derived from some plants, grains and nuts.

Vegetable sources of iron also contain salts (oxalates and phytates) that affect how well the body can absorb the iron. This means you need to eat a lot more to get the iron that your body requires.

Oily fish and egg yolks are quite rich in iron, but also contain substances that affect your body's ability to absorb the iron.

The body can absorb:

20 to 40 per cent of the iron found in meat.

5 to 20 per cent of the iron found in vegetable sources.

How much iron the body can absorb also depends upon the presence of vitamin C and folic acid, which improve your body's uptake of this mineral.

Sources of iron include:

apricots, blackcurrants, figs, prunes, raisins

beans (including baked beans), lentils

broccoli, curly kale, peas, savoy cabbage, spinach, watercress

eggs

lean red meat, poultry or game, liver, kidney

liquorice

mackerel, oysters, sardines, tuna

nuts

wholegrain cereals and wholemeal bread.

The RDA for an adult is 14mg.

Magnesium

Magnesium helps to regulate potassium and sodium levels within the body, which are involved in the control of blood pressure.

It's also used in the release of energy, for building strong bones, teeth and muscles, and regulating body temperature.

Magnesium helps the body absorb and breakdown various other vitamins and minerals â€“ for example calcium and vitamin C.

Magnesium is found in lots of foods, and the following are good sources:

apricots, bananas, figs, prunes, raisins

brown rice, granary bread, wholemeal bread, wholewheat pasta, nuts, pulses

courgettes, green leafy vegetables, okra, parsnips, peas, sweet corn

lean meat

milk, yoghurt.

The RDA for an adult is 300mg. You should be able to get this amount from your daily diet.

Zinc

Zinc is an antioxidant and important for the maintenance of a healthy immune system.

It's found in water, meat and cereal products so deficiency is rare.

A lack of zinc may be associated with skin problems, slow healing of wounds and low sexual libido.

Good sources include:

brown rice and wholegrain breads.

cheese

crab, lobster, mussels, oysters, sardines

duck, goose, kidney, lean red meat, turkey, venison.

The RDA for an adult is 15mg.

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