Magnesium vital to life - and fireworks

IN our latest Friday science lecture Dr Pauline Balac, a senior lecturer in biology at Huddersfield University looks at the importance in our diet — and out of it — of magnesium

Magnesium: Symbol Mg; Alkaline earth metal; Atomic number 12; Atomic weight 24.31.

The best image of magnesium that most of us have is from school chemistry laboratories when the magnesium ribbon is set alight and burns with a bright white flare.

This was the basis of electrically-ignited flash bulbs for photography and today magnesium powder is still used in fireworks and marine flares.

In fact, magnesium is the third most abundant element in seawater, after sodium and chlorine.

However, magnesium also plays a vital role in sustaining life as it is essential for the cells of all known living organisms and is needed in more than 300 biochemical reactions in our bodies.

It helps keep normal muscle and nerve function, keeps heart rhythm steady, promotes a healthy immune system and keeps bones strong.

It also maintains normal blood pressure, helps regulate blood sugar levels and is involved in energy metabolism and protein synthesis.

Magnesium is therefore a vital component of a normal healthy diet and we need about 300mg of it every day. (For comparison of other minerals, we only need about 14mg of iron but 800mg of calcium every day.)

Green vegetables like spinach are a rich source of magnesium because the centre of the chlorophyll molecule, which makes plants green, contains magnesium. Legumes such as peas and beans, nuts, seeds and wholegrains are also good sources of magnesium.

Bread made from wholemeal flour provides more magnesium than bread made from refined white flour. Hard water also contains more magnesium than soft water. It is the dissolved magnesium ion which contributes to the tartness and taste of natural mineral waters.

In 1618 a farmer in Epsom, Surrey, tried to give his cows water from a well. They refused to drink because of the water’s bitter taste. However, the farmer noticed that the water seemed to heal scratches and rashes.

The fame of Epsom salts spread. Eventually they were recognised to be hydrated magnesium sulfate. Epsom salts have been traditionally used for treating minor cuts and bruises or as a laxative (“It went through me like a dose of salts!”) — magnesium ions ingested in large amounts are a laxative.

Adult human bodies contain about 24 grams of magnesium, with about half of it being found in bone.

Only about 1 per cent of magnesium is found in the blood, but the levels are kept very constant.

Other medical uses of magnesium compounds are as an antacid (milk of magnesia), as various antiseptics, to treat some heart arrhythmias and to delay labour in cases of premature labour.

Have you noticed that some products such as peanuts and pumpkin seeds have written on the packet “Naturally high in magnesium”?

There is some concern among health professional that we may not be taking in enough magnesium in our diets.

This may be due to us eating more refined foods and also because of modern fertilisers that contain no magnesium.

Recently research suggests a link between low dietary magnesium and the metabolic syndrome.

The metabolic syndrome is a disease condition identified by three or more factors including obesity, high blood pressure, high blood lipids and high blood glucose.

Diets that provide plenty of fruits and vegetables, which are a good source of potassium and magnesium, are associated with lower blood pressure.

Foods higher in these two minerals are usually also higher in fibre and lower in sodium and fat.

Some dietary surveys have suggested that a higher magnesium intake may reduce the risk of having a stroke or coronary heart disease.

A recent article in the European Journal of Nutrition indicated that “people with the highest dietary magnesium intake had a 64 per cent lower risk of having the metabolic syndrome compared to people with the lowest magnesium intake”.

It also suggested that elderly people with a higher magnesium intake were less likely to be overweight and had better blood glucose control.

So what is the best way to get your 300mg of magnesium per day?

You could try two shredded wheat (55mg), 1oz of cashews (75mg), 1 cup of soybeans (75mg), 1 baked potato with skin (55mg) and 1 cup of spinach (75mg).

That would give you 335mg of magnesium in a day.

Eating a variety of wholegrains, legumes and green vegetables every day will help provide sufficient magnesium and maintain normal storage levels of this mineral.

It should not be necessary to take magnesium supplements unless there is an underlying health condition such as diabetes, alcoholism or malabsorptive problems.

Doctors can evaluate magnesium status in the above conditions and decide on the need for supplementation.