Magnesium: the Forgotten Mineral

        Magnesium is critical for good health. It controls over 800 enzymes and hence a large number of essential body functions, including DNA repair. If magnesium is low these vital functions won’t work well and you won’t be as healthy as you should be. Rats deprived of magnesium have a 34% higher mortality. Those with the highest magnesium have a 40% lower risk of dying from cancer compared to those with the lowest.

Am I likely to be deficient in magnesium?

Unlike calcium and iron, you are likely to be deficient in magnesium. Why? The reason is simple. Magnesium has been progressively depleted from the soil. This is because fertilisers (unlike animal manure) don’t contain magnesium. To make matters worse the commonest herbicide, glyphosphate (Roundup) binds to magnesium as do many pesticides.  Most plant and animal food is now low in magnesium. Processing of food further depletes magnesium. One hundred years ago people obtained about 500mg of magnesium from their food. Today it is 175 -225mg and that’s simply not enough for good health.

Which foods give us magnesium?

        The main source of magnesium is green, leafy vegetables (the greener the vegetable the more magnesium in it). Another good source is nuts and a handful of nuts each day can help keep magnesium levels up. Seeds also contain magnesium. However there is less magnesium in vegetables today than in the past and you need to eat more of them to keep your levels up. Most people need to supplement magnesium to get adequate levels of this vital mineral.

Which foods deplete magnesium?

        Sugar depletes the body of magnesium. To process one molecule of fructose (half of sugar is fructose) takes eight of magnesium. Processed foods and alcohol also deplete the body of magnesium. Magnesium is needed for the detoxification of chemicals so chemicals in food deplete magnesium further. This includes chemicals like aspartame and monosodium glutamate (MSG). Phosphorus is fizzy drinks also depletes magnesium.

 The ratio of calcium to magnesium is especially important and for most people it is too high (this makes the body over-excitable –see below). So you need more magnesium if you take a lot of calcium in the diet. Milk and yoghurt are very high in calcium but contain little magnesium. Antacid drugs are usually high in calcium. Calcium supplements often create a relative magnesium deficiency.

Which drugs deplete magnesium?

Diuretics (water tablets), the pill, PPIs (acid-blocking drugs such as omeprazole and lansoprazole: the body cannot absorb magnesium without acid in the duodenum) and alcohol can all lead to magnesium deficiency. All drugs which containing fluoride such as atorvastatin, rosuvastatin, flecainide, fluoxetine, paroxetine and ciprofloxacin bind with magnesium and lower magnesium as does fluoride from toothpaste and dental procedures using fluoride. Generally speaking the more drugs you take the more likely you are to be magnesium deficient.

What else depletes magnesium?

        Stress depletes magnesium as magnesium is needed to break down stress hormones like adrenaline. The more stress you have the more magnesium you need. Diarrhoea  causes magnesium loss. Even healthy activities can deplete magnesium. Exercise, especially strenuous exercise, causes magnesium to be lost in sweat. Saunas do the same.

Calcium and Magnesium Work Together

 Calcium is needed to contract muscle and magnesium is needed to relax it again. If you lack magnesium you get over-excitability such as muscle jerks, tremors and cramps. The highest levels of magnesium are in the brain and heart so if you are deficient in magnesium problems often happen in these areas.

 As the heart is the most important muscle, magnesium deficiency can weaken the heart leading to hypertension and irregular heart rhythms. Magnesium is also known as nature’s tranquiliser because of its ability to relax the body. Lack of magnesium can cause anxiety, depression, and sleep disturbance. Other symptoms of low magnesium can be constipation, osteoporosis, kidney stones, tingling and numbness, premenstrual tension and memory problems. Magnesium deficiency can worsen irritable bowel syndrome and asthma.

What supplement should I take?

        There are different forms of magnesium. Many are poorly absorbed and can have a laxative effect. (In fact Epsom salt, which is magnesium sulphate is used as a laxative). Magnesium oxide (used in Milk of Magnesia) is also poorly absorbed and is a poor choice.

A good choice is magnesium citrate which is well-absorbed. A typical dose is 250mg twice daily but some people will need more; maybe double this, especially in the early stages. It is often said that once it causes a laxative effect you have taken too much. This is not entirely true and depends on the type of magnesium but is a rough guide. Other preparations that are well absorbed are magnesium lactate, magnesium L threonate and magnesium lactate. Avoid magnesium glutamate or magnesium aspartete. Ionised forms such as Re-mag are the Rolls-Royce of magnesium. They are very well absorbed and do not have a laxative effect but are expensive.

        Magnesium is extremely safe. Gradually increase magnesium until symptoms such as muscle twitches disappear. Supplements are available from health food shops and online.

        The only people who should not take magnesium (except under medical supervision) are those with severe kidney failure, bowel obstruction, myasthenia gravis or a very slow heart rate.

Epsom salts are well absorbed through the skin. A good way of obtaining magnesium is to put two or three cupfuls of Epsom salts in a hot bath and stay in for at least half an hour (avoid using soap and shampoos until the end of the bath). Because of the sulphur in it this will be like a spa bath (Epsom salts can be obtained from many chemists but you often have to ask as it may not be on the shelf). Magnesium is also absorbed through magnesium gels, sprays and oils which are widely available at health food shops.

What about a blood test?

Magnesium is difficult to measure and the test done on the NHS (serum magnesium) is virtually useless (although most doctors don’t realise this). You can be seriously deficient and have completely normal serum magnesium. Magnesium levels in the blood stay normal until a person is nearly moribund as the body won’t allow magnesium levels in the blood to drop.

Specialist labs such as Biolab ( can measure red cell magnesium which measures magnesium inside the cell and is far more accurate (but not perfect). This is not often necessary if obvious symptoms are present. Aim to have magnesium at the upper level of the normal range