Magnesium (Mineral Supplement)
Magnesium is one of the most important minerals in the human body – more than 300 enzyme-driven biochemical reactions depend on it. It is required for synthesising proteins and fatty acids, activating the B-vitamins, and plays a role in the absorption of calcium, potassium and Vitamin C. It is essential for the formation of bones and teeth and the transmission of nerve and muscle impulses. Magnesium is also important for regulating the heartbeat and for normal blood clotting. It has a relaxing effect on smooth muscle, including the uterus, and so may reduce the intensity of menstrual cramps.
The average adult body contains around 25g of magnesium, mainly within the bones and skeletal muscle. The European Food Safety Authority (EFSA) recommends a magnesium intake of 350 mg/day for men and 300 mg/day for women. The range for children is 170 to 300 mg/day, according to age.
Dietary sources of calcium include wheatgerm, seeds, nuts, bananas, figs, apricots, prunes, pulses, brewer’s yeast, cocoa and green leafy vegetables. Both a low and high intake of dietary protein inhibits magnesium absorption, as does the amount of phosphate, phytate, and fat in the gut. Unabsorbed dietary magnesium is excreted in the faeces; absorbed magnesium is excreted in urine and sweat.
Magnesium deficiency is more common than people realise because few people consume the recommended dietary intake. Only 1% of magnesium is found in the blood, making deficiency difficult to detect. Often there are no particular symptoms, but muscle tremors andcramps, fatigue, insomnia, a rapid heartbeat, high blood pressure and weakened bones may occur. Headaches may also be linked to low magnesium levels and there is evidence that magnesium supplementation may play a role in the prevention and treatment of migraine.
Magnesium deficiency is particularly common among menopausal women, or those who experience premenstrual syndrome (PMS) because hormonal changes can cause the body to excrete more magnesium than normal. Woman often find that supplementation can dramatically improve their symptoms. Other causes of deficiency include renal or gastrointestinal loss as well as alcoholism and prolonged use of diuretic drugs. Chronic deficiency is associated with metabolic syndrome, Type 2 diabetes, depression, irritable bowel and hypertension. There may also be an increased risk of kidney stones.
As far as supplements are concerned, magnesium citrate and magnesium chloride have greater bioavailability (ie are more easily absorbed) than the more common magnesium oxide form.
Overdose from dietary sources of magnesium alone is unlikely because excess magnesium in the blood is filtered out and excreted by the kidneys. It is sometimes a result of taking too much of a magnesium-containing antacid or laxative. The most common symptoms of overdose are nausea, vomiting, and diarrhoea; other symptoms include low blood pressure, confusion, slowed heart and respiratory rate, deficiencies of other minerals, cardiac arrhythmia, and kidney failure.
NB You should always seek professional advice before taking mineral supplements.