Summaries of the latest research concerning magnesium
By Hans R. Larsen MSc ChE
Magnesium is of key importance to human health. It participates in over 300 enzymatic reactions in the body. A deficiency has been linked to conditions such as irregular heart beat, asthma, emphysema, cardiovascular disease, high blood pressure, mitral valve prolapse, stroke and heart attack, diabetes, fibromyalgia, glaucoma, migraine, kidney stones, osteoporosis, and probably many more. Magnesium is particularly important when it comes to ensuring the health of the heart and bones. About 99% of the body's magnesium stores are found in the bones and tissues and heart tissue is particularly rich in this important mineral. About half of the body's magnesium stores can be found in bones, so it is clearly a very important mineral as far as osteoporosis prevention is concerned.Only 1% of the body's magnesium is actually present in the blood so a standard blood analysis is a very poor way of determining overall magnesium status.

The RDA (Recommended Dietary Allowance) is 420 mg/day for men and 320 mg/day for women. Unfortunately, recent surveys have shown that many Americans have a dietary intake of 200 mg/day or less. A recent study found that 74% of a cohort of 2000 elderly men and women did not consume the recommended amount. This same study also concluded that a high magnesium intake is associated with a significantly higher bone density in older white men and women. Every 100 mg/day extra intake of magnesium was found to correspond to a 2% increase in whole-body bone mass. This compares to an approximate 2% increase per 400-mg/day increase in calcium consumption. It is thought that magnesium may act as a buffer for the acid produced by the typical Western diet and may also replace calcium in the hydroxyapatite part of bone, thus resulting in a stronger structure. There is also evidence that magnesium suppresses bone resorption (demineralization) at least in younger people.Almonds, nuts, blackstrap molasses, wheat bran and wheat germ are good sources of magnesium; however, many people will, no doubt, prefer to take a magnesium supplement as an easy and reliable way of assuring an adequate daily intake. Up to 800 mg/day of elemental magnesium is probably safe; however, people with kidney disease or severe heart disease should not supplement with magnesium without their doctor's approval. There is some evidence that a continued magnesium deficiency may reduce the ability to absorb magnesium. Thus it may be necessary to have intravenous magnesium infusions first before an oral supplementation program can make a meaningful difference. Magnesium absorption tends to decrease as body stores are replenished so there is little chance of overdosing; nevertheless, patients with end-stage renal disease should not supplement with magnesium. Vitamin D is required for optimum absorption so it is important to get adequate unprotected sun exposure daily or to take a vitamin D-3 supplement when using oral replenishment of magnesium. Some magnesium supplements, when taken in excess, cause a looser stool and even diarrhea. Taking too much magnesium is not a good idea since diarrhea is likely to cause the loss of most, if not all, of the supplemented amount.The most common magnesium supplements are magnesium oxide, magnesium carbonate, chelated magnesium (magnesium glycinate), magnesium orotate, magnesium citrate, magnesium maleate and magnesium gluconate. These supplements provide different amounts of elemental magnesium (the constituent that matters) and also vary significantly in their bioavailability (absorption).Magnesium oxide is the most dense magnesium compound and the one most often used in mineral supplements and multivitamins. It contains 300 mg of elemental magnesium per 500 mg tablet, but is extremely poorly absorbed. Only about 4% of its elemental magnesium is absorbed or about 12 mg out of a 500 mg tablet.Magnesium carbonate contains 125 mg of elemental magnesium per 500 mg tablet, but is poorly absorbed.Chelated magnesium (magnesium glycinate) is magnesium bound in a complex of glycine and lysine. It is easily absorbed and highly bioavailable. The magnesium (elemental) content per tablet or capsule is usually 100 mg.Magnesium orotate contains only 31 mg of elemental magnesium per 500 mg tablet. However, it is well absorbed and has been found highly effective in daily intakes of 3000 mg (186 mg elemental).Magnesium citrate contains 80 mg of elemental magnesium per 500 mg tablet. It is far better absorbed than is magnesium oxide. The water soluble form (Natural Calm) contains 205 mg of elemental magnesium per teaspoon, is totally soluble in hot water and is highly bioavailable.Magnesium maleate contains 56 mg of elemental magnesium per 500 mg tablet.Magnesium gluconate contains 27 mg of elemental magnesium per 500 mg tablet. It is easily absorbed and quick acting.All forms of oral magnesium supplements are better absorbed when taken with a meal.