有此一说，转一篇英文文章，另外现在的葡萄糖酸钙也有含镁的

Magnesium has been used widely for clinical manifestation of muscle cramps, with good success. Research has shown that it is not just deficient individuals that benefit from supplementation, rather it has been hypothesized that everyone can benefit from its ability to stabilise cellular membranes. Magnesium is critical to cellular functioning in terms of energy production, cell reproduction, and protein formation. It is essential for energy production. Magnesium also is pivotal to maintain control of the sodium and potassium pump.

Defining a cramp is simple enough: It's nothing more than the short, involuntary contraction of a muscle. One of your muscles literally decides to flex, and to briefly stay that way, without your permission.
Low levels of certain minerals known as electrolytes-magnesium, potassium, calcium and sodium-have long been linked to leg cramps. (Marathon runners sweating out the miles are particularly prone to this variety.) Certain drugs, such as diuretics (water pills) for the heart and for high blood pressure, have also been cited as a cause of leg cramps. Dialysis patients, who have their blood filtered by a machine because their kidneys don't work properly, often complain of leg cramps. And pregnancy, it seems, is also a factor.

Food Factors
- These dietary tips can help you keep magnesium and vitamin E, the nutrients that help ward off leg cramps, where you need them: in your body.
- Cut the cocktails. Even a single drink containing alcohol may decrease the supply of magnesium in your body, says Lorraine Brilla, Ph.D., associate professor of exercise physiology at Western Washington University in Bellingham.
- Trim the fat. Dietary fat makes magnesium harder to absorb, increasing the chances that it will be wasted, Dr. Brilla says.
- Cap your sweet tooth. Eating sugary foods forces your body to use magnesium just to metabolize the sweet stuff, adds Dr. Brilla.
- Can the cola. Soft drinks contain phosphates, which experts say also deplete your body of magnesium and calcium.

Making a Case for Magnesium
You've seen those sports drink ads on television, the ones featuring weary, sweat-soaked weekend warriors gulping bottles of fluid filled with electrolytes. Electrolytes - magnesium, potassium, calcium and sodium - are some of the most important and most well known nutrients in the fight against cramping. What most folks don't know, however, is that you're likely to run out of magnesium before any other electrolyte.
"The truth is, most people in this country just don't eat enough foods containing magnesium," says Robert McLean, M.D., clinical assistant professor of medicine at Yale University School of Medicine and an internist in New Haven, Connecticut. And even if you do eat plenty of green, leafy vegetables and other foods rich of magnesium (such as nuts, figs and pumpkin seeds), there are many things that rob your body of this important nutrient. Certain medications used to treat heart disease and high blood pressure, for example, flush magnesium from the body.
So what's the connection between magnesium and muscle cramps? Think of a key and a lock. Normally stored in muscle and bone, magnesium acts like a key that unlocks muscle cells, allowing potassium and calcium to move in and out when needed as a muscle does its job.
Without adequate levels of any of these three nutrients, the muscle becomes irritable, says Dr. McLean. "It's a crude analogy, but to keep the muscle cell adequately healthy and alive, you need to get potassium into the cell, and you need to have magnesium to open up the door to let the potassium in," he explains.
Make no mistake: Both potassium and calcium are also vital to this process. It's just that the body generally has adequate amounts of these two electrolytes on hand, says Dr. Brilla. If the body is going to get low on any electrolyte, it is most likely to be magnesium, she says. Doctors have long marveled at magnesium's powerful relaxant effect on muscles. In massive intravenous doses, this mineral is the preferred treatment for stopping premature labor contractions and a dangerous condition called preeclampsia, which causes extreme swelling and high blood pressure in pregnant women. (Note: Pregnant women should not take any supplement without first discussing it with their doctors.)
Before recommending magnesium supplements to ease muscle cramps, Dr. McLean does a blood test to determine an individual's blood magnesium level, to make sure that it is not unexpectedly high. If the blood level is low or even normal, then body magnesium stores may be low. Unfortunately, a normal blood level does not ensure that body magnesium stores are adequate.
Based on the results of the tests as well as the person's muscle cramp symptoms, Dr. McLean usually recommends taking one 400-milligram magnesium capsule two or three times a day. "I wouldn't go higher than that, because too much magnesium can cause you to develop diarrhea," he says. (Magnesium salt is the ingredient that makes Phillips' Milk of Magnesia, a popular bowel cleanser, do its job.)
But be careful: If you have kidney problems, taking magnesium supplements may make you accumulate the mineral too quickly, which could be toxic, says Dr. McLean. If you have kidney or heart problems, you should check with your doctor before taking magnesium supplements. Some people taking magnesium may get relief from leg cramps right away, but a long-standing deficiency can take weeks to overcome with supplements, says Dr. Brilla. "We like to recommend supplementing for four weeks," she says. "That's how long we feel it takes before we have some kind of measurable outcome."

Magnesium - a natural remedy for muscle cramps
Canadian doctors have found that magnesium supplements can alleviate muscle cramps. In severe cases, magnesium has been provided intravenously and this has led to relief of symptoms within 24 hours. Many cases of muscle cramps are caused by low concentrations of magnesium in the blood which can be the reason why it helps is be due to diuretic medications or strenuous exercise. When taken orally, it seems that magnesium glucoheptonate or magnesium gluconate work best.

Magnesium and pregnancy-induced leg cramps - adapted from the American Journal of Obstetrics and Gynecology
It has been suggested that a secondary deficiency of magnesium may be responsible for the leg cramps experienced by as many as 30% of pregnant women. Magnesium therapy has been shown to be of value in the treatment of other types of leg cramps in elderly patients and diabetics, and results of a preliminary open trial have suggested that it may help during pregnancy. This controlled study was designed to evaluate the effects of magnesium supplementation on pregnancy-related leg cramps.
Researchers from two hospitals in Sweden conducted a double-blind, randomized trial in which 73 women with pregnancy-related leg cramps were randomly assigned to receive oral magnesium (15 mmol) or placebo daily for three weeks. Serum magnesium levels were measured, and patients recorded the frequency and severity of their leg cramp symptoms before and after treatment. Magnesium supplementation significantly decreased the severity of leg cramps, but it did not have a significant impact on serum magnesium levels. Side effects were insignificant. The results of this trial indicate that oral magnesium supplementation may be a valuable treatment option in the management of pregnancy-induced leg cramps.

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• 谢谢补充信息 -欲千北- ♂ (0 bytes) () 09/30/2010 postreply 13:41:49