I'm very interested in this subject, and went to find the government's Recommended Daily Allowance (see below.) I don't believe everything I read, but this is from Whole Foods website and WholeHealth MD:Magnesium * What Is It? * Health Benefits * Forms * Recommended Intake * If You Get Too Little * If You Get Too Much * General Dosage Information * Guidelines for Use * General Interaction * Possible Side Effects * CautionsWhat Is It?Essential for hundreds of chemical reactions that occur in the body every second, the mineral magnesium has received surprisingly little attention over the years. Recent findings, however, suggest that it also has important health-promoting benefits, from an ability to prevent heart disease to a role in treating such chronic conditions as fibromylagia and diabetes.Unfortunately, most people don't get enough magnesium in their daily diets, mainly because they eat great quantities of processed foods, which provide scant amounts of this important mineral. The effects of stress, intense physical activity, or the use of certain medications can also cause magnesium deficiency. Some diseases, such as diabetes and alcoholism, can cause low magnesium levels too.Supplements are one way to ensure that you get enough magnesium. You'll find several forms available: magnesium citrate, magnesium aspartate, magnesium carbonate, magnesium gluconate, magnesium oxide, and magnesium sulfate.Health BenefitsMagnesium plays a variety of roles in the body. Not only is it critical for energy production and proper nerve function, it also promotes muscle relaxation and helps the body produce and use insulin. Like calcium, another mineral it's commonly paired with in supplement products, magnesium is involved in the formation of bones and teeth, the clotting of blood, and the regulation of heart rhythm. Magnesium, sometimes taken in combination with calcium, is often used to treat such ailments as back pain, high blood pressure, depression, anxiety and panic, muscle cramps, and migraine headache.Prevent osteoporosis. Magnesium helps the body convert vitamin D�which the body needs to take advantage of bone-strengthening calcium�into a form that it can use efficiently. By contributing to increased bone density, the mineral may help stall the onset of the debilitating, bone-thinning disease known as osteoporosis.Note: Magnesium has also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Magnesium.Forms * tablet * powder * capsuleRecommended IntakeThe government recently established new goals for the Recommended Daily Intake of magnesium for men and women. The Recommended Dietary Allowance (RDA) is now just one component of the new calculations, but is still the figure most important in trying to establish how much you need. The new RDAs are as follows for magnesium: * For men ages 19 to 30: 400 mg a day. * For women ages 19 to 30: 310 mg a day. * For men ages 31 to 50: 420 mg a day. * For women ages 31 to 50: 320 mg a day. * For men ages 51 to 70: 420 mg a day. * For women ages 51 to 70: 320 mg a day.For more information on RDAs and other dietary guidelines, see Government Dietary Guidelines.If You Get Too LittleLow levels of magnesium can increase your risk for complications of heart disease and diabetes. You may also be more susceptible to muscle cramps, various chronic pain conditions, and muscle fatigue. Symptoms of a severe deficiency include irregular heartbeat, general fatigue, muscle spasms, irritability, nervousness, and confusion.If You Get Too MuchDiarrhea and nausea are the most common side effects of ingesting too much magnesium. If the body is unable to process particularly high doses of magnesium, muscle weakness, lethargy, confusion, and difficulty breathing may develop. Serious overdose of this mineral is rare.General Dosage InformationSpecial tip: * When selecting a magnesium product, try magnesium citrate first; it's the form that the body absorbs best. Magnesium oxide is often the cheapest form available, but it's also the most poorly absorbed.For heart disease prevention: Take 400 mg of magnesium a day.For angina prevention: Take 200 mg twice a day.For arrythmias, congestive heart failure, and asthma: Take 400 mg twice a day.Be sure to check out our Dosage Recommendations Chart for Magnesium, which lists therapeutic dosages for specific ailments at a glance.Guidelines for UseTo enhance absorption, take magnesium supplements with food. If you happen to consume a high-fiber diet and also don't get much magnesium, however, take the supplements between meals--and not with soda or wheat bran. These contain substances (phosphoric acid and phytates, respectively) that can interfere with the absorption of the magnesium.If diarrhea develops with magnesium supplements, either reduce the dose or take magnesium in the form of magnesium gluconate or magnesium sulfate. Both of these forms are easy to digest.When calculating your daily dose, keep in mind that some prescription and over-the-counter medicines--certain antacid products, for example--contain magnesium as well.When taking magnesium to control asthma, fibromyalgia, heart disease, or other chronic conditions in particular, be patient. It may take six weeks or more to absorb adequate amounts of magnesium to benefit stressed body parts and notice a difference in your condition.Muscle cramps, aches, and pains related to sports injuries are best treated with a regimen that supplies two parts calcium to one part magnesium.When taking magnesium to protect against migraines, first correct any magnesium deficiency and then take a 2-to-1 calcium-magnesium combination to maintain a healthy balance of these two minerals and protect against future headaches.To most effectively relieve PMS pain, it's usually a good idea to take magnesium along with vitamin B6.General InteractionsMagnesium and calcium have competing effects on many of the body's chemical pathways. For this reason, combination magnesium and calcium products—or multimineral supplements—are often recommended for maintaining a proper balance of these minerals.Magnesium can reduce the effectiveness of tetracycline antibiotics. Take magnesium supplements one to three hours before or after using this type of medication.Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.CautionsIf you have any type of kidney or heart disease, consult your doctor before taking magnesium.Ailments DosageConstipation 400�800 mg a day as neededDisclaimer: All material provided in the WholeHealthMD Reference Library is provided for educational purposes only. Consult your own physician regarding the applicability of any opinions or recommendations with respect to your symptoms or medical condition.Home : Health Info : Supplements : Magnesium