Magnesium Supplementation

By Shawna Kopchu RN and Herbert C. Mansmann Jr, M.D.

The recommended daily allowance for Magnesium is 6mg/kg/day. Most people need at least 100mg or as much as 600mg per day of supplemental magnesium, just to remain in Positive Magnesium Balance. Which means, one takes in more magnesium than one loses. This amount does not include the various diseases and medications that can cause you to lose Mg. If you are on any of the medications or have a disease that causes Urinary Mg Wasting then you need more than the RDA for Mg. To check the list Click Here (Need Link)

The chart in Table 1 below shows the RDA of Mg. This should be the absolute minimum amount that you should take.
A recent survey conducted by The Gallup Organization has found that 72 percent of adult Americans are falling short of the Recommended Dietary Allowance for magnesium.

The survey further revealed that 55 percent of all adults are consuming three-quarters or less of the RDA, while 30 percent are eating less than half the required amount of the mineral.

The survey also reported that magnesium consumption decreases as we age, with 79 percent of adults 55 and over reportedly eating below the RDA for magnesium, and 66 percent are getting less than three-quarters of their allowance from food.

A potential magnesium deficiency is a matter of concern for many individuals of all ages, but for the elderly, it could be particularly serious,” said Richard Rivlin, M.D., program director of the Clinical Nutrition Research Unit at Memorial Sloan-Kettering Cancer Center in New York, and chief of the Nutrition Division at New York Hospital-Cornell Medical Center

A separate Gallup survey of 500 adults with diabetes reported that 83 percent of those with diabetes are consuming insufficient magnesium from food, with many by significant margins. Sixty-eight percent of the men and 56 percent of the non-pregnant women said they were consuming three-quarters or less of their RDA for the mineral. “This is a concern,” said Susan Thom, a registered dietitian, “Since research has shown a strong association between magnesium and the body’s ability to use insulin properly.”

Insulin is a hormone required to convert glucose (sugar) into energy. But for diabetics, the body either does not manufacture sufficient amounts of the hormone or is unable to process it.

“In fact,” Thom continued, “a consensus panel convened by the American Diabetes Association has recommended that all persons with diabetes who are at high risk for high blood pressure be tested and, if a problem is found, treated with a magnesium chloride supplement.”

In spite of this recommendation, Thom added, only five percent of the diabetics polled were aware that magnesium deficiency is prevalent among diabetics.

And 99 percent – of whom more than half (53 percent) have a history of heart disease and/or are taking diuretics (water pills to induce urination) – said they had not been advised by a health care professional about a possible magnesium deficiency.

A magnesium deficiency in diabetics may result in an increased risk for cardiac arrhythmias, high blood pressure, myocardial infarction (heart attack) and altered glucose metabolism, according to Robert K. Rude, M.D., of the Southern California School of Medicine in Los Angeles, in the October 1992 issue of Postgraduate Medicine.

He added that a magnesium deficiency is associated with low blood levels of calcium and potassium.

Gastrointestinal loss and renal (kidney) wasting are other considerations warranting oral magnesium supplements, he said.

Table 1 The 1997 DRI’s for Magnesium, Calcium, Phosphorus, and Vitamin D


Mg-RDA (mg)

Ca-AI (mg)

P-RDA (mg)

Vitamin D-AI (ug)






















































*Above 1989 RDA; **Below 1989 RDA; ***Above 1989 but below 1980 RDA

are higher for Mg, than they were in the 1989 RDAs, but lower than in the 1980 RDAs for pregnant women. For Ca and P, the DRIs are lower than the RDAs for some but higher for others. Adult Ca intake is increased from 800 mg to 1000 mg for adults up to the age of 50 years, and further increased to 1200 mg for those older than 50. Adult DRIs for vitamin D are similar to the previous RDAs for young adults, but are higher for those older than 50. Ca and vitamin D recommendations for older adults were increased largely to prevent osteoporosis. ULs (Table II) were developed to provide guidelines for supplements and for nutritional fortification of foods.

Table II The tolerable upper limits (UL) for Magnesium, Calcium, Phosphorus, and Vitamin D





Vitamin D*






All ages





For Mg, UL is intake only from supplements; does not include Mg in food and water.

For Ca, P, and vitamin D, includes the total intake from food, water, and supplements.
How does Magnesium work for Migraines?

Magnesium is a dietary mineral that helps regulate blood vessel size, serotonin function, and nerve activity in the brain, among other functions. Magnesium deficiency is thought to be at least one important factor in migraine attacks. Many studies suggest that magnesium might be a common denominator in both the vascular and the neural theories of migraine. In support of the vascular theory, magnesium deficiency results in blood vessel constriction and adding magnesium to the diet leads to the opening (dilation) of blood vessels. In support of the neural theory, magnesium deficiency has been linked with the production and release of substance P12-a biochemical that contributes to the inflammation of nerves and headache pain.

In a recent study conducted by Dr Alexander Mauskop and his colleagues, they reported an 85% success rate in treating migraines with an intravenous injection of magnesium. In the study 85% of the magnesium deficient men and women in the middle of a migraine attack experienced rapid and dramatic relief of symptoms when they received magnesium. Within minutes individuals felt relief of migraine pain. They also felt relief from nausea and from sensitivity to light and noise. Aside from a very few patients who had short-term light headedness during the infusion, there were no side effects. In the study people who were not deficient in magnesium at the outset did not experience relief. This indicates that improvement was not due to a placebo effect.

Recent studies indicate that magnesium depletion, that is, having lower than normal levels of the mineral magnesium, can influence serotonin and nitric oxide release, blood vessel size, and inflammation. It’s also thought that people with mitral valve prolapse have lower than normal levels of magnesium.

Several studies have shown that magnesium depletion plays a critical role in blood vessel size. It seems not only to cause blood vessel constriction but to make blood vessels more sensitive to other chemicals that cause constriction and less sensitive to substances that cause blood vessels to dilate.

Studies have also shown that magnesium depletion seems to help release serotonin from its storage sites. It also helps make blood vessels in the brain more receptive to serotonin and thus clears the way for serotonin to cause constriction of blood vessels.

Replacing magnesium has been shown to have a very positive effect on migraine symptoms in some people.
How safe is Magnesium?

The Safety of Oral Magnesium Supplements

* The intestines control the amount of magnesium absorbed, since any overdosing with magnesium causes diarrhea, which expels the overdose. This is the way Milk of Magnesia works, resulting in evacuation of the entire bowel, because this salt is virtually insoluble and combines with water to act as a laxative. If you are taking Mg Supplements and take too much you will develop an episode of watery diarrhea that will last about an hour. You should then decrease your next dose by 50% as indicated on the Mg Dosing page. If you are on a Mg Supplement and have diarrhea that is accompanied by fever, abdominal cramping, blood or pus in the stool or black tarry stools this is not an indication of Mg excess and you should notify your doctor immediately to find the source of your diarrhea.
* As long as the kidneys are functioning adequately, the body cannot accumulate excess magnesium in the blood. This is best determined by doing a serum creatinine level. Those with higher than normal creatinine levels need to be evaluated medically and should not take Mg supplements without the direct supervision of their physician.
* The above two responses of the body protect us from an excess of Mg.
* Magnesium supplementations are safe during pregnancy but you should always consult your obstetrician before starting any medications or vitamin & mineral supplementation during pregnancy.

Will Magnesium interfere with my medications?

Drug Interactions

Allopurinol, antibiotics, digoxin, iron salts, pencillamine, phenothiazines: Decreased effect because of possible impaired absorption. Separate administration times by 1-2 hours.

The absorption of quinolone and tetracycline antibiotics as well as nitrofurantoin is diminished when taken with magnesium supplements. Therefore, magnesium should be taken two to four hours before or after taking these medications to avoid interference with absorption.

Enteric coated drugs: May be released prematurely in stomach. Separate doses by at least 1 hour.

Parenteral magnesium sulfate can enhance the neuromuscular blocking effects of neuromuscular blockers such as d-tubocurarine, and succinylcholine. Caution should be exercised when using these agents concurrently.

Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with barbiturates, opiate agonists, H1-blockers, antidepressants, benzodiazepines, general anesthetics, local anesthetics, and phenothiazines.

Concurrent use of oral magnesium salts with sodium polystyrene sulfonate (Kayexalate?) is not recommended. Sodium polystyrene sulfonate may bind with magnesium salts administered orally; however, the risk of binding with oral magnesium salts may be less with rectal administration of sodium polystyrene sulfonate.

Excessive ethanol or glucose intake has been found to increase urinary excretion of magnesium. Avoid high intakes of ethanol and glucose while taking magnesium salts.

Concurrent use of intravenous calcium salts with parenteral magnesium sulfate can neutralize the effects of parenteral MgSO4; however, calcium gluconate and calcium gluceptate are used clinically to antagonize the toxic effects of hypermagnesemia. Simultaneous use of parenteral magnesium sulfate and intravenous calcium salts is also used in patients with post-parathyroidectomy “hungry bones” syndrome or tetany associated with hypocalcemia and hypomagnesemia. Oral calcium-containing medications may increase serum calcium or magnesium concentrations in susceptible patients, primarily patients with renal insufficiency.

Administration of oral magnesium salts with cellulose sodium phosphate or edetate disodium (EDTA) may result in binding of magnesium. Do not administer oral magnesium salts within 1 hour of cellulose sodium phosphate or edetate disodium.

Concurrent use of cardiac glycosides with magnesium salts may inhibit absorption and possibly decrease plasma concentrations of cardiac glycosides. Because cardiac conduction changes and heart block may occur magnesium slats must be administered with extreme caution in digitalized patients, especially if intravenous calcium salts are also used.

Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of loop diuretics or thiazide diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia. Conversely, long-term use of potassium-sparing diuretics has been found to increase renal tubular reabsorption of magnesium which may cause hypermagnesemia in patients also receiving magnesium supplements, especially in patients with renal insufficiency.

Concurrent use of magnesium supplements with other magnesium-containing antacids or laxatives may result in magnesium toxicity, especially in patients with renal impairment.

Administration of oral magnesium salts with oral tetracyclines or quinolone antibiotics may form nonabsorbable complexes resulting in decreased absorption of tetracyclines and quinolones. Do not administer oral magnesium salts within 1?3 hours of taking an oral tetracycline or oral fluoroquinolone.

Oral magnesium salts may prevent absorption of oral etidronate. Do not administer magnesium salts within 2 hours of oral etidronate.

Clinically significant drug interactions have occured when IV magnesium salts were given concurrently with nifedipine during the treatment of hypertension or premature labor during pregnancy. The women affected presented with either pronounced muscle weakness and/or hypotension. In a few cases, fetal harm was noted as a result of the hypotensive episodes. The effects have been attributed to nifedipine potentiation of the neuromuscular blocking effects of magnesium. It is recommended that nifedipine not be given concurrently with magnesium therapy for pre-eclampsia, hypertension, or tocolytic treatment during pregnancy.

Magnesium-containing antacids and supplemental magnesium salts should not be used in patients receiving vitamin D analogs. Vitamin D analogs can increase serum magnesium concentrations in patients with chronic renal failure.
Does Magnesium have any side effects?

Important Overdose Symptoms to Recognize

  • Diarrhea is the most common symptom of magnesium overdose, but it is important to remember that diarrhea could be due to an acute viral illness or sorbitol found in many diet foods and candy. It also could be due to dietary indiscretion such as in the case of a known food allergy or intolerance.
  • At serum magnesium levels between 3 mEq and 5 mEq/liter, there is a tendency for lowered blood pressure because of peripheral vasodilation. (Severe hypotension may occur at higher levels.) Facial flushing is sometimes seen, associated with sensations of warmth and thirst. While nausea and vomiting may occur, they are not always present.
  • When serum magnesium levels reach 5 mEq to 7 mEq/liter, lethargy, dysarthria, and drowsiness can appear. Deep tendon reflexes are lost when the serum magnesium level increases to about 7 mEq/liter.
  • The respiratory center becomes depressed when serum magnesium levels exceed 10 mEq/liter; expected changes include shallow respirations, irregular brief periods of apnea and, finally prolonged apnea.
  • Coma occurs when the serum magnesium concentration is 12 mEq to 15 mEq/liter. Cardiac arrest may be expected when the serum level exceeds 15 mEq to 20 mEq/liter.
  • It is possible to produce an overload of any electrolyte if excessive quantities are administered; magnesium is no exception. For example, excessive magnesium administration during treatment for eclampsia can cause both maternal and fetal hypermagnesemia. For this reason, magnesium should be administered cautiously, especially to patients with decreased renal function. While normal persons can excrete 40g to 60g of administered magnesium per 24 hours and thus safely receive large doses of magnesium, those with decreased renal function cannot.

What dose of Magnesium should I take?

Since the majority of us do not eat right nor do we have the perfect stress-free life, we will need to take more than the RDA for Mg, because we need to take in more than we lose. Herbert C. Mansmann, Jr., M.D., Director of The Magnesium Research Laboratory at Thomas Jefferson University in Philadelphia, PA has come up with a dosing method that really works great. Dr Mansmann has done research on the use of magnesium for the past 11 years. His method of dosing is a little different than what you are used to. But if you follow the directions you will get better!

  • First you must choose a Magnesium Product to use as a maintenance daily dose. This can be the magnesium product of your choice. You can check the magnesium product page for more detailed information about the different products. The most commonly prescribed magnesium supplement is Magnesium Oxide. Magnesium Oxide comes in strengths of 250mg, and 400mg. Mag Tab SR is one magnesium supplement that is available that is sustained released. Mag Tab SR comes in one strength of 84mg/tablet. Slow Mag comes in one strength of 64mg/tablet and also has calcium 128mg/tablet. Slow mag is Magnesium Chloride and is enteric coated to prevent release in the stomach and decrease GI Upset.
  • Once you have decided on what product to take you will start out day 1 by taking the RDA. See the example below:

Example 1
Jill* is a migraineur who has decided to take Magnesium to help with her migraines. She is 160 pounds. The RDA is 6mg/Kg. To convert pounds to kg you divide the weight in pounds by 2.2 which will give you the Kg. 160 divided by 2.2 = 72kg. 72kg x 6mg = 432mg which is the RDA for Jill. So on day 1 Jill would take 1 Mag Oxide 400mg or 5 Mag Tabs or 7 Slow Mag’s. You can take these in divided doses. So she could take 2 Mag Tabs in the am, 1 at Lunch time and 2 at night. Any of the above combinations would give her the RDA for Mg.

  • Swallow tablets whole with a full glass of water.
  • Take the Mag Oxide, Slow Mag and Mag Tab SR with food.
  • When taking the Mag Tab SR – scored tablets may be broken without affecting the 12hr sustained release.
  • Slow-Mag is enteric coated and tablets should not be broken.

When and how should I increase the dose?

If you are still having symptoms (Migraines, leg cramps, ect) and you have a constipated bowel movement increase the next dose by one tablet.

Example 2

Jill is taking her above maintenance dose of 5 tablets of Mag Tab Sr. She develops a migraine on day 3 and also has noticed lately that her stools have become less frequent. Jill would then increase her dose to 6 tablets/day and continue to increase it each day as long as she was still having constipation and migraines. If Jill was taking the Mag Oxide she could also try taking one Mag Tab since it is sustained released and would give her 7mg/hour of Mg. You can mix the above salts.

* An increase of the magnesium dose is taken when a new medication known to cause an increase in urinary magnesium excretion causes symptoms. (Check the Urinary Magnesium Wasting Page for a list of drugs that can cause urinary magnesium wasting. If you are on any of them and your symptoms return then that would be an indication to increase your next Mg dose).
* An increase in disease specific conditions that cause changes in magnesium metabolism; hyperglycemia documented by self monitoring of blood sugar, an obvious increase in stress, ect.
* With the above symptoms the maintenance dose should be increased by 25%.

Example 3

Jill is taking her maintenance dose of 432 Mg per day. She gets a sore throat and her doctor puts her on Zithromax which is a drug that is known to cause Urinary Mg wasting. She would then increase her maintenance dose by 25% which is 432 x25=108mg. So her maintenance dose would then be 432+108=540mg. So if she was taking the Mag Tab SR her maintenance dose would now be 6 tablets per day.

When and how should I decrease the dose?

* With watery diarrhea decrease the dose by 50%, since this is usually short lived, if present at the time of the next maintenance dose repeat the above lower dose. Then try to control symptoms with a 25% lower dose.

Example 4:

Jill is taking her maintenance dose of 540mg when she suddenly has an episode of diarrhea. Jill’s next dose is due at lunchtime. So at lunch time she will take 50% which would be 270mg. For her evening dose she would then decrease her maintenance dose to 432 mg which is 25% less than her normal dose.

* When a very soft bowel movement occurs, decrease the next dose by 25%. May need to alternate doses regularly, such as 75% and 100% of maximum tolerated dose.

Example 5:

Jill is taking her maintenance dose of 540mg when she has a very soft stool (Almost diarrhea like). Jill’s next dose is due at lunchtime. So at lunch time she will take 75% which would be 432mg. For her evening dose she would then decrease her maintenance dose to 432 mg which is 25% less than her normal dose. If her migraines come back she may need to increase back up to the 540mg.

* Comfortably soft bowel movements are desirably objective and should be considered optimal.

How to use Magonate

Magonate© is a magnesium supplement sold by Fleming Co. It is Magnesium Gluconate, calcium and phosphorus. You can use any brand of Magnesium gluconate to achieve the same results. Magnesium Gluconate enters the cell very rapidly and is used up within an hour. So it is not good for a maintenance product because it is used up too quickly and also only comes in 27mg tablets which means you would have to take about 20 tablets a day just to get the RDA. For more information on Magonate or any of the Magnesium Supplements please visit the Magnesium Product page.

Magonate should be used when you feel acute symptoms coming on. For example if you are taking it for migraine prevention then you would take 5 magonate tablets at the first sign of migraine aura or pain. If you are taking it for leg cramps you would take 5 tablets at the first sign of leg pain. You can repeat the 5 tablets in one hour if your symptoms are not better. You can repeat the 5 tablets every hour until you get relief. I limit my dose to 20 tablets because of the calcium in it. Since I take calcium supplements also. Usually you will see a significant improvement after the second dose.

You can take the Magonate in addition to your daily maintenance. If you find you are using the Magonate all the time then you should increase your daily maintenance dose.

* Take the Mg Gluconate (Magonate) on an empty stomach. 1hr before or 2hrs after a meal.

Example 1:

Jill is taking Mag Tab SR for her migraines. Her daily maintenance dose is 6 tablets per day or 504mg per day. Now she has been on her supplements for about a month without a problem. She starts to develop an aura at 1:00pm and knows the migraine is soon to follow. So she would take 5 Magonate tablets at 1:00pm. At 2pm she starts to feel the migraine starting. So at 2pm she takes another 5 Magonate tablets. At 3pm she still doesnt feel right so she should take 5 more Magonate tablets. At 3:45pm she starts to feel relief. The next day the aura starts again. She takes 5 Magonate tablets and this time she ups her daily maintenance to 7 tablets – because she is getting breakthrough symptoms this is a sign that her daily maintenance is not enough.

Example 2:

Jill is taking her daily maintenance dose of Magnesium – 6 tablets. She notices at 2pm that she missed her noon dose. To prevent getting symptoms from missing her dose she can take her noon dose now and also take 5 Magonate tablets. This way she gets instant relief that can work quickly and hold her over until her normal noon maintenance dose kicks in. Since it takes about 2-3 hours for the Mag Tab to start working she may need to repeat the Magonate dose for 2-3 hours until the Mag Tab starts working.
Should I take anything with the Magnesium?

Calcium – Anyone who takes a magnesium supplement should also take calcium. The ratio is 2:1 calcium to Magnesium up to a maximum of 2 grams of calcium per day. So if your daily maintenance dose of Magnesium is 600mg per day you would take 1200mg of calcium. If you take 1,000mg of Mg then you would take 2,000mg of calcium. If you take 2,000mg of magnesium you would only take 2000mg of calcium since that is the maximum that your body needs. If you take more calcium than 2 grams your body will not use the excess and it could compete with the Mg and actually cause your Mg to drop.

* Riboflavin – Researchers have found that taking high doses of Riboflavin (400mg/day) along with the magnesium helps alleviate migraines.
* Vitamin B6 – helps with magnesium absorption.


Garrison Jr RH, Somer E. The Nutrition Desk Reference. 3rd ed. New Canaan, Conn: Keats Publishing Inc; 1995:158?165.

Neuvonen PJ, Kivisto KT. Enhancement of drug absorption by antacids. An unrecognized drug interaction. Clin Pharmacokinet. 1994;27(2):120-128.

Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs. 1976;11(1):45-54.

Nutrients and Nutritional Agents. In: Kastrup EK, Hines Burnham T, Short RM, et al, eds. Drug Facts and Comparisons. St. Louis, Mo: Facts and Comparisons; 2000:4-5.

Print This Post Print This Post