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Info on magnesium by Herbert Mansmann MD

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Jefferson Medical College
Thomas Jefferson University

HERBERT C. MANSMANN, Jr., M.D.* Director
1025 Walnut Street College Building, Suite 702A
Philadelphia, PA.,19107-5083

REVISED 8/2/01



1. The Recommended Daily Allowance (RDA) for Mg is between 350 and 450 milligrams (mg) - (6mg per kg per day). One pound of spinach and its cooking water a day will meet this requirement for a normal adult. Green vegetables with their chlorophyll, which contains Mg are good choices, as are nuts, legumes, unpolished rice, and whole grains. But the American diet contains too many refined ingredients. If you are pregnant or ill 600 mg of Mg/day - (10 mg/kg/day), is usually required.

2. The diet of high-income American women contains 120 mg of Mg per 1,000 calories. (Am Col Nutr 1993;12:444). Who today eats 3,000 to 4,500 calories per day in America? If you diet how much Mg do you get per day?

3. Chronic diarrhea is a common cause of Mg deficiency (MgD) and constipation is a common symptom of MgD.

4. Studies have shown that only 25% of Americans receive the RDA of Mg in their diet and 39% get less than 70% of the RDA.

5. Therefore, most healthy Americans need at least 350 mg or as much as 600 mg per day of supplemental elemental Mg, just to remain in positive Mg balance (PMgB). Which means, one takes in and absorbs more Mg than one loses in the urine. Unfortunately, many have other causes of negative Mg balance (NMgB), commonly called and resulting in MgD.

6. If one tolerates 1,000 or more mg of Mg per day and has a normal serum Mg (sMg) level, that person must have at least the mildest form of MgD, an intracellular MgD. This is referred to as normomagnesemia MgD, a very frequent event, the part below the tip of an iceberg. Only 10-20% of those with MgD have a low sMg level, the only test of MgD, many doctors recognize and/or ever test. The other 80-90% with normal sMg, need tests for intracellular Mg content, or for Mg wasting.


Many of the causes of MgD are due to more than one of the following mechanisms. This is a very complicated situation, for example: Neurontin binds Mg in the GI tract and results in a malabsorption of both oral Mg and Neurontin (PDR says 24%). While the Company claims to have no information on Neurontin binding of Mg in the blood, clinical experience has shown that sMg levels must be lowered causing symptoms of MgD. While maybe not causing low sMg levels, per se, this drug does cause hypertension due to catecholamine (adrenalin type hormones) release (a known cause of redistribution of Mg) and hyperglycemia (an increase in blood sugar) both of which result in sMg loss by redistribution and/or by an increased urinary Mg wasting (uMg). Thus this very important medication can cause MgD through three of the four mechanisms listed below.

1. Oral intake problems such as dieting, starvation, intravenous and tube feeding, eating Mg poor American foods, vomiting, etc.

2. Malabsorption for example chronic diarrhea, and many other intestinal problems. Two cans of soda per day, (all of which contain phosphates), bind and prevent absorption of Mg ions from the GI tract. This is worse if one takes an Aspartame containing sodas, because in the GI tract the Mg binds Aspartame, which it does in the test tube in our laboratory. (If any Aspartame is also absorbed, say, after a large oral dose, it then would bind more ionized blood Mg, which is excreted in the urine). (Migraine is frequently caused by Aspartame in sensitive persons, a disease frequently helped by oral Mg supplementations and/or intravenous Mg sulfate {MgSO4}).

3. Redistribution in the body of Mg follows 2 oz. of Alcohol, 2 cups of coffee/tea, or hot chocolate per day and the use of nicotine. Caffeinated diet soda is thus a triple problem. In diabetes, the intermittent high blood glucose seen in this disease enters many cells and displaces the Mg into the serum, which is then rapidly excreted in the urine. In stress catecholamines are released into the serum. Free fatty acids are then released that bind Mg, which is then stored in the tissues. Catecholamines also cause uMg wasting. The net effect is the loss of ionized Mg from the circulation. Ionized Mg is there to protect vital biochemical functions, and it is a co-factor in over 300 enzyme systems and their actions, including the CYP45O enzymes, which metabolize many toxins and drugs. Many drugs cause hyperglycemia, (the release of glucose into the serum), and many others cause the release of catecholamines and as mentioned above some medications do both.

4. Increased urinary Mg wasting occurs in association with binding of many drugs. In drugs used for asthma, and epilepsy, and some antibiotics, steroids, etc. bind with Mg, and some cause the release of high levels of glucose (sugar), and catecholamines. Adrenaline is one type of catecholamine, which is released as a side effect of many drugs, including some pain medications, anti-cancer drugs and anti-convulsants.

In addition, certain genetic kidney tubular diseases with limited reabsorption ability, such as Bartter’s and Gitelman’s syndrome and Distal Renal Tubular Acidosis, among others, result in uMg wasting. The rest of the kidney functions well, but the reabsorption defects involving Mg, calcium, potassium, and zinc vary in degrees and consequences. A 24 hr urine Mg content is an important diagnostic test.

Any human can develop MgD, if two or more of the above causes are present frequently enough. Each day's loss of Mg needs to be made up eventually by oral Mg intake, to remain healthy in PMgB. The bones, which contain 50% of the total body Mg, can keep our sMg levels normal for a long time. But this is just like money in the bank and continued uMg loss will ultimately break the bank, ending in osteoporosis, while the sMg falls. Thus, a low sMg, called hypomagnesemia, means one has a serious MgD. A low red blood cell Mg (rbcMg), is often found with a normal sMg. In addition, a low rbcMg is most likely seen when there is also a low sMg. Yet, a low rbcMg alone, is abnormal and an obvious excellent test showing intracellular MgD, although it is a less severe stage of MgD than a low sMg. However it is important to remember that total body MgD may be present when both the sMg and the RBCMg are normal, yet can be proven by doing a Mg Load Test.


1. Because of the tendency to diet, the occurrence of pregnancy and lactation (nature gives the mother's Mg, preferentially to infants), and the slow recovery of the Mg storage sites in the bones, women frequently develop MgD.

2. The following, sequential conditions in a female's life are associated with MgD: amenorrhea (absence of menses), oligomenorrhea (markedly diminished menses) which is often seen in athletes, premenstrual syndrome (PMS), menstruation, premature labor, preeclampsia, eclampsia, lactation, and postmenopausal osteoporosis, (shown to be associated with a past history of PMS-see Lee. Bone & Mineral, 1994:24(2); 127-34).

Women who had irregular menstrual bleeding duration had a 40% increased risk of hip fracture and women with both irregular menstrual cycles and irregular menstrual bleeding had an 82% increased risk of hip fracture compared with women who reported neither irregularity (Folsom, AR. Am J Epidemiol 2001;153:251-255).

3. Some of the following are possible consequences of maternal MgD; miscarriage, pre-term labor, premature babies have many MgD related problems and this probably includes apnea, the onset of cerebral palsy, stillbirth, sudden infant death in utero, and sudden infant death.

4. The following conditions, which are associated with MgD, occur statistically and significantly more frequently in females as compared to males; Alzheimer's disease, Carpel Tunnel Syndrome, competitive swimmers symptoms of MgD, diabetes, heart disease (worse types), migraine, Mitral Valve Prolapse Syndrome, osteoporosis and Status Asthmaticus (life-threatening asthma).

5. These women, as well as everyone, must try to maintain orally NATURE'S BALANCE, which is a calcium (Ca) to Mg intake ratio of 2 to 1. Even when one is taking medications for osteoporosis Mg is needed for the matrix of the bones and gives bones their tensile strength, while calcium gives bones it's hardness. Those with MgD will often need a larger amount of Mg than Ca. See the Topic on Mg, Ca and Osteoporosis in the patient information page on our web site.


1. Chronic constipation, hair loss, high blood pressure, kidney stones, migraine and/or some types of heart disease may be symptoms of MgD.

2. Neuromuscular symptoms of MgD are prominent. They may include nystagmus and thigh muscle and/or lower leg and toe muscle soreness, pain and cramps, as well as dysphasia (painful swallowing), fasciculations, (involuntary movements under the skin, inside of the muscles, which feels like something crawling under the skin), tremors and unsteadiness. There may also be numbness and/or tingling of the fingers and/or toes in some patients.

3. Nervous symptoms may be present in some patients and include anxiety, apathy, confusion, depression, difficulty concentrating and/or remembering and fatigue. The neuropathic pain called burning feet, (erythromelalgia), is associated with MgD in 30-50% of cases.

4. Ca is deposited, in the absence of sufficient Mg, in the drainage tubes of the kidneys to cause kidney stones. Ca can also be deposited in the soft tissue of the kidney, resulting in nephrocalcinosis when there is MgD.

5. Many have several symptoms at the same time. Those on Mg show a sequence of symptoms from the time for the next dose: 1st hour, the feeling of wearing boots and/or gloves, due to histamine release. 2nd hour, burning pain, in some with erythromelalgia due to Substance P release in MgD. and muscle cramps, spasms, or pain. 3rd hour. fasciculations. 4th hour, trouble swallowing. Migraine, PMS, and muscle cramps are often acute, while hair loss and other are slow to be manifested. One needs to observe oneself, to see when more Mg is needed to prevent symptoms due to MgD.

NOTE: One (1) gram of the various magnesium salts listed below contains the following amounts of elemental magnesium. Be sure to remember the amount of elemental Mg you are taking, which is found in your Mg salt. All of these Mg salts are over the counter (OTC) products, although the brand may not be stocked in all stores, so check with the pharmist to learn if it is behind the counter or can be ordered. We recommend the three below that are bold.

· magnesium chloride (MgCl): 120 mg (9.8 mEq) elemental magnesium.

· magnesium gluconate (MgG): 54 mg (4.4 mEq) elemental magnesium.

· magnesium lactate (MgL): 120 mg (9.8 mEq) elemental magnesium.

· magnesium oxide (MgO): 603 mg (49.6 mEq) elemental magnesium.

· magnesium sulfate (MgSO4): 99 mg (8.1 mEq) elemental magnesium.

MAGNESIUM OXIDE is an intermediate acting salt. (We have assayed Blaine and Co. and General Nutrition Center (GNC) products and found them to be accurate as stated. Other brands are available).

It is obvious from the above table that Mg oxide (MgO) is the workhorse because it contains the highest concentration of Mg. That is its major advantage, but it might be too much for some patients. A disadvantage is that it takes about 2 hours for any to be found in the urine. This is the only sign of absorption of Mg for those with normal sMg levels, which is also the amount of time it takes to see any clinical effectiveness to be seen. The MgO peak effect is in 4 hours, and gradually decreases in a few hours. Even with very high doses the kidneys will only maintain your sMg levels in the normal range, since Mg is stored in the bones not the serum.. If one's sMg is below normal, the sMg level will ultimately increase to the normal range. Thus between 0 and 2 hours, and between 4 and 8 hours the patient may need a higher dose to prevent symptoms of MgD.

MAGONATE is a rapid acting salt. (A Mg Gluconate (MgG) salt made by Fleming and Company Pharmaceutical; our laboratory assay has found the content to be accurately stated).

MgG is well tolerated, which is very important when taking any Mg product for the first time. Your druggist will usually have to order it. It takes only one day and does not require a prescription. Order 3 bottles of 100 tablets, which is enough for 2-4 weeks, a minimum trial. Each 500 mg tablet contains 27 mg of Mg*, and 5 tablets equal 135 mg of Mg. It is very rapidly absorbed, and the peak effect occurs in less than an hour when taken on an empty stomach. This Mg salt enters the blood and then the cells through the glucose pathways. This salt then dissociates in the cells to free gluconate and functional free ionized Mg. (FDA PB-288 p675 and p537) This Mg salt is an excellent RESCUE product, because five to ten tablets often relieves sudden unexpected acute symptoms and can be repeated as soon as one hour later without resulting in diarrhea. It has been shown that IV MgSO4 relieves Migraine (Mauskop, Headache. 1996:36;154-160) and Magonate by mouth does the same thing. Some of the daily dose of this salt is best taken at bedtime, because it results in a rapid sound sleep due to muscular relaxation.

* Since this product contains 89 mg Calcium as Ca Phosphate, a poorly absorbed salt, and no vitamin D (which facilitated Ca absorption), be sure to count at least half of the amount of Ca taken from these pills in your daily Ca allowance.

Mag Tab SR is a delayed acting salt. (This Mg salt is made by Niche Pharmaceutical Inc., 800-677-0355.

Mag Tab SR is 84 mg (7 mEq) of Mg from Mg L-lactate (MgL) in caplets containing a sustained release wax matrix formulation of this dehydrated compound. This formulation has the theoretical advantage that Mg is absorbed in small increments, 7 mg/hour for 12 hours as the matrix moves through out the bowel. It has been shown that lactate is excreted in the urine after taking MgL, which means that it is mostly absorbed intact leaving little or no Mg in the bowel to bind with 300 times it's weight of water, thus less likely resulting in loose stools.

More Than One Salt at a Time In certain situations all three of these Mg salts: an immediate, an intermediated, and the delayed acting Mg salts, may be necessary to reach one's maximum tolerated dose without peaks and valleys, and that is without symptoms during the low periods, (valleys). They should be taken together.


General Principles

1. All adults, even with Bartter’s, Gitelman’s and Distal Renal Tubule Acidosis, should be drinking at least eight 8-ounce glasses of fluid, mostly water, per day.

2. All Mg salts are better tolerated with at least a 100-calorie snack.

3. For it’s most rapid action, Magonate is best taken on an empty stomach, one hour before or two hours after food intake.

4. Because of Magonate’s rapid onset of effect it can be taken with another Mg salt for sudden unexpected acute symptoms, like migraine aura, migraine, muscle cramps, PMS and burning pain. Count the extra Mg as part of the daily total.

5. The total daily dose should always be taken in equally divided doses, 2-6 times a day (12-4 hours apart) and at equally divided times..

6. Always start with the smallest available amount, ½ a tablet, as far apart as possible, initially every 12 hours.

7. Always error by taking more at nigh, ½ at 10 AM and ½ at 10 PM, then ½ +1, 1+1, 1+1 ½, 2+2, 2+2 ½ etc.

8. Increase dose slowly every 1-2 days, when 2+2, go to 2+1+2 every 8 hours, etc.

9. Learn the amount of elemental Mg in each salt, so that once on 4 pills of Mag-Tab SR, or 10 of Magonate you might try substituting 1-250 mg (or 240 mg) tablet of Mg Oxide.

10. The idea is to slowly increase the dose up to the point of producing soft semi-formed bowel movements without diarrhea-The Maximum Tolerated Dose.

11. When changing Mg salts or to a different brand it is best to gradually make substitutions by alternating sources.

What if Magnesium does not meet all of your expectations/

Remember Mg does not cure everything, for example if migraine control is not perfect, accept the degree of help Mg gives and move back to retrying other drugs that may not have work before for your migraine. Although there is no proof yet, it is very possible that they will work better and at a lower dose when a patient is in PMgB than when one is in NMgB. This has been proven true for other drugs, because Mg is essential for over 300 intracellular enzymes which control how drugs function. Remember the importance of Mg in the prevention of osteoporosis.


1. The Mg in the blood vessels of the intestines rigidly control the amount of Mg absorbed. Thus any overdosing with Mg causes diarrhea, which expels that specific overdose and even the dose from before, but not a later dose if the dose has been reduced. This is the way Milk of Magnesia works, resulting in evacuation of the entire bowel. Since this salt is virtually insoluble and the Mg combines with 300 times it's weight of water, it acts as a laxative in expanding the stool mass. MgO produces 3 times and Mg Chloride produces 2 times the incident of diarrhea, than from an equal dose of Mg in MgG. (Mg Bull.1993; 15:10-12).

2. In the kidneys Mg is first excreted and then reabsorbed to the patient’s predetermined normal Mg serum level. As long as the kidneys are functioning adequately, the body cannot accumulate excess Mg in the blood. Kidney function is best determined by doing a serum creatinine level. Those with a creatinine level higher than normal need to be evaluated medically and dosing needs to be monitored with sMg levels, initially every week, since in this case the levels may get dangerously high. This is very extremely unlikely and we have not seen this in our twelve-year experience. We do not do this test on most patients with MgD, unless they are sick with other serious generalized symptoms.

3. These two responses of the body, limited absorption and limited kidney reabsorption, really protect Mg takers. In conclusion oral Mg supplementation is very safe.


The SINGLE MOST IMPORTANT means to gauge Mg therapy is to determine when you are getting enough. You must measure this day in and day out to be sure you are getting as much as necessary. If one does not demonstrate this finding in one's self, you just do not know if you are getting an adequate amount of Mg. If this important sign is present and symptoms remain unchanged for two months or so, then your doctor should order tests for serum Mg and red blood cell Mg. If either is low the symptoms will likely improve over a longer time. But if they are normal, you then know additional Mg will unlikely improve your underlying disease, even though one may need this amount of Mg to remain in PMgB.

It is my belief that many medicines, in order to be effective, require the patient to be in PMgB for the medicine to work. Thus it is important to maintain PMgB by constantly seeing this sign, by the personal observation of one's self-daily. Remember any degree of constipation is one of the most important clinical symptoms of Mg deficiency

This sign is the presence of SOFT, SEMI-FORMED BOWEL MOVEMENTS daily. The dose to result in this sign is called THE MAXIMUM TOLERATED DOSE of Mg. Mg expands the size of the stool by binding water and thus adding 300 times the weight of Mg to the bulk of the bowel movement. The point of Mg therapy is to get just sufficient to produce soft, semi-formed stools without diarrhea. If one over shoots the dose then one needs to cut back about 10 20% on every dose until there are soft, semi-formed stools. There will also occur an increased frequency of bowel movements; this is good and nothing to worry about. You have just gone from hard dry, infrequent movements, to soft, wet, semi-formed stools.


Some patients have trouble taking even their RDA for Mg, much less that needed for all symptoms of MgD. The following methods have enabled some, with erythromelalgia and/or diabetic neuropathy, to take a higher dose and still cope with Mg induced diarrhea (MgID).

1. Both Magonate and Mg Oxide can be crushed, in a pill crusher or in a Waring blender, mixed with water and sipped every hour or so, or added to food before or after cooking. Some have reached 6-10,000 mg/day, using these methods. These salts are tasteless. Do not crush Mag-tab SR, but Slo-Mag should be tried. (Slo-Mag is an enteric-coated pill containing Mg chloride that opens after the stomach).

2. We have also seen some patients that tolerate a different Brand of these two salts, because the included ingredients (fillers) are different.

3. Fiber is often considered useful to control loose bowel movements. Psyllium containing mixtures bind Mg in the bowel, thereby requiring an increased Mg dose. We have tested calcium polycarbophil, FiberCom, and it does not bind Mg. A new soluble fiber, UniFiber, from Niche (see Mag-Tab SR above) has proven to be very well tolerated and their claim that it does not bind medicines and minerals seems true. It is tasteless and suspends in many juices, only just increasing it’s thickness.

4. Those with chronic diarrhea or a sensitive stomach associated with many intestional diseases such as Crohn’s disease, Irritable Bowel Syndrome and Ulcerative Collitis, to name a few, receive significant benefit from Imodium A-D, or if more gaseous discomfort Imodium Advanced (both OTC). They have proven very helpful. Initially follow the instructions on the box, and continuing with the lowest effective dose. A dose of 0.08-0.24 mg/kg/day divided 2-3 times/day, with a maximum of 2 mg/dose has been recommended for chronic diarrhea.

5. Since about 80% of fecal mass is bacteria, effort to reestablish bacterial content should be tried by adding Probiotics, various brands of Lactobacillus Acidophilus. The theory is that since many bacteria can adapt to their environment and survive antibiotics that certainly some might live in Mg soup. The verdict is still out.

6. Apple Pectin (GNC) should be tried.

Those with MgID need to have their physician involved and have their serum electrolytes checked monthly, to assure yourself and you physician that MgID has no significant long term acid-base problems. (Personal experience using these methods showed normal serum electrolytes over four months while taking 11,000 mg of Mg /day).


1. As long as the causes are present, extra Mg will be necessary.

2. MgD is a dynamic process and subject to your daily "life style behaviors". Some of the causes, which you know may be modified (example; exercise for 20 min 3x a week helps stress). This is not possible for many causes. You will have to reassess your need for the current Mg dose, by slowly reducing the dose every few months. However, most patients need Mg for years usually at lower maintenance doses.

3. Everyone must assume that they need more Mg than the American diet provides. Moreover, being in PMgB rather than being symptomatic in NMgB is healthier. Over time the NMgB can only get worse, because each day insufficient Mg is taken by mouth additional bone reserves are depleted.

I would be willing to answer your physician’s questions about Mg, MgD and it’s treatment by Email at the above address. Medical references are available.

* Professor of Pediatrics, Associate Professor of Medicine, Former Director of the Division Allergy and Clinical Immunology, and Director of the Magnesium Research Laboratory of Jefferson Medical College, of Thomas Jefferson University, Philadelphia, PA


New Member
Tansy, thank you for this info.

I will have to go over & over it to understand, but appreciate the info.



New Member
Can't read this must on the computer, but am printing it out.

I have the book; 'Miracle of Magnesium' by Carolyn Dean M.D.

Some of this is the same material, but its always good to have more than one source of infromation.

I take from 550-600mgs a day, and am considering upping it at least another hundred mgs.

Again, thanks for all your articles, they are much appreciated.

Shalom, Shirl


New Member
Thank you so much for this very important information on Magnesium. It sounds like everyone in America is probably Mag. deficient, since we don't get enough in our normal diet. Thanks for this article---- cbella


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I just read this - I understood some of it. It's interesting that Neurontin interferes with magneisum absorption. I'm glad I stopped taking it.

I take about 800-1000 mg. of magnesium a day. I know it helps me and I encourage other people with fibromyalgia to take it. Thanks for posting this!



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Several patients I know, who had difficulty keeping their Mg levels high enough, used a magnesium sulphate cream topically at regular intervals throughout the day or a liquid ionic Mg product which was also used in a similar way. Little and often seems to feature a lot on these DDs.

TC, Tansy


I would disagree with the section that states that Mag oxide is the power house of all magnesium and gives false indication that this should be the choice to use. It's cheap and usually the one that doctors will prescribe. However it has about 2% absorbency rate. When taken, as with all magnesium products it pulls water within the body during digestion and within the intestinal walls this product turns into magnesium hydroxide. Which is nothing less than Phillips Milk of Magnesia, a laxative. And if MG deficient and needing a lot, this is not a wise choice to use. You may as well take a table spoon of the Phillips Milk of Magnesia. I'm deficient due to Giltelman Syndrome which was also noted in article. And have tried numerous magnesium supplements and have found personally that Magnesium oxide to be the worst. The article does note Mag Tab SR a slow release magnesium, and for me I have found this to be the best supplement for me. It also has about a 40% absorption ability. I think a better study is needed on this regarding the absorbency of magnesium which is more important to treat Magnesium deficiency as quality of absorption of element magnesium always surpasses quantity of the milligrams it contains.