- What is Magnesium
- Sources of Magnesium
- Magnesium and health
- Can Excess Magnesium be harmful ?
What is Magnesium
Magnesium, an abundant mineral in the body that the body needs to stay healthy, is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives) 1). Magnesium is important for many processes in the body, including regulating muscle and nerve function, blood sugar levels, and blood pressure and making protein, bone, and DNA. Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation 2), 3), 4).
Magnesium is required for energy production, oxidative phosphorylation, and glycolysis. It contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm 5).
An adult body contains approximately 25 g magnesium, with 50% to 60% present in the bones and most of the rest in soft tissues 6). Less than 1% of total magnesium is in blood serum, and these levels are kept under tight control. Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles (mmol)/L 7), 8). Hypomagnesemia is defined as a serum magnesium level less than 0.75 mmol/L 9). Magnesium homeostasis is largely controlled by the kidney, which typically excretes about 120 mg magnesium into the urine each day 10). Urinary excretion is reduced when magnesium status is low 11).
Assessing magnesium status is difficult because most magnesium is inside cells or in bone 12). The most commonly used and readily available method for assessing magnesium status is measurement of serum magnesium concentration, even though serum levels have little correlation with total body magnesium levels or concentrations in specific tissues 13). Other methods for assessing magnesium status include measuring magnesium concentrations in erythrocytes, saliva, and urine; measuring ionized magnesium concentrations in blood, plasma, or serum; and conducting a magnesium-loading (or “tolerance”) test. No single method is considered satisfactory 14). Some experts 15) but not others 16) consider the tolerance test (in which urinary magnesium is measured after parenteral infusion of a dose of magnesium) to be the best method to assess magnesium status in adults. To comprehensively evaluate magnesium status, both laboratory tests and a clinical assessment might be required 17).
How much magnesium do you need ?
Intake recommendations for magnesium and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) 18). DRI is the general term for a set of reference values used to plan and assess nutrient intakes of healthy people. These values, which vary by age and sex, include:
- Recommended Dietary Allowance (RDA): average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals.
- Adequate Intake (AI): established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy.
- Estimated Average Requirement (EAR): average daily level of intake estimated to meet the requirements of 50% of healthy individuals. It is usually used to assess the adequacy of nutrient intakes in population groups but not individuals.
- Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects.
Table 1 lists the current Recommended Dietary Allowances (RDAs) for magnesium 19). For infants from birth to 12 months, the Food and Nutrition Board established an Adequate Intake (AI) for magnesium that is equivalent to the mean intake of magnesium in healthy, breastfed infants, with added solid foods for ages 7–12 months.
The amount of magnesium you need depends on your age and sex. Average daily recommended amounts are listed below in milligrams (mg).
Table 1: Recommended Dietary Allowances (RDAs) for Magnesium
|Birth to 6 months||30 mg*||30 mg*|
|7–12 months||75 mg*||75 mg*|
|1–3 years||80 mg||80 mg|
|4–8 years||130 mg||130 mg|
|9–13 years||240 mg||240 mg|
|14–18 years||410 mg||360 mg||400 mg||360 mg|
|19–30 years||400 mg||310 mg||350 mg||310 mg|
|31–50 years||420 mg||320 mg||360 mg||320 mg|
|51+ years||420 mg||320 mg|
*Adequate Intake (AI)[Source 20)]
Sources of Magnesium
Magnesium Rich Foods
Magnesium is widely distributed in plant and animal foods and in beverages. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources 21), 22). In general, foods containing dietary fiber provide magnesium. Magnesium is also added to some breakfast cereals and other fortified foods. Some types of food processing, such as refining grains in ways that remove the nutrient-rich germ and bran, lower magnesium content substantially 23). Selected food sources of magnesium are listed in Table 2.
Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body 24), 25).
Table 2: Magnesium Rich Foods
|Almonds, dry roasted, 1 ounce||80||20|
|Spinach, boiled, ½ cup||78||20|
|Cashews, dry roasted, 1 ounce||74||19|
|Peanuts, oil roasted, ¼ cup||63||16|
|Cereal, shredded wheat, 2 large biscuits||61||15|
|Soymilk, plain or vanilla, 1 cup||61||15|
|Black beans, cooked, ½ cup||60||15|
|Edamame, shelled, cooked, ½ cup||50||13|
|Peanut butter, smooth, 2 tablespoons||49||12|
|Bread, whole wheat, 2 slices||46||12|
|Avocado, cubed, 1 cup||44||11|
|Potato, baked with skin, 3.5 ounces||43||11|
|Rice, brown, cooked, ½ cup||42||11|
|Yogurt, plain, low fat, 8 ounces||42||11|
|Breakfast cereals, fortified with 10% of the DV for magnesium||40||10|
|Oatmeal, instant, 1 packet||36||9|
|Kidney beans, canned, ½ cup||35||9|
|Banana, 1 medium||32||8|
|Salmon, Atlantic, farmed, cooked, 3 ounces||26||7|
|Milk, 1 cup||24–27||6–7|
|Halibut, cooked, 3 ounces||24||6|
|Raisins, ½ cup||23||6|
|Chicken breast, roasted, 3 ounces||22||6|
|Beef, ground, 90% lean, pan broiled, 3 ounces||20||5|
|Broccoli, chopped and cooked, ½ cup||12||3|
|Rice, white, cooked, ½ cup||10||3|
|Apple, 1 medium||9||2|
|Carrot, raw, 1 medium||7||2|
*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for magnesium is 400 mg for adults and children aged 4 and older. However, the FDA does not require food labels to list magnesium content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.[Source 26)]
The U.S. Department of Agriculture’s (USDA’s) Nutrient Database 27) lists the nutrient content of many foods and provides comprehensive list of foods containing magnesium arranged by nutrient content 28) and by food name 29).
Tap, mineral, and bottled waters can also be sources of magnesium, but the amount of magnesium in water varies by source and brand (ranging from 1 mg/L to more than 120 mg/L) 30).
What foods provide magnesium ?
Magnesium is found naturally in many foods and is added to some fortified foods. You can get recommended amounts of magnesium by eating a variety of foods, including the following:
- Legumes, nuts, seeds, whole grains, and green leafy vegetables (such as spinach)
- Fortified breakfast cereals and other fortified foods
- Milk, yogurt, and some other milk products
What are other sources of magnesium?
Magnesium supplements are available in a variety of forms, including magnesium oxide, citrate, and chloride 31), 32). The Supplement Facts panel on a dietary supplement label declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound.
Absorption of magnesium from different kinds of magnesium supplements varies. Forms of magnesium that dissolve well in liquid are more completely absorbed in the gut than less soluble forms 33), 34). Small studies have found that magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bioavailable than magnesium oxide and magnesium sulfate 35), 36), 37), 38), 39). One study found that very high doses of zinc from supplements (142 mg/day) can interfere with magnesium absorption and disrupt the magnesium balance in the body 40).
Magnesium is a primary ingredient in some laxatives 41). Phillips’ Milk of Magnesia®, for example, provides 500 mg elemental magnesium (as magnesium hydroxide) per tablespoon; the directions advise taking up to 4 tablespoons/day for adolescents and adults. Although such a dose of magnesium is well above the safe upper level, some of the magnesium is not absorbed because of the medication’s laxative effect. Magnesium is also included in some remedies for heartburn and upset stomach due to acid indigestion 42). Extra-strength Rolaids®, for example, provides 55 mg elemental magnesium (as magnesium hydroxide) per tablet, although Tums® is magnesium free.
Are you getting enough magnesium ?
Dietary surveys of people in the United States consistently show that intakes of magnesium are lower than recommended amounts. An analysis of data from the National Health and Nutrition Examination Survey (NHANES) of 2005–2006 found that a majority of Americans of all ages ingest less magnesium from food than their respective Estimated Average Requirements (EARs); adult men aged 71 years and older and adolescent females are most likely to have low intakes 43). In a study using data from NHANES 2003–2006 to assess mineral intakes among adults, average intakes of magnesium from food alone were higher among users of dietary supplements (350 mg for men and 267 mg for women, equal to or slightly exceeding their respective EARs) than among nonusers (268 mg for men and 234 for women) 44). When supplements were included, average total intakes of magnesium were 449 mg for men and 387 mg for women, well above EAR levels.
No current data on magnesium status in the United States are available. Determining dietary intake of magnesium is the usual proxy for assessing magnesium status. NHANES has not determined serum magnesium levels in its participants since 1974 45), and magnesium is not evaluated in routine electrolyte testing in hospitals and clinics 46).
What happens if you don’t get enough magnesium ?
In the short term, getting too little magnesium does not produce obvious symptoms. When healthy people have low intakes, the kidneys help retain magnesium by limiting the amount lost in urine. However, habitually low magnesium intakes for a long period of time or excessive losses of magnesium due to certain health conditions and chronic alcoholism can lead to magnesium deficiency. In addition, some medical conditions and medications interfere with the body’s ability to absorb magnesium or increase the amount of magnesium that the body excretes, which can also lead to magnesium deficiency.
Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures, personality changes, abnormal heart rhythms, and coronary spasms can occur. Severe magnesium deficiency can result in hypocalcemia or hypokalemia (low serum calcium or potassium levels, respectively) because mineral homeostasis is disrupted 47).
Groups at Risk of Magnesium Inadequacy
The following groups of people are more likely than others to get too little magnesium:
- People with gastrointestinal diseases (such as Crohn’s disease and celiac disease)
- People with type 2 diabetes
- People with long-term alcoholism
- Older people
Magnesium inadequacy can occur when intakes fall below the RDA but are above the amount required to prevent overt deficiency. The following groups are more likely than others to be at risk of magnesium inadequacy because they typically consume insufficient amounts or they have medical conditions (or take medications) that reduce magnesium absorption from the gut or increase losses from the body.
People with gastrointestinal diseases
The chronic diarrhea and fat malabsorption resulting from Crohn’s disease, gluten-sensitive enteropathy (celiac disease), and regional enteritis can lead to magnesium depletion over time 48). Resection or bypass of the small intestine, especially the ileum, typically leads to malabsorption and magnesium loss 49).
People with type 2 diabetes
Magnesium deficits and increased urinary magnesium excretion can occur in people with insulin resistance and/or type 2 diabetes 50). The magnesium loss appears to be secondary to higher concentrations of glucose in the kidney that increase urine output 51).
People with alcohol dependence
Magnesium deficiency is common in people with chronic alcoholism 52). In these individuals, poor dietary intake and nutritional status; gastrointestinal problems, including vomiting, diarrhea, and steatorrhea (fatty stools) resulting from pancreatitis; renal dysfunction with excess excretion of magnesium into the urine; phosphate depletion; vitamin D deficiency; acute alcoholic ketoacidosis; and hyperaldosteronism secondary to liver disease can all contribute to decreased magnesium status 53).
Older adults have lower dietary intakes of magnesium than younger adults 54). In addition, magnesium absorption from the gut decreases and renal magnesium excretion increases with age 55). Older adults are also more likely to have chronic diseases or take medications that alter magnesium status, which can increase their risk of magnesium depletion 56).
Therapeutic use of Magnesium
Magnesium is a primary ingredient in some laxatives 57). Phillips’ Milk of Magnesia®, for example, provides 500 mg elemental magnesium (as magnesium hydroxide) per tablespoon; the directions advise taking up to 4 tablespoons/day for adolescents and adults 58). (Although such a dose of magnesium is well above the safe upper level, some of the magnesium is not absorbed because of the medication’s laxative effect.) Magnesium is also included in some remedies for heartburn and upset stomach due to acid indigestion 59). Extra-strength Rolaids®, for example, provides 55 mg elemental magnesium (as magnesium hydroxide) per tablet 60), although Tums® is magnesium free 61).
Magnesium and health
Scientists are studying magnesium to understand how it affects health. Here are some examples of what this research has shown.
High blood pressure and heart disease
High blood pressure is a major risk factor for heart disease and stroke. Magnesium supplements might decrease blood pressure, but only by a small amount. Some studies show that people who have more magnesium in their diets have a lower risk of some types of heart disease and stroke.
A meta-analysis of 12 clinical trials found that magnesium supplementation for 8–26 weeks in 545 hypertensive participants resulted in only a small reduction (2.2 mmHg) in diastolic blood pressure 62). The dose of magnesium ranged from approximately 243 to 973 mg/day. The authors of another meta-analysis of 22 studies with 1,173 normotensive and hypertensive adults concluded that magnesium supplementation for 3–24 weeks decreased systolic blood pressure by 3–4 mmHg and diastolic blood pressure by 2–3 mmHg 63). The effects were somewhat larger when supplemental magnesium intakes of the participants in the nine crossover-design trials exceeded 370 mg/day. A diet containing more magnesium because of added fruits and vegetables, more low-fat or non-fat dairy products, and less fat overall was shown to lower systolic and diastolic blood pressure by an average of 5.5 and 3.0 mmHg, respectively 64). However, this Dietary Approaches to Stop Hypertension (DASH) diet also increases intakes of other nutrients, such as potassium and calcium, that are associated with reductions in blood pressure, so any independent contribution of magnesium cannot be determined.
Several prospective studies have examined associations between magnesium intakes and heart disease. The Atherosclerosis Risk in Communities study assessed heart disease risk factors and levels of serum magnesium in a cohort of 14,232 white and African-American men and women aged 45 to 64 years at baseline 65). Over an average of 12 years of follow-up, individuals in the highest quartile of the normal physiologic range of serum magnesium (at least 0.88 mmol/L) had a 38% reduced risk of sudden cardiac death compared with individuals in the lowest quartile (0.75 mmol/L or less). However, dietary magnesium intakes had no association with risk of sudden cardiac death. Another prospective study tracked 88,375 female nurses in the United States to determine whether serum magnesium levels measured early in the study and magnesium intakes from food and supplements assessed every 2 to 4 years were associated with sudden cardiac death over 26 years of follow-up 66). Women in the highest compared with the lowest quartile of ingested and plasma magnesium concentrations had a 34% and 77% lower risk of sudden cardiac death, respectively. Another prospective population study of 7,664 adults aged 20 to 75 years in the Netherlands who did not have cardiovascular disease found that low urinary magnesium excretion levels (a marker for low dietary magnesium intake) were associated with a higher risk of ischemic heart disease over a median follow-up period of 10.5 years. Plasma magnesium concentrations were not associated with risk of ischemic heart disease 67). A systematic review and meta-analysis of prospective studies found that higher serum levels of magnesium were significantly associated with a lower risk of cardiovascular disease, and higher dietary magnesium intakes (up to approximately 250 mg/day) were associated with a significantly lower risk of ischemic heart disease caused by a reduced blood supply to the heart muscle 68).
Higher magnesium intakes might reduce the risk of stroke. In a meta-analysis of 7 prospective trials with a total of 241,378 participants, an additional 100 mg/day magnesium in the diet was associated with an 8% decreased risk of total stroke, especially ischemic rather than hemorrhagic stroke 69). One limitation of such observational studies, however, is the possibility of confounding with other nutrients or dietary components that could also affect the risk of stroke. But in many of these studies, it’s hard to know how much of the effect was due to magnesium as opposed to other nutrients.
A large, well-designed clinical trial is needed to better understand the contributions of magnesium from food and dietary supplements to heart health and the primary prevention of cardiovascular disease.
Type 2 diabetes
People with higher amounts of magnesium in their diets tend to have a lower risk of developing type 2 diabetes. Magnesium helps the body break down sugars and might help reduce the risk of insulin resistance (a condition that leads to diabetes) 70), 71). Scientists are studying whether magnesium supplements might help people who already have type 2 diabetes control their disease. More research is needed to better understand whether magnesium can help treat diabetes. The American Diabetes Association states that there is insufficient evidence to support the routine use of magnesium to improve glycemic control in people with diabetes 72). It further notes that there is no clear scientific evidence that vitamin and mineral supplementation benefits people with diabetes who do not have underlying nutritional deficiencies.
Hypomagnesemia might worsen insulin resistance, a condition that often precedes diabetes, or it might be a consequence of insulin resistance 73). Diabetes leads to increased urinary losses of magnesium, and the subsequent magnesium inadequacy might impair insulin secretion and action, thereby worsening diabetes control 74).
Most investigations of magnesium intake and risk of type 2 diabetes have been prospective cohort studies. A meta-analysis of 7 of these studies, which included 286,668 patients and 10,912 cases of diabetes over 6 to 17 years of follow-up, found that a 100 mg/day increase in total magnesium intake decreased the risk of diabetes by a statistically significant 15% 75). Another meta-analysis of 8 prospective cohort studies that followed 271,869 men and women over 4 to 18 years found a significant inverse association between magnesium intake from food and risk of type 2 diabetes; the relative risk reduction was 23% when the highest to lowest intakes were compared 76).
A 2011 meta-analysis of prospective cohort studies of the association between magnesium intake and risk of type 2 diabetes included 13 studies with a total of 536,318 participants and 24,516 cases of diabetes 77). The mean length of follow-up ranged from 4 to 20 years. Investigators found an inverse association between magnesium intake and risk of type 2 diabetes in a dose-responsive fashion, but this association achieved statistical significance only in overweight (body mass index [BMI] 25 or higher) but not normal-weight individuals (BMI less than 25). Again, a limitation of these observational studies is the possibility of confounding with other dietary components or lifestyle or environmental variables that are correlated with magnesium intake.
Only a few small, short-term clinical trials have examined the potential effects of supplemental magnesium on control of type 2 diabetes and the results are conflicting 78), 79). For example, 128 patients with poorly controlled diabetes in a Brazilian clinical trial received a placebo or a supplement containing either 500 mg/day or 1,000 mg/day magnesium oxide (providing 300 or 600 mg elemental magnesium, respectively) 80). After 30 days of supplementation, plasma, cellular, and urine magnesium levels increased in participants receiving the larger dose of the supplement, and their glycemic control improved. In another small trial in Mexico, participants with type 2 diabetes and hypomagnesemia who received a liquid supplement of magnesium chloride (providing 300 mg/day elemental magnesium) for 16 weeks showed significant reductions in fasting glucose and glycosylated hemoglobin concentrations compared with participants receiving a placebo, and their serum magnesium levels became normal 81). In contrast, neither a supplement of magnesium aspartate (providing 369 mg/day elemental magnesium) nor a placebo taken for 3 months had any effect on glycemic control in 50 patients with type 2 diabetes who were taking insulin 82).
The American Diabetes Association states that there is insufficient evidence to support the routine use of magnesium to improve glycemic control in people with diabetes 83). It further notes that there is no clear scientific evidence that vitamin and mineral supplementation benefits people with diabetes who do not have underlying nutritional deficiencies.
Magnesium is important for healthy bones. Magnesium is involved in bone formation and influences the activities of osteoblasts and osteoclasts 84). Magnesium also affects the concentrations of both parathyroid hormone and the active form of vitamin D, which are major regulators of bone homeostasis. Several population-based studies have found positive associations between magnesium intake and bone mineral density in both men and women 85). Other research has found that women with osteoporosis have lower serum magnesium levels than women with osteopenia and those who do not have osteoporosis or osteopenia 86). These and other findings indicate that magnesium deficiency might be a risk factor for osteoporosis 87).
Although limited in number, studies suggest that increasing magnesium intakes from food or supplements might increase bone mineral density in postmenopausal and elderly women 88). For example, one short-term study found that 290 mg/day elemental magnesium (as magnesium citrate) for 30 days in 20 postmenopausal women with osteoporosis suppressed bone turnover compared with placebo, suggesting that bone loss decreased 89).
Diets that provide recommended levels of magnesium enhance bone health, but further research is needed to elucidate the role of magnesium in the prevention and management of osteoporosis.
People who have migraine headaches sometimes have low levels of magnesium in their blood and other tissues 90). Several small studies found that magnesium supplements can modestly reduce the frequency of migraines.
However, research on the use of magnesium supplements to prevent or reduce symptoms of migraine headaches is limited. Three of four small, short-term, placebo-controlled trials found modest reductions in the frequency of migraines in patients given up to 600 mg/day magnesium 91). The authors of a review on migraine prophylaxis suggested that taking 300 mg magnesium twice a day, either alone or in combination with medication, can prevent migraines 92).
In their evidence-based guideline update, the American Academy of Neurology and the American Headache Society concluded that magnesium therapy is “probably effective” for migraine prevention 93). Because the typical dose of magnesium used for migraine prevention exceeds the UL, this treatment should be used only under the direction and supervision of a healthcare provider.
More research is needed to determine whether magnesium supplements can help reduce the risk of migraines or ease migraine symptoms.
Can Excess Magnesium be harmful ?
Magnesium that is naturally present in food is not harmful and does not need to be limited. Too much magnesium from food does not pose a health risk in healthy individuals because the kidneys eliminate excess amounts in the urine 94). But magnesium in dietary supplements and medications should not be consumed in amounts above the upper limit, unless recommended by a health care provider.
High intakes of magnesium from dietary supplements and medications can cause diarrhea, nausea, and abdominal cramping. Extremely high intakes of magnesium can lead to irregular heartbeat and cardiac arrest.
Forms of magnesium most commonly reported to cause diarrhea include magnesium carbonate, chloride, gluconate, and oxide 95). The diarrhea and laxative effects of magnesium salts are due to the osmotic activity of unabsorbed salts in the intestine and colon and the stimulation of gastric motility 96).
The Food and Nutrition Board has established ULs for magnesium that apply only to supplemental magnesium for healthy infants, children, and adults (see Table 3)
Table 3: Tolerable Upper Intake Levels (ULs) for Supplemental Magnesium
|Birth to 12 months||None established||None established|
|1–3 years||65 mg||65 mg|
|4–8 years||110 mg||110 mg|
|9–18 years||350 mg||350 mg||350 mg||350 mg|
|19+ years||350 mg||350 mg||350 mg||350 mg|
Very large doses of magnesium-containing laxatives and antacids (typically providing more than 5,000 mg/day magnesium) have been associated with magnesium toxicity 98), including fatal hypermagnesemia in a 28-month-old boy 99) and an elderly man 100). Symptoms of magnesium toxicity, which usually develop after serum concentrations exceed 1.74–2.61 mmol/L, can include hypotension, nausea, vomiting, facial flushing, retention of urine, ileus, depression, and lethargy before progressing to muscle weakness, difficulty breathing, extreme hypotension, irregular heartbeat, and cardiac arrest 101). The risk of magnesium toxicity increases with impaired renal function or kidney failure because the ability to remove excess magnesium is reduced or lost 102), 103).
Tell your doctor, pharmacist, and other health care providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.
Interactions with Medications
Several types of medications have the potential to interact with magnesium supplements or affect magnesium status. A few examples are provided below. People taking these and other medications on a regular basis should discuss their magnesium intakes with their healthcare providers.
Magnesium-rich supplements or medications can decrease the absorption of oral bisphosphonates, such as alendronate (Fosamax®), used to treat osteoporosis 104). Use of magnesium-rich supplements or medications and oral bisphosphonates should be separated by at least 2 hours.
Magnesium can form insoluble complexes with tetracyclines, such as demeclocycline (Declomycin®) and doxycycline (Vibramycin®), as well as quinolone antibiotics, such as ciprofloxacin (Cipro®) and levofloxacin (Levaquin®). These antibiotics should be taken at least 2 hours before or 4–6 hours after a magnesium-containing supplement 105).
Chronic treatment with loop diuretics, such as furosemide (Lasix®) and bumetanide (Bumex®), and thiazide diuretics, such as hydrochlorothiazide (Aquazide H®) and ethacrynic acid (Edecrin®), can increase the loss of magnesium in urine and lead to magnesium depletion 106). In contrast, potassium-sparing diuretics, such as amiloride (Midamor®) and spironolactone (Aldactone®), reduce magnesium excretion 107).
Proton pump inhibitors
Prescription proton pump inhibitor (PPI) drugs, such as esomeprazole magnesium (Nexium®) and lansoprazole (Prevacid®), when taken for prolonged periods (typically more than a year) can cause hypomagnesemia 108). In cases that FDA reviewed, magnesium supplements often raised the low serum magnesium levels caused by PPIs. However, in 25% of the cases, supplements did not raise magnesium levels and the patients had to discontinue the PPI. FDA advises healthcare professionals to consider measuring patients’ serum magnesium levels prior to initiating long-term PPI treatment and to check magnesium levels in these patients periodically 109).
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