If you are experiencing magnesium deficiency symptoms and need to take supplements, the correct dosage can depend on several factors. You should consider the type of magnesium in the supplement and any health conditions that may affect bioavailability. Too high a dose of magnesium can be dangerous.
Health Benefits of Magnesium
Magnesium, the fourth most abundant mineral in your body, is a cofactor for the metabolism of over 300 enzymatic reactions, including energy production and protein synthesis. It is also required for DNA and RNA synthesis and reproduction, according to a review published in Nutrients in September 2015. Furthermore, this mineral regulates blood pressure, insulin metabolism, heart health, nerve transmission and neuromuscular conduction.
With all these health benefits, magnesium plays an important role in the prevention and treatment of many chronic diseases. Low levels of this mineral have been linked with hypertension, Alzheimer's disease, type II diabetes, cardiovascular disease and stroke. Migraine headaches and attention deficit hyperactivity disorder are all potential side effects, according to the above review.
Moreover, magnesium contributes to the structural development of bone. With about 60 percent of total body magnesium being found in the bones, it's important to maintain adequate levels to help maintain bone density as you age. A large study featured in Nutrients in October 2017 suggests that dietary magnesium plays a role in musculoskeletal health and may prevent sarcopenia, osteoporosis and frailty, falls and fractures.
Getting Adequate Magnesium
The optimal daily intake of magnesium necessary to maintain good health has been established by the board of health and listed by the National Institutes of Health (NIH). These recommendations, which include magnesium from all sources, depend on your age and sex and are as follows:
- Children 9 to 13 years: 240 milligrams
- Teens 14 to 18 years: 410 milligrams for boys; 360 milligrams for girls
- Adult men: 400 to 420 milligrams
- Adult women: 310 to 320 milligrams
- Pregnant women: 350 to 360 milligrams
- Lactating women: 310 to 360 milligrams
This nutrient is not as readily available as other minerals in food. Additionally, cooking and processing deplete magnesium, says the University of Kansas Medical Center.
Foods that are high in fiber usually contain the most magnesium. About 30 to 40 percent of dietary magnesium from food is typically absorbed in the gut, according to the NIH. Some of the best dietary sources include:
- Legumes, nuts and seeds
- Whole grains
- Green leafy vegetables, such as spinach
- Fortified foods, such as breakfast cereals
- Dairy products, including milk and yogurt
Water, including well water and bottled water, provides magnesium too.
Magnesium Deficiency Causes
Since your kidneys limit the urinary excretion of magnesium, a deficiency is not common and may go unnoticed for a long time. Low magnesium levels might be due to a poor or restrictive diet or result from a variety of conditions that can cause your body to lose this mineral quicker than it can be replenished.
According to MedlinePlus, magnesium deficiency causes may include:
- Excessive alcohol use
- Hyperaldosteronism (adrenal gland releases too much of the hormone aldosterone)
- High blood calcium level, called hypercalcemia
- Kidney disease
- Long-term diarrhea
- Taking certain medicines, such as proton pump inhibitors, diuretics, some antibiotics
- Inflammation of the pancreas
- Uncontrolled diabetes
- Preeclampsia (high blood pressure and protein in the urine in a pregnant woman)
- Inflammation of the lining of the large intestine and rectum, called ulcerative colitis
If you have a condition that puts you at risk for nutrient deficiencies, ask your doctor to prescribe a magnesium deficiency test, which requires a blood sample. The normal range for blood magnesium levels is 1.7 to 2.2 milligrams per deciliter, reports MedlinePlus.
With low blood levels, you may experience certain symptoms that might indicate you need to take a supplement. Watch out for these 11 warning signs of magnesium deficiency, recommends the NIH:
Severely low levels of magnesium in the blood, called hypomagnesemia, can result in low calcium levels because of disruption of the mineral balance in your body. Shortages of magnesium and calcium may cause neurological problems that, left untreated, can lead to developmental delay, intellectual disability, a failure to grow and possibly, heart failure.
Correcting a Magnesium Deficiency
Many Americans are deficient in this nutrient, states the NIH. If magnesium levels in your body are too low, increasing your dietary intake of magnesium from food may not be enough. Supplements may help replenish your magnesium stores, but it can take up to six months of treatment to recover from severe deficiencies, according to the University of Kansas Medical Center.
Magnesium supplements are available over the counter or by prescription in tablet, capsule, extended-release, powder, chewable and liquid form. Many multivitamin and mineral supplements, as well as laxatives and antacids, contain magnesium. You can choose from many stand-alone forms of dietary supplements. Since each kind is made by combining different salts, they can vary in their magnesium content and absorbability.
Some of the forms of oral magnesium supplements, according to the University of Kansas, include:
- Magnesium citrate
- Magnesium lactate
- Magnesium aspartate
- Magnesium chloride
- Magnesium oxide
- Magnesium sulfate
- Magnesium malate
- Magnesium taurate
Forms of magnesium that dissolve in liquid are better absorbed into the gut. The NIH suggests that citrate, lactate, aspartate and chloride forms of magnesium are more bioavailable than magnesium oxide and magnesium sulfate.
There's no disputing the effectiveness of oral magnesium supplements, but an alternate method of administration was discussed in a study published in Nutrients in July 2017. Magnesium may have the potential to be taken in through the skin, in a process called transdermal absorption. This application can be through magnesium-containing sprays, magnesium flakes and magnesium salt baths, such as the well-known Epsom salts.
Some sources say that transdermal magnesium application may be the best way to replenish the mineral since every cell in the body bathes in it. Magnesium passes directly into your tissues through the skin, where it may quickly be transported to cells throughout the body. Furthermore, the transdermal absorption of magnesium is presented as being more effective due to nearly 100 percent absorption with fewer side effects.
The study in Nutrients evaluated the potential for transdermal application to get into the lymphatic system beneath the dermis and enter the circulatory system, bypassing the GI tract and thereby increasing serum magnesium. However, scientists concluded that more research is needed before they could recommend the application of transdermal magnesium.
How to Determine the Dosage
The dosage of magnesium you may need from a supplement depends on your medical problem and the strength of the pill. The daily tolerable upper level of 350 milligrams has been determined as the maximum safe dose of magnesium from supplements, according to the NIH. Higher doses of supplements and medications are often used to treat certain conditions, but these should only be taken under the supervision of a healthcare provider.
To treat low magnesium levels, the dose is determined for each individual based on the severity of deficiency. Always consult your physician to determine the dosage that is appropriate for your needs. Some examples of oral doses that are used, depending on the type of magnesium supplement, include:
- Magnesium sulfate — a dosage of 3 grams taken every six hours, four times a day
- Magnesium chloride — 5 percent solution by mouth daily for 16 weeks
- Magnesium lactate — 10.4 millimoles taken by mouth daily for three months
- Magnesium citrate — 400 to 600 milligrams at bedtime or 200 to 300 milligrams two to three times a day
- Magnesium-rich mineral water (Hepar) — 110 milligrams per liter
Side Effects and Toxicity
You should not take magnesium supplements if you have kidney failure, bowel obstruction, autoimmune neuromuscular disease or heart block, warns the University of Kansas.
High doses of magnesium from some kinds of supplements may cause mild side effects, including diarrhea, nausea and stomach cramps. According to the NIH, the forms of magnesium most likely to cause these symptoms are:
- Magnesium carbonate
- Magnesium chloride
- Magnesium gluconate
- Magnesium oxide
Dosages in the range of 5,000 milligrams can lead to excessive magnesium in the blood, a condition called hypermagnesemia, warns the NIH. Although this condition is relatively uncommon, the elderly and people with renal insufficiency and bowel disorders may be more susceptible, with results possibly leading to dangerous neuromuscular, cardiac or nervous disorders, reports the July 2017 study in Nutrients.
According to the Mayo Clinic, symptoms of overdose may include:
- Blurred or double vision
- Dizziness or fainting
- Severe drowsiness
- Increased or decreased urination
- Slow heartbeat
- Trouble breathing
While it's important that you maintain your magnesium levels in a healthy range, be cautious with your supplement use. Follow the advice of your doctor or the directions on the label to prevent an overdose.
Magnesium Interactions With Medications
Magnesium supplements have the potential to interact with other medications. The NIH advises that if you are taking any of the following drugs, let your doctor know before using magnesium supplements.
- Bisphosphonates — Magnesium supplements can decrease the absorption of
medications that treat osteoporosis, such as Fosamax, so these types of
drugs should be taken at least two hours apart.
- Antibiotics — Magnesium can form insoluble complexes with
tetracyclines and certain types of antibiotics, such as Cipro and Levaquin. Take
these antibiotics at least two hours before or four to six hours after a magnesium-containing
- Diuretics –— Prolonged treatment with diuretics can increase the
loss of magnesium in urine and lead to magnesium depletion. Instead, use
potassium-sparing diuretics, such as Midamor or Aldactone, to reduce magnesium
- Proton pump inhibitors — Prescription proton pump inhibitor drugs, such as Nexium and Prevacid, taken for prolonged periods can cause hypomagnesemia. The FDA advises doctors to consider measuring patients' serum magnesium levels prior to prescribing long-term proton pump inhibitor treatment and to monitor magnesium levels periodically, according to the NIH.
- Nutrients: "Magnesium in Prevention and Therapy"
- Nutrients: "Dietary Magnesium May Be Protective for Aging of Bone and Skeletal Muscle in Middle and Younger Older Age Men and Women: Cross-Sectional Findings from the UK Biobank Cohort"
- National Institutes of Health: "Magnesium"
- University of Kansas Medical Center: "The Benefits of Magnesium"
- MedlinePlus: "Magnesium Blood Test: What Abnormal Results Mean"
- HealthDirect: "Magnesium"
- MedlinePlus: "Low Magnesium Level"
- U.S. National Library of Medicine: Genetics Home Reference: "Hypomagnesemia with Secondary Hypocalcemia"
- Nutrients: "Myth or Reality—Transdermal Magnesium?"
- RxList: "Magnesium"
- MayoClinic: "Magnesium Supplement (Oral Route, Parenteral Route)"