On The Shelf
Johanna Taylor Katroscik, PharmD
Magnesium is one of the most abundant minerals in the body and is used in numerous cellular functions. It acts as a cofactor in enzymatic reactions, is an important part of energy production and glycolysis, contributes to bone development, and participates in the active transport of potassium and calcium ions across cell membranes.
Supplement manufacturers claim that magnesium helps with insomnia, muscle aches, and migraines. Meanwhile, researchers have hoped to find clinically meaningful results through trial data.
Background and function
Although magnesium comes in different salt forms, some of the most prevalent in the marketplace are magnesium citrate, magnesium hydroxide, magnesium oxide, and magnesium sulfate. Magnesium citrate is a saline laxative that works by drawing water into the colon and helping to soften stool and promoting stool movement. Its most frequent use is to help with occasional constipation or prior to a colonoscopy.
Magnesium hydroxide is another formulation that acts as a saline laxative and can be used to help treat an upset stomach or to help alleviate occasional constipation. Magnesium oxide is often taken as an antacid or to increase magnesium levels in the body. It can also be used to help with occasional constipation but is thought to have lower bioavailability than other magnesium formulations. Magnesium sulfate is also known as Epsom salt and can be used both orally and topically. As an oral supplement, it acts as a laxative to help with constipation. As a topical agent, it can be used to help relax muscles or relieve pain from bruises or sprains.
Is there a benefit?
Studies have not addressed all beneficial claims of magnesium, but research has been conducted on the impact of magnesium intake on blood pressure, type 2 diabetes, osteoporosis, and migraine headaches.
Several metaanalyses have examined the effect of magnesium supplements on hypertension. Results from these have shown that magnesium may be connected to slightly decreased blood pressure (average reduction was approximately 2–4 mmHg). Other studies also associated daily magnesium supplementation with a decreased risk of ischemic heart disease and stroke.
Several prospective cohort studies and metaanalyses have looked at the effect of a daily magnesium supplement on type 2 diabetes prevention. These data show an association of magnesium supplementation with a decreased risk of developing type 2 diabetes. Unfortunately, data are lacking on whether it can help with glycemic control for patients who have already been diagnosed with type 2 diabetes.
Limited studies suggest that magnesium supplementation or an increase in dietary magnesium may help in preventing bone loss and increasing bone density in women who are postmenopausal.
Lastly, several studies show that magnesium supplements may be beneficial to patients who experience migraine headaches. The American Academy of Neurology and the American Headache Society state that magnesium therapy is ‘probably effective’ when used to prevent migraines. They recommend that if using magnesium for migraine prevention, it should be done in partnership with a health care provider.
Daily requirements and dietary sources
Recommended dietary allowance of magnesium for adults is around 300 mg to 400 mg per day. Data suggest that most people eat less than the recommended daily amount of magnesium. However, the kidneys help prevent magnesium deficiency by limiting urinary excretion of it.
Magnesium is available in different foods and can be found in higher amounts in pumpkin seeds, spinach, cashews, peanuts, and black beans.
What to tell your patients
Most patients can get adequate amounts of magnesium through a healthy and well-balanced diet. That being said, several medications have been shown to deplete magnesium levels and patients who take these medications may have lower levels of magnesium than the general population. These medication classes include proton pump inhibitors, and loop and thiazide diuretics.
Magnesium can interact with several medications by binding to them and making them either inactive or less active. These medications include bisphosphonates, tetracycline antibiotics, and quinolone antibiotics. Patients should be counseled to separate ingestion of magnesium and these medications by at least 2 hours. Most magnesium supplements are safe to take on a short-term basis, but very high levels of magnesium can be toxic and potentially fatal. ■