magnesium citrate

Magnesium citrate is a dietary-supplement form of magnesium, an essential mineral the body needs for more than 300 enzyme-driven biochemical reactions, including muscle and nerve function, normal heart rhythm, blood-sugar and blood-pressure regulation, bone structure, and energy and protein production. In this form the mineral is bound to citric acid; the NIH notes that magnesium forms that dissolve well in liquid — such as citrate, lactate, and chloride — tend to be absorbed more completely than less-soluble forms such as magnesium oxide. At higher doses, magnesium salts also act as an osmotic laxative, which is why magnesium-containing products are sometimes used to relieve occasional constipation.

The NIH treats most therapeutic claims cautiously, and for most healthy people food is the preferred source. For blood pressure, the NIH says magnesium supplements "might decrease blood pressure, but only by a small amount," and that it is often hard to separate magnesium's effect from that of other nutrients. For type 2 diabetes, people with higher dietary magnesium tend to have a lower risk of developing the disease, but the NIH states that "more research is needed to better understand whether magnesium can help treat diabetes." For bone health, higher magnesium intake is associated with higher bone mineral density and "might help" older women, while the NIH again says more research is needed before concluding it reduces osteoporosis risk. For migraine, people with migraines sometimes have low magnesium, and several small studies suggest supplements may modestly reduce attack frequency, but the NIH advises using magnesium for this only under a clinician's care and says more research is needed. MedlinePlus states plainly that "taking magnesium supplements is not currently advised" for most healthy people, who can usually meet their needs through food.

The Recommended Dietary Allowance for elemental magnesium is roughly 400-420 mg/day for adult men and 310-320 mg/day for adult women, counted across food, beverages, and supplements. For supplemental magnesium specifically, the NIH sets a Tolerable Upper Intake Level of 350 mg/day for adults — a limit driven by the fact that higher supplemental doses commonly cause diarrhea; it applies only to magnesium from supplements and medications, not to magnesium naturally present in food. Laxative doses of magnesium products are typically much higher and are intended for short-term use only. Talk to a clinician or pharmacist before starting magnesium citrate, especially if you take other medications, have kidney problems, or are pregnant.

Magnesium naturally present in food and beverages is not considered harmful in healthy people, because the kidneys clear any excess in the urine. Supplemental magnesium, however, can accumulate to harmful levels in people with reduced kidney function, and MedlinePlus notes that magnesium excess most often results from supplements or magnesium-containing laxatives rather than from food. According to the NIH, extremely high intakes can lead to irregular heartbeat and, in extreme cases, cardiac arrest; the health-professional fact sheet also describes signs of magnesium toxicity such as low blood pressure, nausea and vomiting, facial flushing, lethargy, and difficulty breathing. Anyone with kidney disease, a heart condition, or who is pregnant or breastfeeding should consult a clinician before use.

The most common effects of too much supplemental magnesium are diarrhea, nausea, and abdominal cramping — and because magnesium citrate works as an osmotic laxative, loose stools are an expected effect at laxative doses. These gastrointestinal effects are the reason the supplemental upper limit is set at 350 mg/day for adults. Far more serious effects, such as irregular heartbeat and cardiac arrest, occur only with extremely high intakes or impaired kidney function.

The NIH lists several drug interactions. Magnesium can reduce absorption of oral bisphosphonates (osteoporosis drugs), which the health-professional fact sheet says should be separated from magnesium by at least 2 hours. It can also bind tetracycline and quinolone antibiotics (such as doxycycline, ciprofloxacin, and levofloxacin), which per the NIH should be taken at least 2 hours before or 4-6 hours after a magnesium supplement. Proton pump inhibitors used long term can lower blood magnesium levels, and diuretics can change how much magnesium is lost in the urine — loop and thiazide diuretics in particular can increase magnesium loss. Review all medications with a pharmacist or clinician before combining them with magnesium citrate.