Magnesium Citrate

Magnesium citrate is the workhorse of magnesium supplements - well-absorbed, inexpensive, and backed by decades of use. It is the second most common magnesium supplement after glycinate, and for most people who want general magnesium replenishment at a reasonable cost, it is a solid choice. The citrate form has better bioavailability than magnesium oxide (the cheap form in many multivitamins) and is reasonably close to magnesium glycinate in absorption, at lower cost.

The evidence base for magnesium citrate is largely shared with magnesium supplementation broadly. The blood pressure, blood sugar, sleep, and bone health benefits seen in meta-analyses apply to magnesium generally when correction of deficiency is the mechanism. A 2003 study by Walker et al. in the Journal of the American College of Nutrition directly compared citrate and oxide forms, confirming citrate had significantly better absorption and urinary excretion (a marker of bioavailability).

The one area where citrate distinguishes itself from glycinate is its mild laxative effect. Magnesium citrate draws water into the intestines and stimulates peristalsis. At standard supplemental doses (200-400mg elemental), this effect is mild - just a softer stool for most people. At the high doses used in medical colonoscopy prep (a full bottle at 1,750mg elemental), it is a powerful osmotic laxative. This means citrate is genuinely useful for people who have both magnesium deficiency and constipation issues - two birds, one supplement. It also means people with loose stools or IBS-D should consider glycinate instead.

Where citrate falls short of glycinate: the glycine amino acid in glycinate has independent calming and sleep-promoting effects that citrate lacks. For people specifically targeting sleep quality or anxiety alongside magnesium deficiency, glycinate remains the better choice. But for budget-conscious general supplementation, magnesium citrate is hard to beat.