Magnesium is found naturally in many foods. In general, foods containing dietary fiber provide magnesium. Green leafy vegetables, such as spinach, as well as legumes, nuts, seeds, and whole grains, are all good sources. Meats and milk have intermediate magnesium content, whereas refined foods generally have the lowest content. Another good source of magnesium is water (tap, bottled, or mineral).
It's also worth noting that the levels of magnesium in food depend on the levels found in the soil in which it is grown. Avoid commercially farmed foods—because pesticides and fertilizers often deplete the soil of its magnesium. Organic farming with good crop rotation produces food with the highest levels of magnesium.
Magnesium supplements come in many forms. Magnesium citrate, glycinate taurate, or aspartate are the best forms for supplementation because they have the highest absorption rate. Avoid magnesium carbonate, magnesium sulfate, magnesium gluconate, and magnesium oxide, because the body absorbs them poorly. Magnesium stearate, another supplement, does not contain magnesium for the body; rather, it is a compound created for supplement manufacturing. Check multivitamin labels, too, because many contain only a small amount of magnesium—in which case you'll need to add pure magnesium to your supplement regimen.
Maintaining the proper level of magnesium is central to a healthy lifestyle. The body will indicate whether too much magnesium is consumed through food; common side effects of overconsumption include diarrhea and nausea. Magnesium can interact with medications, so be sure to consult a healthcare professional before taking a magnesium supplement.