Magnesium supplements that dissolve easily in liquid are better than supplements that are less soluble, because the stomach absorbs them more readily, reports the National Institutes of Health. Studies show that lactate, chloride, citrate and aspartate forms of magnesium absorb better than magnesium sulfate or magnesium oxide. Although the body eliminates excess magnesium from food via urine, consumers should avoid magnesium supplements that contain more than the maximum daily recommended amount, because of possible side effects.
For healthy individuals, the maximum recommended daily intake of magnesium through supplements is 65 milligram for children one to three years old, 110 milligrams for children four to eight years old, and 350 milligrams for everyone age nine and over, according to the National Institutes of Health. Symptoms of excessive magnesium supplement intake may include diarrhea, stomach cramps and nausea. Extremely excessive amounts can cause vomiting, difficulty breathing, irregular heartbeat, heart failure and even death. Some medicines, such as antibiotics and diuretics, do not react well with magnesium, and consumers should not take them at the same time that they take magnesium supplements.
Many people can get their recommended daily allowance of magnesium through foods such as green leafy vegetables, legumes, seeds, nuts and whole grains, explains the National Institutes of Health. People who may experience magnesium deficiency include type 2 diabetics, the elderly, alcohol dependent individuals and those with gastrointestinal diseases.