Most Americans do not get enough magnesium in their diets, but this doesn't mean you should rush into taking a magnesium supplement, advises the Office of Dietary Supplements. It's best to get this nutrient naturally through foods. Your body only absorbs 30 percent to 40 percent of the magnesium you eat, but fortunately this nutrient is found in a variety of plant and animal sources, making it easy to increase your intake naturally. Supplements can lead to symptoms of magnesium toxicity and be detrimental to heart and kidney patients.
Magnesium's Role in the Body
Your body needs magnesium for functions such as protein synthesis, muscle and nerve function, blood sugar maintenance and blood pressure control. You also require it to produce energy, as well as for healthy bones and teeth. You get dietary magnesium from nuts, including almonds, cashews and peanuts, as well as spinach, soy milk, beans, edamame, whole grains, avocado, yogurt, salmon, bananas, raisins, chicken breast and lean ground beef. The recommended dietary allowance of magnesium is 400 milligrams for males 19 to 30 years old and 420 milligrams for males over 30. The RDA for females 19 to 30 years is 310 milligrams and 320 for females over 30. Adults should not take a supplement containing more than 350 milligrams of this nutrient.
Symptoms of Magnesium Overdose
It's uncommon to get too much magnesium from foods, says the University of Maryland Medical Center, but it's possible to overdose through supplements, which include the magnesium found in laxatives, antacids and Epsom salts. The most commonly reported side effects of magnesium toxicity are an upset stomach and diarrhea. It can also cause nausea, vomiting, severely low blood pressure, confusion and lowered heart rate. Severe cases of magnesium overdose can result in coma, heart and respiratory problems and even death. Magnesium also competes with other minerals for absorption into your body, such as calcium, so too much magnesium can cause a deficiency in other minerals.
Harmful for Kidney Patients
Your kidneys excrete excess magnesium from your body. If you suffer from renal problems or kidney failure, your kidneys are unable to get rid of the extra magnesium. Magnesium builds up to dangerous levels, leading to symptoms of toxicity. Therefore, MedlinePlus recommends not taking a magnesium supplement if you suffer from kidney problems. The University of Maryland Medical Center warns heart patients to take magnesium supplements only under the supervision of your doctor because of the same inability for your kidneys to excrete extra magnesium.
Always check with your doctor if you are taking medication before starting a magnesium supplement. Several medications interact with the supplement or can affect your magnesium levels. Magnesium inhibits the absorption of some antibiotics and osteoporosis medications. Certain diuretics decrease how much magnesium you excrete, which can lead to toxic levels if you take a magnesium supplement. MedlinePlus states that magnesium lowers blood pressure and relaxes muscles. If you're on blood-pressure-lowering medication, your blood pressure may get too low, and if you take muscle relaxants, you increase your risk for side effects of that medication.