Table 1 lists the current RDAs for magnesium. Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them can also be used to assess the nutrient intakes of individuals.Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy established when evidence is insufficient to develop an RDA.Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%вЂ“98%) healthy individuals often used to plan nutritionally adequate diets for individuals.These values, which vary by age and sex, include: DRI is the general term for a set of reference values used to plan and assess nutrient intakes of healthy people. Intake recommendations for magnesium and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences). To comprehensively evaluate magnesium status, both laboratory tests and a clinical assessment might be required. Some experts but not others consider the tolerance test (in which urinary magnesium is measured after parenteral infusion of a dose of magnesium) to be the best method to assess magnesium status in adults. No single method is considered satisfactory. Other methods for assessing magnesium status include measuring magnesium concentrations in erythrocytes, saliva, and urine measuring ionized magnesium concentrations in blood, plasma, or serum and conducting a magnesium-loading (or 'tolerance') test.

The most commonly used and readily available method for assessing magnesium status is measurement of serum magnesium concentration, even though serum levels have little correlation with total body magnesium levels or concentrations in specific tissues. ДЄssessing magnesium status is difficult because most magnesium is inside cells or in bone. Urinary excretion is reduced when magnesium status is low. Magnesium homeostasis is largely controlled by the kidney, which typically excretes about 120 mg magnesium into the urine each day. Hypomagnesemia is defined as a serum magnesium level less than 0.75 mmol/L. Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles (mmol)/L. Less than 1% of total magnesium is in blood serum, and these levels are kept under tight control. ДЄn adult body contains approximately 25 g magnesium, with 50% to 60% present in the bones and most of the rest in soft tissues.

Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm. It contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. Magnesium is required for energy production, oxidative phosphorylation, and glycolysis. Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium, an abundant mineral in the body, is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). For a reader-friendly overview of Magnesium, see our consumer fact sheet on Magnesium. This is a fact sheet intended for health professionals.

Best form of magnesium for absorption