
Introduction
Magnesium is the fourth most common mineral in the human body after calcium, sodium, and potassium and is involved in more than 300 enzymatic processes in the body. [1,2,6]
It also plays a role in the maintenance of intracellular levels of potassium and calcium. [1,2,5]
Research indicates that newborns have 760mg of magnesium at birth, about 5g at 4-5 months and 25g in adulthood. [2]

- Magnesium is absorbed along the entire intestinal tract, with maximum absorption occurring at the distal jejunum and ileum. [3]
- Approximately 30-40% of the magnesium consumed from food is absorbed by the body. [1,3]
- Magnesium absorption is inversely proportional to the amount of magnesium consumed. [3]
- Ageing reduces absorption by 30% or so. [6]

- The total magnesium content in a healthy individual is estimated to be around 20-28g [7].
- Almost 50-60% of the magnesium in the human body is stored in the bones and the rest is in soft tissues and muscles. [1,6]
- Less than 1% is in blood serum and these levels are kept under tight control and the biological half-life of magnesium in the body is about 1000 hours (42 days). [1,6]

- The kidney sregulates the magnesium content in the body and limits urinary excretion in case of deficient levels. [1]
- Approximately, 12o mg of magnesium is excreted every day. [1]
- Also, smoking cigarettes reduces plasma magnesium concentration. [6]
Body Functions

Recommended Daily Intake

Deficiency Symptoms

Magnesium Food Sources

Excessive Intake/ Toxicity Side Effects

Groups At Risk of Magnesium Deficiency
Magnesium Interaction With Other Nutrients
- Protein – Magnesium absorption is lower when protein intake is less than 30g/day. [3,4] A higher protein intake may increase renal magnesium excretion, perhaps because an increased acid load increases urinary magnesium excretion. [3]
- Zinc – High intakes of zinc (142 mg/day) in supplemental form may decrease magnesium absorption. [2,4]
- Vitamin D – The active form of vitamin D appears to enhance intestinal magnesium absorption, to a small extent[3,4].
- Phosphorus – Phosphorus may decrease magnesium absorption, phosphates binding to magnesium may explain decreases in intestinal magnesium absorption. [3]
- Calcium and Sodium – High calcium intakes (2600 mg/day) accompanied with high sodium intakes may contribute towards negative magnesium balance increasing its urinary output. [2,3]
- Fibre and Phytic acid – High intakes of dietary fibre (40–50 g/day)which contains phytic acid lowers magnesium absorption probably due to bindings of phosphate groups on phytic acid. [2,3,4]