Magnesium citrate

Magnesium citrate is a compound formed by combining magnesium with citric acid. When dissolved in water it releases magnesium ions and citrate, giving it a tart taste. In nutrition it serves as a source of magnesium and is often used as a mild laxative or acidity regulator.

Physiological role of magnesium

Magnesium is the fourth most abundant mineral in the body. About half is stored in bone, with the rest inside cells where it acts as a cofactor for hundreds of enzymes involved in energy production, protein synthesis and muscle contraction. It helps control nerve impulses and supports the transport of calcium and potassium across cell membranes. Without adequate magnesium, muscles may cramp and nerves become excitable. Magnesium citrate dissolves readily and is considered more bioavailable than some other forms, making it a popular supplement. However, sweat losses of magnesium during exercise are small compared with sodium or chloride, so only modest amounts are needed in a rehydration drink. A varied diet containing whole grains, nuts, seeds, legumes and leafy green vegetables usually provides the recommended 300–400 mg per day.

Uses and cautions

Magnesium citrate is widely sold as an over-the-counter laxative because the poorly absorbed magnesium draws water into the intestine. It is also added to some sports drinks and oral rehydration solutions as a magnesium source and acidity regulator, identified as food additive E345. Natural food sources such as almonds, pumpkin seeds, spinach, beans and whole grains deliver much more magnesium than sports beverages. People with kidney disease or those taking certain medications should consult a healthcare professional before consuming extra magnesium, because high doses can lead to diarrhoea, low blood pressure or irregular heartbeat. For most athletes and recreational exercisers, magnesium requirements are met through regular meals, and supplementation with magnesium citrate is unnecessary unless a deficiency has been diagnosed.

Magnesium citrate offers a bioavailable form of magnesium that can help regulate acidity in drinks. In sports hydration its role is secondary to replacing sodium and fluids, and a balanced diet remains the best way to maintain adequate magnesium levels.

Related Terms: potassium citrate, sodium citrate, calcium chloride, hydration, rehydration