Magnesium Deficiency

Magnesium sits inside cells and bone; less than 1% of body magnesium circulates in serum, and the body defends that number tightly by pulling from bone. That is why a normal serum magnesium result does not exclude depletion, and why chronic subclinical insufficiency is common while frank hypomagnesaemia is comparatively rare. Roughly half of adults in western countries consume less than the recommended intake, largely because magnesium lives in foods people eat less of: leafy greens, legumes, nuts, seeds and whole grains. Certain situations deplete magnesium reliably rather than probabilistically — long-term proton pump inhibitor use, loop and thiazide diuretics, chronic alcohol use, poorly controlled diabetes with osmotic diuresis, and malabsorptive gut disease. Symptoms are non-specific: muscle cramps and twitching, particularly eyelid fasciculation, fatigue, irritability, poor sleep and palpitations. Severe depletion causes tetany, arrhythmias and refractory hypokalaemia — potassium cannot be corrected until magnesium is. For repletion the form matters more than the dose. Magnesium oxide is cheap but poorly absorbed and mostly acts as a laxative; glycinate, citrate and malate are far better tolerated and absorbed. Doses above 350mg of elemental magnesium from supplements commonly cause diarrhoea.

• •Muscle cramps and eyelid twitching
• •Fatigue and low energy
• •Poor sleep and restlessness
• •Irritability or low mood
• •Palpitations
• •Constipation

• •Diet low in greens, legumes, nuts and whole grains
• •Proton pump inhibitors
• •Loop and thiazide diuretics
• •Chronic alcohol use
• •Type 2 diabetes with high blood glucose
• •Malabsorptive gut disease

Low dietary intake from refined food patterns, proton pump inhibitor and diuretic use, chronic alcohol intake, poorly controlled diabetes, malabsorption from coeliac or inflammatory bowel disease, and increased losses through heavy sweating or vomiting.