Magnesium is involved in over 300 enzymatic reactions in the human body — including ATP production, protein synthesis, DNA repair, nerve transmission, muscle contraction, and blood glucose regulation. It is the fourth most abundant mineral in the body and the most common micronutrient deficiency in the developed world. Yet it is also one of the most frequently under-supplemented, partly because the variety of forms and claims creates confusion.
Why Deficiency Is So Common
Several converging factors drive widespread magnesium insufficiency: modern intensive farming has depleted magnesium from soil, reducing food content; food processing removes up to 80% of magnesium; the modern Western diet is low in the primary magnesium sources (dark leafy greens, legumes, nuts, seeds, wholegrains); chronic stress increases urinary magnesium excretion significantly; alcohol, coffee, and many medications (PPIs, diuretics, metformin) further deplete stores. Serum magnesium tests are poorly sensitive (only about 1% of total body magnesium is in blood) — intracellular deficiency is common with normal serum levels. Erythrocyte or RBC magnesium testing is more sensitive.
What Magnesium Supplementation Genuinely Helps
Sleep quality: magnesium modulates GABA receptors (promoting relaxation) and NMDA receptors (reducing hyperarousal). Multiple RCTs show improved sleep quality, sleep onset, and sleep duration, particularly in older adults. Anxiety and stress: GABA-A receptor modulation has genuine anxiolytic effects; RCTs show modest but consistent anxiety reduction. Muscle cramps and spasms: including nocturnal leg cramps and exercise-related cramps — not universally effective but beneficial in deficient individuals. Migraine prevention: strong evidence; 400–600mg daily reduces migraine frequency by approximately 40% in multiple RCTs. Blood pressure: modest reduction in both systolic and diastolic in those who are deficient or hypertensive. Blood glucose and insulin sensitivity: magnesium is an essential cofactor for insulin receptor signalling; supplementation improves insulin sensitivity in deficient people.
Forms of Magnesium: Which to Choose
Magnesium glycinate: highest bioavailability and best tolerated; magnesium bound to glycine (a calming amino acid); best choice for sleep, anxiety, and general supplementation. Magnesium malate: good bioavailability; malate supports ATP production; best for energy and muscle fatigue. Magnesium citrate: good bioavailability; has a mild laxative effect; useful for those with constipation. Magnesium L-threonate: specifically crosses the blood-brain barrier; emerging evidence for cognitive benefits; expensive but unique for brain applications. Magnesium oxide: poorest bioavailability (~4%); primarily laxative; avoid for systemic supplementation. Dose: 200–400mg elemental magnesium daily, taken in the evening (supports sleep).
Frequently Asked Questions About Magnesium
Can I get enough magnesium from food?
Theoretically yes — dark leafy greens (100mg per 100g cooked spinach), pumpkin seeds (150mg per 30g), legumes, wholegrains, and dark chocolate are rich sources. In practice, many people consistently fall short. If diet is reliably rich in these foods, supplementation may not be needed. If you eat a typical Western diet, are under chronic stress, or exercise heavily, supplementation is worthwhile.
Can you take too much magnesium?
At oral supplement doses, excess magnesium is excreted renally — the main symptom of excess is loose stools/diarrhoea (which is actually used therapeutically as a laxative). Genuine toxicity requires very high doses or impaired renal function. In people with kidney disease, high magnesium supplementation is contraindicated — discuss with a GP.
Browse magnesium supplements including glycinate and citrate at Huncoat Pharmacy. Related: Sleep Quality, Anxiety.
At Huncoat Pharmacy: Magnesium IV infusion service, Browse magnesium supplements.