Magnesium deficiency: symptoms, tests and which form to choose

About 50% of Europeans consume less magnesium than the recommended daily intake. Chronic subclinical deficiency is one of the most commonly undiagnosed metabolic problems – because serum magnesium only flags a deficiency once intracellular levels have already dropped substantially.

Why magnesium is critical

Magnesium is a cofactor in > 300 enzymatic reactions: ATP production, DNA synthesis, calcium and potassium balance, insulin signalling. DiNicolantonio et al. (Open Heart, 2018) call subclinical magnesium deficiency an underrated driver of cardiovascular disease.

Symptoms

• Muscle cramps (especially at night), eyelid twitch
• Fatigue, low stress tolerance
• Insomnia, difficulty falling asleep
• Palpitations, ectopic beats
• Constipation
• Headaches and migraine
• PMS and painful periods
• High blood pressure

Tests

Serum magnesium reflects only 1% of total body magnesium. Better: RBC magnesium (red blood cell). The literature discusses 6.0–6.5 mg/dL as more favourable, while lab reference ranges are wider (4.2–6.8); this is an educational, not a diagnostic, cutoff.