Doctor-written guides to vitamin and mineral levels, from vitamin D and B12 to magnesium and zinc. Signs of deficiency and what your result means.
Zinc deficiency is easy to overlook, yet this small trace mineral runs an enormous number of jobs — from defending you against infections to healing wounds and keeping your sense of taste sharp. Because your body has no large store of zinc, a shortfall can build quietly and show up in surprisingly varied ways. This…
Your potassium levels rarely make headlines, but few numbers on a blood test matter more for your heart. Potassium is an electrolyte — a mineral that carries an electrical charge — and your body keeps it within a remarkably narrow range, because both too little and too much can disturb your heartbeat. This guide explains…
Magnesium is one of the hardest-working minerals in your body, involved in hundreds of processes — yet a deficiency is common and surprisingly easy to miss. It can show up as muscle cramps, poor sleep, fatigue, or anxiety, and a routine blood test doesn’t always catch it. So what are the signs of magnesium deficiency,…
Quick answer Most B12 blood tests measure total B12 (serum cobalamin). UK guidance (NICE, 2024) reads below 180 ng/L (133 pmol/L) as confirmed deficiency, 180–350 ng/L as indeterminate, and above 350 ng/L (258 pmol/L) as deficiency unlikely. A 2025 US review uses the same cut-offs in pg/mL, with a methylmalonic acid (MMA) test in between….
Quick answer Vitamin D levels are measured as 25-hydroxyvitamin D, or 25(OH)D. UK guidance calls below 25 nmol/L deficient, says 25–50 nmol/L may be inadequate for some people, and treats above 50 nmol/L as sufficient. US guidance (National Academy of Medicine) links below 12 ng/mL to a risk of deficiency and calls 20 ng/mL or…