Vitamin B12 deficiency: what to watch for and what to do

Feeling tired all the time, getting pins-and-needles in your hands, or noticing memory problems? Those can be signs of vitamin B12 deficiency. B12 helps your nerves and makes red blood cells. When it’s low, your body shows it fast in energy, mood, and nerve symptoms. This page gives straight, practical steps you can use today.

Common causes and who’s at risk

Low B12 happens for a few clear reasons. Not eating animal foods (vegans) is one. Problems that stop your gut from absorbing B12 — like pernicious anemia, gastric surgery, celiac disease, or long-term use of proton pump inhibitors (PPIs) — are another. Certain drugs, especially metformin for diabetes, can lower B12 over time. Older adults also absorb less B12 as they age. If you’re pregnant and avoid animal products, your baby can be affected too.

Quick checklist: check B12 if you’re vegan, over 60, on metformin or PPIs, had stomach surgery, or have unexplained fatigue, numbness, or memory issues.

How it’s diagnosed and treated

Your doctor usually orders a complete blood count (CBC) and a serum B12 level. If results are borderline, tests for methylmalonic acid (MMA) or homocysteine give a clearer picture — both rise when B12 is low. For suspected pernicious anemia, doctors test for intrinsic factor antibodies.

Treatment choices depend on cause and severity. If absorption is the problem, injections of B12 (often 1,000 mcg) are common at first — usually weekly until levels and symptoms improve, then monthly. Many people respond quickly: energy and blood counts often improve within weeks; nerve recovery can take months. For people who can absorb some B12, high-dose oral supplements (1,000–2,000 mcg daily) work well. There’s also an intranasal option for maintenance.

Small, practical tips: if you take metformin, ask for a B12 check every year. Vegans should use B12 supplements or fortified foods — a daily 25–100 mcg supplement or 1,000 mcg weekly (cyanocobalamin or methylcobalamin) keeps levels safe for most people. If you have neurological symptoms, don’t delay testing — early treatment prevents long-term damage.

A quick note on folate: high folate can hide B12 deficiency on some tests. If symptoms fit but B12 looks normal, ask about MMA or homocysteine tests. Monitor treatment with a repeat blood test after a few months and track symptom improvement.

Got symptoms or risk factors? Talk to your doctor and ask for a B12 screen. It’s a simple blood test and, if needed, treatment is straightforward and effective. Keeping tabs on B12 is one of the easiest ways to protect your energy, brain, and nerves.