Vitamin B12 Deficiency: Signs, Risk Groups and Testing

B12 deficiency is one of the more common reversible causes of neurological symptoms, and it is also one of the more frequently missed.

What deficiency does

B12 is required for myelin maintenance and for DNA synthesis. Deficiency produces two broad pictures that do not always appear together. Haematologically it causes megaloblastic anaemia with characteristically large red blood cells. Neurologically it causes peripheral neuropathy and, if prolonged, subacute combined degeneration of the spinal cord. Critically, neurological damage can occur without anaemia, which is one reason a normal full blood count does not rule deficiency out.

Who is at risk

Adults over fifty, because reduced stomach acid impairs release of B12 from food proteins. People on long-term metformin, which reduces absorption. People on long-term proton pump inhibitors or H2 blockers. People who have had gastric or ileal surgery, including bariatric procedures. People with pernicious anaemia, coeliac disease or Crohn's disease. And people eating strict plant-based diets without supplementation, since B12 is not reliably available from plant foods.

Testing and the folate complication

Serum B12 is the usual first test, though it has limitations at borderline values, where methylmalonic acid and homocysteine can clarify the picture. The important complication is folate: high folate intake can correct the anaemia of B12 deficiency while neurological damage continues unaddressed. This is why folic acid fortification made clinical vigilance about B12 more rather than less important, and why guessing rather than testing is a poor idea when symptoms are neurological.

How this relates to NeuronGold

NeuronGold works through nutrient support rather than through any acute stimulant effect, which means it is not designed to produce a same-day change. Our 30-day assessment guide explains how to test it properly against a recorded baseline. Current NeuronGold discount pricing is applied automatically by quantity on the order page.