Vitamin B12 Deficiency: A Correctable Cause

This is the single most important nutritional cause of cognitive symptoms because it is common, serious and correctable.

What deficiency does

B12 is required for myelin maintenance and for one-carbon metabolism. Deficiency causes megaloblastic anaemia and, separately, neurological effects including peripheral neuropathy, subacute combined degeneration of the spinal cord, cognitive impairment and mood changes. Critically, neurological symptoms can occur without anaemia, so a normal full blood count does not exclude it — a point that has caused missed diagnoses.

Who is at risk

Older adults, in whom absorption declines with reduced stomach acid. People on long-term metformin, which reduces absorption. People on long-term proton pump inhibitors or H2 blockers. People with pernicious anaemia, coeliac disease, Crohn's disease or after gastric surgery. Vegans and vegetarians, since B12 is essentially absent from plant foods — supplementation or fortification is mandatory rather than optional on a fully plant-based diet.

Testing and treatment

Serum B12 is the standard test but has limitations, and borderline results may warrant methylmalonic acid or homocysteine testing, both of which rise in functional deficiency. Treatment is straightforward — oral high-dose or injections depending on cause. Neurological recovery is better with earlier treatment and may be incomplete if deficiency has been prolonged, which is the argument for testing rather than waiting. Anyone with memory complaints should have B12 checked before buying a cognitive supplement.

Cognicept in context

Nothing on this page is a claim about Cognicept specifically. Cognicept is a dietary supplement providing nutritional support for memory and focus; it is not a treatment for memory loss, dementia, anxiety or cognitive decline. Persistent or worsening memory symptoms warrant medical assessment, because several causes are checkable and correctable. For an honest read on the money, our value for money review states both sides.