Vitamin B12 Deficiency: Are Your Symptoms Trying to Tell You Something?

Written by Kristy Beard, MSN, APRN, FNP-C — Board-Certified Family Nurse Practitioner and Founder of Elevate Health and Wellness, serving patients across the Gulf Coast in Gautier, MS and Foley, AL.

The Many Faces of B12 Deficiency

Vitamin B12 deficiency is a clinical chameleon — producing symptoms that span neurology, hematology, psychiatry, and general medicine, and that can develop so gradually that patients adapt to their declining function without recognizing that something is wrong. At Elevate Health and Wellness, Kristy Beard, MSN, APRN, FNP-C identifies B12 deficiency regularly in patients who present with complaints ranging from fatigue and cognitive decline to peripheral neuropathy and unexplained anemia — conditions that may have been evaluated repeatedly without the underlying nutritional deficiency being identified.

Why B12 Deficiency Is So Often Missed

Several factors contribute to B12 deficiency being chronically underdiagnosed. Standard reference ranges for serum B12 vary by laboratory but typically define deficiency as below 200 pg/mL. However, research published in the American Journal of Hematology and supported by functional medicine literature suggests that neurological symptoms of B12 deficiency can occur at levels between 200 and 400 pg/mL — values that fall within the normal reference range of most laboratories. This means patients can have clinically significant B12 insufficiency with a serum level that is not flagged as abnormal. At Elevate, Kristy evaluates B12 in the context of symptoms and may also order methylmalonic acid (MMA) and homocysteine — more sensitive functional markers of B12 status — when clinical suspicion is high despite a normal serum level.

Who Is Most at Risk for B12 Deficiency

Adults over 50 are at significantly increased risk because gastric acid production — which is essential for releasing B12 from food proteins — declines with age. Patients taking proton pump inhibitors (PPIs) for acid reflux or metformin for blood sugar management are at substantially elevated risk, as both medications impair B12 absorption. Vegetarians and vegans consume no animal products — the primary dietary source of B12 — and are at high risk without supplementation. Anyone with a history of gastrointestinal surgery, celiac disease, Crohn's disease, or other conditions affecting gastric or small intestinal function may have impaired B12 absorption regardless of adequate dietary intake.

Recognizing the Symptoms

The neurological symptoms of B12 deficiency include peripheral neuropathy with tingling, numbness, or burning in the hands and feet; difficulty with balance and coordination; cognitive changes including memory impairment, difficulty concentrating, and slowed processing speed; and in severe cases, subacute combined degeneration of the spinal cord. Psychiatric manifestations include depression, irritability, and in severe cases psychosis. Hematological symptoms include megaloblastic anemia producing fatigue, weakness, and pallor. General symptoms include fatigue, reduced exercise tolerance, and glossitis (a smooth, painful tongue). Because B12 is stored in the liver, significant deficiency takes months to years to develop — and symptoms may appear insidiously.

Think you might be B12 deficient? Learn about our nutritional health and lab services at Elevate in Gautier, MS and Foley, AL.

Sources: American Journal of Hematology. B12 Deficiency and Neurological Symptoms. onlinelibrary.wiley.com. | NIH. Vitamin B12 Fact Sheet. ods.od.nih.gov.

This article is written by Kristy Beard, MSN, APRN, FNP-C, board-certified Family Nurse Practitioner and founder of Elevate Health and Wellness. Information provided is for educational purposes only and does not constitute medical advice. Please consult a licensed healthcare provider for personalized care.