DR. SABBU KISHORE outlines the widespread yet often overlooked impact of vitamin B12 deficiency on neurological health, cardiovascular risk, and overall well-being.
Vitamin B12 deficiency is quietly becoming one of the most widespread nutritional deficiencies worldwide, particularly in India. Despite being essential for brain function, nerve health, blood formation, and heart protection, it often goes unnoticed until significant damage has already occurred. Many people live for years with low vitamin B12 levels without realizing that their fatigue, memory problems, or tingling sensations have a nutritional cause.
How Widespread Is the Problem?
Nearly one in three to one in two Indian adults have low or borderline B12 levels. The problem is not limited to the elderly; young professionals, students, and adolescents are now affected as well. Modern diets, stress, digestive problems, and long-term medications drive this trend.
Who Is Most at Risk?
B12 is found in animal-based foods. Vegetarians and vegans are especially at risk. Older adults, people with diabetes on metformin or acid-suppressing drugs, those with gut disorders, alcohol use, pregnancy, or chronic stress, also have a higher risk.
Why Vitamin B12 Is So Vital
Vitamin B12 is crucial for the production of red blood cells and for the protection of nerves through the myelin sheath. It supports brain health, memory, mood, and energy. A vital function is controlling homocysteine, which can damage blood vessels if too high.
Homocysteine: The Hidden Link to Stroke
When vitamin B12 levels are low, homocysteine accumulates in the blood. Elevated homocysteine damages the inner lining of blood vessels, increases clot formation, and accelerates hardening of the arteries. This significantly raises the risk of stroke and heart disease, sometimes even in young individuals who do not have traditional risk factors such as diabetes, high blood pressure, or smoking.
Neurological Symptoms: Often the First Warning Sign
Neurological symptoms can appear before anemia. These may include tingling, numbness, burning, balance issues, fatigue, poor memory, mood changes, depression, and sleep problems. If untreated, permanent nerve and cognitive damage may result.
Vitamin B12 is crucial for making red blood cells and
protecting nerves through the myelin sheath.
It supports brain health, memory, mood, and energy.
A vital function is controlling homocysteine,
which can damage blood vessels if too high.
Why B12 Deficiency Is Frequently Missed
A normal hemoglobin level does not rule out a vitamin B12 deficiency. B12 deficiency can occur even with normal blood counts. Symptoms are often dismissed as stress, aging, or lifestyle, allowing the deficiency to worsen unnoticed.
The Right Way to Check Vitamin B12 Status
A simple blood test detects low B12 levels, but the results need careful interpretation. Symptoms may appear even at low-normal values. Measuring serum homocysteine is helpful, as elevated levels indicate functional deficiency and increased vascular risk. MMA testing can help confirm cellular B12 deficiency, particularly with borderline results.
Correcting the Deficiency
Treatment depends on the severity of the deficiency and the presence of symptoms. Mild to moderate deficiency can often be corrected with high-dose oral or sublingual vitamin B12 supplementation, preferably in the form of methyl cobalamin. In individuals with severe deficiency or neurological symptoms, vitamin B12 injections are recommended initially, followed by long-term maintenance therapy. Correction of associated folate and vitamin B6 deficiencies is also important to normalize homocysteine levels.
Prevention Is Better Than Cure
Regular screening is key to prevention. Elderly, vegetarians, people with diabetes, and those on long-term medication need periodic B12 and homocysteine tests. Awareness helps, but supplements are often essential.
The Take-Home Message
Vitamin B12 deficiency is common, silent, and serious, affecting energy, brain, nerves, and blood vessels. Elevated homocysteine connects it to stroke and heart disease. Early detection and treatment can reverse symptoms and prevent harm. Paying attention to B12 now protects future health.
Vitamin B12 deficiency is common, silent, and serious,
affecting energy, brain, nerves, and blood vessels.
Elevated homocysteine connects it to stroke and heart disease.
Early detection and treatment can reverse symptoms
and prevent harm. Paying attention to B12 now protects future health.
References:
1. Green R, et al. Vitamin B12 deficiency. Nat Rev Dis Primers. 2017.
2. Comprehensive review on prevalence, clinical features, and diagnosis of B12 deficiency.
3. Hamza Ali et al. The Neurological Sequelae of Vitamin B12 Deficiency: A Systematic Review and RCT. PubMed. 2025.
Focuses on neurological outcomes and treatment effects in B12 deficiency.
4. Mahalle N, et al. Vitamin B12 deficiency and hyperhomocysteinemia as correlates of cardiovascular risk factors (Indian CAD patients). J Cardiol. 2013.
5. Shows high prevalence of B12 deficiency and elevated homocysteine in cardiovascular disease.
6. Metabolic vitamin B12 deficiency: a missed opportunity to prevent dementia and stroke (Narrative Review). PubMed. 2015.
Discusses metabolic B12 deficiency, stroke risk, and the importance of functional markers (MMA, homocysteine).
7. Role of vitamin B12 deficiency in ischemic stroke risk and outcome (Review). PubMed. 2020.
Reviews evidence linking B12 deficiency to ischemic stroke and mechanisms, including homocysteine elevation.
8. Serum Vitamin B12 Levels as a Risk Factor and Prognostic Marker in Acute Ischemic Stroke (Case-control, India). PubMed. 2025.
9. Demonstrates lower B12 and higher homocysteine in stroke patients with worse outcomes.
10. Homocysteine, B vitamins, and cardiovascular disease: a Mendelian randomization study. BMC Med. 2021.
Genetic evidence linking homocysteine levels to stroke risk, highlighting the role of B vitamins.
11. Neurological disorders in vitamin B12 deficiency (Review). PubMed.
Details the spectrum of neurologic manifestations, including peripheral neuropathy, myelopathy, and cognitive issues.
12. Association between neuropathy and B-vitamins: Systematic Review and Meta-analysis. PubMed. 2021.
Meta-analytic evidence linking low B12 (and elevated homocysteine/MMA) with peripheral neuropathy.
13. Vitamin B12 Deficiency-Induced Neuropathy and Cognitive and Motor Impairment in the Elderly: Case Reports. PubMed. 2025.
Case evidence highlighting diagnostic challenges and the utility of homocysteine/MMA testing even with “normal” serum B12.
Sabbu Kishore
Dr. Sabbu Kishore (DCH, MD Internal Medicine) is a Diplomate of the American Board of Lifestyle Medicine and Director of Kanha Medical and Research Centre. He is also a certified Heartfulness trainer, supporti... Read More
