A recent advisory by an Apollo Hospitals neurologist has drawn attention to an often-overlooked concern: the effect of certain common medications on vitamin B₁₂ absorption. According to a recent video shared by Dr Sudhir Kumar, MD, a senior neurologist at Apollo Hospitals in Hyderabad, two widely prescribed drugs, Metformin, used for type 2 diabetes, and Proton Pump Inhibitors (PPIs), used to treat acid reflux, can interfere with how the body absorbs vitamin B₁₂.
He suggested that people using metformin for a long time should stay alert to symptoms that might signal a vitamin B₁₂ deficiency. These can show up as persistent tiredness, tingling or numbness in the hands and feet, or subtle cognitive issues such as forgetfulness, low mood, or difficulty concentrating. Scientific studies support this observation and highlight the need for regular monitoring, especially in long-term users.[1]
How these medicines affect absorption of vitamin B₁₂
Vitamin B₁₂ from food binds to proteins. When food reaches the stomach, acid and digestive enzymes release it, allowing it to attach to a protein called intrinsic factor. This complex is then absorbed in the small intestine.[2]
When acid-reducing drugs such as PPIs are taken for prolonged periods, the stomach produces less acid. As a result, vitamin B₁₂ is not efficiently released from food, leading to lower absorption. On the other hand, metformin appears to interfere with the vitamin’s absorption in the lower intestine, possibly by altering calcium-dependent transport mechanisms.[2]
If both drugs are used together, their effects can add up, increasing the likelihood of deficiency.
What the studies reveal about vitamin B₁₂
A 2025 review published in the Egyptian Journal of Internal Medicine found that prolonged use of PPIs, H₂-blockers, and metformin is associated with reduced vitamin B₁₂ levels, particularly in older adults who often take multiple medications. The drop in vitamin levels was found to depend on the dose and duration of treatment.[2]
Similarly, another research noted that the risk of vitamin B₁₂ deficiency increases with long-term metformin therapy and may be higher when combined with acid-suppressing drugs.[3]
People taking metformin for several years showed a measurable decline in vitamin B₁₂ levels, and those on higher doses were at greater risk.
Vitamin B₁₂ plays a key role in forming red blood cells and maintaining nerve function. Its deficiency can lead to fatigue, numbness, memory problems, or even anaemia. These symptoms often develop gradually, making them easy to miss until the deficiency becomes severe.
Health experts recommend that patients on long-term metformin or acid-suppressing medication get their vitamin B₁₂ levels checked periodically. Monitoring every one to two years can help detect early changes and prevent complications.
Treatment is simple once the deficiency is identified; oral or injectable supplements can restore levels effectively, and most people can safely continue their prescribed medication after discussion with their doctor.[1]
To understand how individuals—particularly those on long-term medications such as metformin or acid-suppressing drugs—can maintain healthy vitamin B₁₂ levels through balanced nutrition, MedBound Times spoke to Sumaiyya Shoaib, Dietitian/Nutritionist (MSc Clinical Nutrition, Isabella Thoburn College, Lucknow), Clinical Dietician at Mr. Johnny Care Services, and Head of Operations – Dietary and Food Services at Green Foods, Lucknow.
Why is vitamin B₁₂ so important for overall health?
Vitamin B₁₂ plays a key role in keeping our nerves healthy, making red blood cells, and supporting DNA production. Without enough, people can feel tired, weak, or develop nerve-related issues.
Can food sources alone correct the deficiency, or are supplements necessary?
For many, especially vegetarians, vegans, or those with absorption problems, relying on food alone may not be enough. Supplements can help restore healthy B₁₂ levels more reliably.
What foods are best for vegetarians or vegans to maintain vitamin B₁₂ levels?
Vegetarians and vegans can turn to fortified foods like plant-based milks, breakfast cereals, and nutritional yeast. B₁₂ supplements are often the most dependable way to meet daily needs.
How can patients on long-term metformin or PPI therapy protect themselves from deficiency?
People taking metformin or proton pump inhibitors (PPIs) long-term should get their B₁₂ levels checked regularly. Supplements can help prevent deficiencies caused by reduced absorption.
What’s your key message for readers on these medications?
If you take these medications for a long time, your body might slowly lose B₁₂ without obvious symptoms. Checking your levels and supplementing when needed can help avoid fatigue, anemia, and nerve problems.
The evidence from both hospital observations and peer-reviewed research highlights a clear message: long-term use of metformin or proton pump inhibitors can lower vitamin B₁₂ levels. The effect may be greater when both medicines are taken together. Regular blood testing and early supplementation can prevent long-term neurological or blood-related complications.
Awareness among both clinicians and patients can ensure that these essential medicines continue to offer their benefits without compromising nutritional health.
References:
The Economic Times. “Apollo Doctor Warns: Two Common Medicines That Affect Vitamin B12 Absorption in the Body.” The Economic Times – Panache, October 2025.
Sarmad Al-Hamdani, M., Alhilo, A., Shaikh, J. et al. Risk of Vitamin B12 Deficiency Associated with Proton Pump Inhibitors, Metformin, and H2 Blockers in Geriatric Patients: A Polypharmacy Perspective. Egypt J Intern Med 37, 127 (2025).
O'Leary F, Samman S. Vitamin B12 in health and disease. Nutrients. 2010 Mar;2(3):299-316. doi: 10.3390/nu2030299. Epub 2010 Mar 5. PMID: 22254022; PMCID: PMC3257642.
(Rh/Eth/SS/MSM)
Edited by M Subha Maheswari
