Are You Really Getting Enough B12? Hidden Deficiency Risks Explained
Published 15 days ago • 5 min read
Meeting your Vitamin B12 requirements goes beyond adequate dietary intake.
Even with regular consumption of Vitamin B12-rich foods, deficiencies can still occur. In this article, we explore the causes & risk factors for B12 deficiency, including inadequate dietary intake, malabsorption issues, pernicious anemia, and the impact of medications & treatments.
Understanding these factors can clarify on why Vitamin B12 deficiency can occur, even in individuals who consume animal products.
Causes and Risk Factors for Vitamin B12 Deficiency:
Inadequate Dietary Intake:
Bioavailability of Vitamin B12: The human body has limited ability to synthesize B12, so we rely on dietary sources for an adequate supply. Animal products like meat, fish, eggs, and dairy are rich sources of bioavailable B12, meaning the vitamin is readily absorbed and utilized by our bodies. In contrast, plant-based sources of B12, such as certain algae and fermented foods, often contain inactive analogs of B12, which are not well absorbed. Therefore, vegetarians and vegans who exclude animal products from their diets are at a higher risk of B12 deficiency due to inadequate intake.
Stored Vitamin B12 in the Liver: The liver stores a substantial amount of B12, which acts as a reserve to meet the body’s demands during times of limited intake. However, over time, insufficient dietary intake can deplete these stores, leading to a deficiency. This depletion is a gradual process and can take several years before clinical symptoms manifest.
GI issues & B12 Malabsorption
Malabsorption Issues:
Role of Intrinsic Factor: Intrinsic factor is a protein produced by the stomach that binds to dietary Vitamin B12 and enables its absorption in the small intestine. Conditions like celiac disease, Crohn’s disease, and gastrointestinal surgery can damage the lining of the small intestine or interfere with intrinsic factor production, hindering the absorption of B12. This impaired absorption may result in Vitamin B12 deficiency, even if an individual’s dietary intake is adequate.
Complex Absorption Process: The absorption of Vitamin B12 from food involves several steps and requires the coordinated action of various proteins and receptors in the gastrointestinal tract. Disruption in this process can impair Vitamin B12 absorption. For example, surgical procedures that alter the structure or function of the digestive system can affect the absorption of B12, leading to deficiency.
Testing for Malabsorption: Individuals suspected of having malabsorption issues may undergo specific tests to diagnose the cause. These tests can include measuring Vitamin B12 levels in the blood, assessing intrinsic factor antibodies, or performing an intestinal biopsy. Identifying the underlying condition responsible for malabsorption is needed for appropriate management and treatment.
Pernicious Anemia:
Autoimmune Attack on Intrinsic Factor: Pernicious anemia is an autoimmune condition where the body’s immune system mistakenly attacks and destroys the cells in the stomach that produce intrinsic factor. Without intrinsic factor, the absorption of Vitamin B12 is significantly impaired, leading to deficiency over time. Although the exact cause of pernicious anemia is not fully understood, certain genetic and environmental factors may contribute to its development.
Treatment Options: Individuals with pernicious anemia require lifelong treatment to manage Vitamin B12 deficiency. This typically involves regular injections of B12, bypassing the need for intrinsic factor-mediated absorption. In some cases, high-dose oral supplements of B12 may also be effective. Treating the underlying autoimmune condition may be key to prevent further damage to the stomach & maintain the production of intrinsic factor.
Monitoring and Follow-up: Individuals with pernicious anemia should undergo regular monitoring of their Vitamin B12 levels to ensure they receive adequate supplementation. This includes periodic blood tests to assess Vitamin B12 levels and evaluate the effectiveness of the treatment. Close follow-up with healthcare providers is needed to manage pernicious anemia & preventing complications associated with Vitamin B12 deficiency.
Get B12 tested
Medications and Treatments:
Impact on Gastric Acid Production: Medications such as proton pump inhibitors (PPIs) are commonly used to reduce stomach acid production, treating conditions like gastroesophageal reflux disease (GERD). However, stomach acid is involved in releasing Vitamin B12 from food, making it available for absorption. Prolonged use of PPIs can lower gastric acid levels and subsequently hinder Vitamin B12 absorption, potentially leading to deficiency over time.
Metformin and B12 Absorption: Metformin is a widely prescribed medication for managing type 2 diabetes. Although the exact mechanism is not fully understood, it is believed that metformin can alter the gut microbiome and impair the calcium-dependent membrane action that is necessary for B12 absorption. Regular monitoring of Vitamin B12 levels is recommended for individuals on long-term metformin treatment.
Dialysis and B12 Deficiency: Individuals undergoing long-term dialysis for kidney failure are at an increased risk of Vitamin B12 deficiency due to several factors. Dialysis removes Vitamin B12 from the bloodstream, leading to gradual depletion over time. Additionally, kidney disease often affects the gastrointestinal tract & can impair Vitamin B12 absorption. Regular monitoring and appropriate supplementation are need to manage Vitamin B12 deficiency in individuals on dialysis.
Conclusion:
In summary, meeting your Vitamin B12 needs is more complex than just a balanced diet, as deficiencies can still occur. This article has explored the various causes and risk factors for Vitamin B12 deficiency, including inadequate dietary intake, malabsorption issues, pernicious anemia, and the influence of medications and treatments. Whether it's the challenge faced by vegetarians and vegans, the intricate absorption process within the gastrointestinal tract, or autoimmune conditions like pernicious anemia, the potential for deficiency exists. Regular monitoring, testing, and guidance are needed to manage & prevent the complications associated with Vitamin B12 deficiency in its various forms.
P.S. Check out the other articles in this series on Vitamin B12:
This information is not medical advice. This content and other content on this website is for informational and educational purposes only and is not intended to be a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
References
Ankar A, Kumar A. Vitamin B12 Deficiency. [Updated 2022 Oct 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
Annibale B, Lahner E, Fave GD. Diagnosis and management of pernicious anemia. Curr Gastroenterol Rep. 2011;13(6):518-24.
Bauman WA, Shaw S, Jayatilleke E, Spungen AM, Herbert V. Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin. Diabetes Care. 2000;13(9):1227-31.
Ko SH, Ko SH, Ahn YB, et al. Association of vitamin B12 deficiency and metformin use in patients with type 2 diabetes. J Korean Med Sci. 2014;29(7):965-72.
Lam JR, Schneider JL, Zhao W, Corley DA. Protein pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435-42.
Pawlak R, Lester SE, Babatunde T. The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a review of literature. Eur J Clin Nutr. 2014;68(5):541-8.
Remacha AF, Sarda MP, Canals C, Queralto JM, Zapico E, Remacha J, Carrascosa C. Combined cobalamin and iron deficiency anemia: a diagnostic approach using a model based on age and homocysteine assessment. Ann Hematol. 2013;92(4):527-31.
Swarnakari KM, Bai M, Manoharan MP, Raja R, Jamil A, Csendes D, Gutlapalli SD, Prakash K, Desai DM, Desai A, Khan S. The Effects of Proton Pump Inhibitors in Acid Hypersecretion-Induced Vitamin B12 Deficiency: A Systematic Review. Cureus. 2022 Nov 19;14(11):e3167. doi: 10.7759/cureus.3167.
Miller JW. Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications. Adv Nutr. 2018 Jul;9(4):511S–518S. Published online 2018 Jul 19. doi: 10.1093/advances/nmy023. PMID: 30032223. PMCID: PMC6054240.
Yao, L., Wang, Y., Qin, S. et al. The antidiabetic drug metformin aids bacteria in hijacking vitamin B12 from the environment through RcdA. Commun Biol 6, 96 (2023). https://doi.org/10.1038/s42003-023-04475-0