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May 05, 2021
5 min read

Vitamin B12: what is methylcobalamin?

Methylcobalamin, also called methyl B12, is a type of vitamin B12 crucial to functions in the body. Found naturally in foods, methylcobalamin is available as a supplement for people with a vitamin B12 deficiency.

nopell wong

Written by Nopell Wong

Reviewed by Yael Cooperman, MD

Disclaimer

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

If you think you might be vitamin B12 deficient, don’t worry—there are a lot of supplements out there effective at boosting your levels.

One popular option is methylcobalamin, also known as methyl B12. Let’s look at the benefits of methyl B12 and see how it compares to other forms of this important vitamin.

What is methylcobalamin?

Methylcobalamin is a naturally occurring form of vitamin B12 (also known as cobalamin). This vitamin plays essential roles in your body, including in DNA production, forming red blood cells, and ensuring your nervous system is functioning properly. 

You can get methylcobalamin naturally from foods like fish, meat, eggs, and milk—and it also comes in supplement form. This vitamin is vital for various processes, such as cell growth and protecting nerve fibers. A methyl B12 deficiency can result in symptoms ranging from fatigue to neurological issues (Langan, 2017). 

Are there any advantages to taking methylcobalamin over other forms of vitamin B12?

Along with methylcobalamin, there are three other forms of vitamin B12: adenosylcobalamin, hydroxocobalamin, and cyanocobalamin. Each is effective as a B12 supplement, but there are some differences to note (Obeid, 2015).

Adenosylcobalamin and hydroxocobalamin are naturally occurring forms of B12, which means you can find them in foods. Adenosylcobalamin is less readily available as a supplement compared to methylcobalamin. Hydroxocobalamin is typically offered through injection.

Unlike the rest, cyanocobalamin is the synthetic form of B12 and cannot be found in nature, and is available in both oral and injectable form (Paul, 2017). Research comparing the different kinds of cobalamin supplements is limited. However, all four forms have shown to be effective in helping B12-deficient individuals improve their levels.

How do I know which B12 supplement to take?

All forms of B12 supplements have been shown to improve deficiencies, but does one form reign superior? The answer is hazy, but here’s what we know so far.

Research has found that naturally occurring forms of vitamin B12, such as methylcobalamin and adenosylcobalamin, are preferred over cyanocobalamin. Studies cite these supplements to be safer and have superior bioavailability—meaning a higher chance of being absorbed and utilized by your body (Paul, 2017). 

Some research has shown a combination of active forms of B12 to be especially effective (Thakkar, 2014). In contrast, other studies conclude that methylcobalamin doesn’t provide any additional benefits compared to cyanocobalamin or adenosylcobalamin.

It’s safe to say that there isn’t a consensus about which form of B12 is better—the good news is that all options are likely to help improve a vitamin B12 deficiency (Obeid, 2015).

The National Institutes of Health (NIH) have set a daily recommended allowance of 2.4 micrograms (mcg) of vitamin B12. Because of its low absorption rate, oral B12 supplements often contain 500 to 1000 mcg, or even more (NIH, 2020). 

If you’re thinking about starting a new supplement, it’s always a good idea to consult with a healthcare professional beforehand. Only individuals with B12 deficiency need supplements; most of us get enough B12 from our diets alone.

Roughly 6% of Americans under age of 60 lack B12, while around 20% of those older than 60 have it (Langan, 2017). Below, we discuss in detail who is most at risk for a B12 deficiency. 

How to tell if you need a vitamin B12 supplement

If you think you may have a B12 deficiency, talk to a healthcare provider about any symptoms you’re experiencing. Common symptoms associated with a lack of B12 include fatigue, weakness, loss of appetite, and weight loss. 

B12 is critical for helping your nervous system function properly. If you don’t have enough, you might experience neurological changes including numbness in your hands or feet, balance issues, memory problems, and in extreme cases, dementia (Briani, 2013). 

Some people are also at higher risk of a vitamin B12 deficiency than others. Here are groups most at risk: 

  • People who follow vegetarian or vegan diets: Most B12 that we get comes from animal products. That means that people who limit or eliminate animal products from their diet are at an increased risk of developing B12 deficiency, especially if they don’t take a B12 supplement regularly (Pawlak, 2014). 
  • People with pernicious anemia: Individuals with pernicious anemia (a condition where individuals lack the protein needed to absorb B12) account for the most severe cases of B12 deficiencies. Individuals with this autoimmune disease often require lifelong treatment to maintain healthy B12 levels (Shipton, 2015). 
  • Adults over age 60: In the United States, 6% of adults older than 60 have a B12 deficiency and may benefit from adding a supplement (Shipton, 2015). Between 8-9% of adults 65 years and older have an autoimmune condition called atrophic gastritis, resulting in decreased B12 absorption (Cavalcoli, 2017). 

Alternative sources of B12

Methylcobalamin supplements aren’t the only solution for getting more B12. Here’s a list of the most common ways to get it (NIH, 2020):

  • Diet: If you love eating seafood, you’re in luck. Many of these products contain high levels of B12, including clams, trout, salmon, tuna, and haddock. Beef is another excellent source of B12. Dairy products also contain B12, but in significantly lower amounts than fish and beef. Breakfast cereals fortified with B12 can also provide a portion of your daily recommended intake. 
  • Injections: Vitamin B12 can be administered through intramuscular injections, especially for people with a severe deficiency. Your healthcare provider can decide if you require a B12 shot using a simple blood test to evaluate if your levels are low (Shipton, 2015). 

References

  1. Ahangar, E. R., & Annamaraju, P. (2020). Hydroxocobalamin. In StatPearls. StatPearls Publishing. Retrieved from https://pubmed.ncbi.nlm.nih.gov/32491564/
  2. Briani, C., Dalla Torre, C., Citton, V., Manara, R., Pompanin, S., Binotto, G., & Adami, F. (2013). Cobalamin deficiency: clinical picture and radiological findings. Nutrients, 5(11), 4521–4539. doi: 10.3390/nu5114521. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24248213/
  3. Cavalcoli, F., Zilli, A., Conte, D., & Massironi, S. (2017). Micronutrient deficiencies in patients with chronic atrophic autoimmune gastritis: A review. World Journal of Gastroenterology, 23(4), 563–572. doi: 10.3748/wjg.v23.i4.563. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5292330/
  4. Han, Y., Wang, M., Shen, J., Zhang, Z., Zhao, M., Huang, J., Chen, Y., Chen, Z., Hu, Y., & Wang, Y. (2018). Differential efficacy of methylcobalamin and alpha-lipoic acid treatment on symptoms of diabetic peripheral neuropathy. Minerva Endocrinologica, 43(1), 11–18. doi: 10.23736/S0391-1977.16.02505-0. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27901334/
  5. Gupta, J.K., & Quershi, S.S. (2013). Potential benefits of methylcobalamin: A review. Austin Journal of Pharmacology and Therapeutics, 3(3), 1076. Retrieved from https://austinpublishinggroup.com/pharmacology-therapeutics/fulltext/Ajpt-v3-id1076.php /fulltext/Ajpt-v3-id1076.php
  6. Langan, R. C., & Goodbred, A. J. (2017). Vitamin B12 Deficiency: Recognition and Management. American Family Physician, 96(6), 384–389. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28925645/
  7. National Institutes of Health, Office of Dietary Supplements. (2020). Vitamin B12. Retrieved February 15, 2021 from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/#h5
  8. Obeid, R., Fedosov, S. N., & Nexo, E. (2015). Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Molecular Nutrition and Food Research, 59(7), 1364–1372. doi: 10.1002/mnfr.201500019. Retrieved from https://pubmed.ncbi.nlm.nih.gov/25820384/
  9. Paul, C., & Brady, D. M. (2017). Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms. Integrative Medicine: A Clinician’s Journal, 16(1), 42–49. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312744/
  10. Pawlak, R., Lester, S. & Babatunde, T. The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a review of literature. European Journal of Clinical Nutrition, 68, 541–548 (2014). doi: 10.1038/ejcn.2014.46. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24667752/
  11. Shipton, M. J., & Thachil, J. (2015). Vitamin B12 deficiency – A 21st century perspective. Clinical Medicine, 15(2), 145–150. doi: 10.7861/clinmedicine.15-2-145 Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4953733/
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  13. Thakkar, K., Billa, G. (2015) Treatment of vitamin B12 deficiency–Methylcobalamine? Cyancobalamine? Hydroxocobalamin?—clearing the confusion. European Journal of Clinical Nutrition, 69, 1–2 (2015). doi: 10.1038/ejcn.2014.165. Retrieved from https://pubmed.ncbi.nlm.nih.gov/25117994/
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