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Vitamin B12: what is methylcobalamin?

yael coopermannopell wong

Reviewed by Yael Cooperman, MD, written by Nopell Wong

Last updated: May 05, 2021
5 min read


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.


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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). 


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Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.