- Vitamin B12 is a critical component of the diet and can be found in animal food sources.
- Vitamin B12 and its available forms have been the subject of ongoing research.
- A recent comprehensive review discusses key aspects of vitamin B12 and components of natural versus synthetic forms of the vitamin.
Vitamin B12 is important for several things,
Vitamin B12 is available in natural and synthetic forms, and a recent comprehensive review discusses the two, as well as how vitamin B12 relates to different Health conditions, like megaloblastic anemia.
The review was published in Cureus.
The review begins by discussing critical functions of vitamin B12 and what conditions might occur when someone does not get enough vitamin B12. For example, vitamin B12 plays a role in DNA synthesis and cellular metabolism.
Vitamin B12 may also affect symptoms of depression. When someone does not have enough vitamin B12, one condition that may result is megaloblastic anemia, which involves abnormal red blood cells.
Most often, a vitamin B12 deficiency occurs due to problems with absorption or with the body’s use of the vitamin. Vitamin B12 can come from natural sources or be added to food. One particular food that is very high in the vitamin is beef liver.
The recommended daily intake of vitamin B12 is
Some people at higher risk for vitamin B12 deficiency include those with certain digestive tract conditions that affect vitamin B12 absorption, as well as older adults and people following vegetarian or vegan diets.
The cause of deficiency can vary. For example, it can be because of certain conditions like Crohn’s disease, and levels may also be affected by certain medications.
The review further discusses vitamin B12 deficiency and absorption of the vitamin.
Someone with a vitamin B12 deficiency may present with anemia or muscle weakness. Symptoms of vitamin B12 deficiency are vast, but can include weight loss and numbness. It is critical to treat vitamin B12 deficiency, because serious conditions like paralysis could result.
When someone eats food with vitamin B12, it is bound to proteins. It must be removed from these proteins so a specific portion of the small intestine can absorb it. A number of key components are involved in this vitamin B12 absorption, such as pancreatic enzymes.
Next, the review authors discuss their research methods to identify important literature on the topic of vitamin B12. The final comprehensive review included twenty-one articles. The authors’ inclusion timeframe was from 1999 to 2024.
As noted in this review, vitamin B12 is “also known as cyanocobalamin, methylcobalamin, and adenosyl cobalamin.”
According to one cited study, vitamin B12 ultimately becomes a
The evidence suggests that methylcobalamin is a slightly better form of vitamin B12.
For example, animal studies show that cyanocobalamin is excreted at higher levels than methylcobalamin, suggesting better storage of cobalamins when the natural form of methylcobalamin is consumed.
Review author, doctor of osteopathic medicine and Lifestyle Medicine Physician Christopher R. Behringer, explained to Medical News Today that “After review, methylcobalamin may be preferable in many scenarios as methylcobalamin may be more bioavailable and better retained than cyanocobalamin, whether through dietary absorption or supplementation.”
Non-review author Edward Hosbach, DO, FACOFP, a rural family physician for over 35 years, also noted the following about this review to MNT:
“This article is a good reminder of how insidious B12 deficiency can present. Though urgency, route, medical availability and cost can be factors in replacement decisions, the natural active form methylcobalamin could provide some advantages.”
However, this review also notes that natural and synthetic forms of vitamin B12 can both help raise vitamin B12 levels when there are deficiencies.
Evidence further suggests that methylcobalamin may be the best form of supplementation for people who have megaloblastic anemia.
The authors explain that this form skips over several absorption steps so that more is available for the body to use, and that this form can also convert to a molecule called
They emphasize that doctors should first test absorption levels of B12 to decide on the best medication route.
Next, researchers discuss infection and vitamin B12, noting its critical role in red blood cell production and how evidence suggests even red blood cells play a role in the immune response.
Vitamin B12 also affects aspects of immune function, like
The data also supports that vitamin B12 may “help fight viral infections.” When it comes to people with SARS-CoV-2, it is possible that vitamin B12 supplementation could be helpful alongside other COVID-19 treatments to help with certain symptoms, although there is some mixed data.
Still, the review suggests it may be a good idea for doctors to check B12 levels when people have infections.
The authors explain that this work is a literature review and thus mainly relies on information that has already been published. As such, they note it is a challenge to “control for bias across studies or account for population-specific differences.”
Additionally, this review could have missed important information, and there are only three study authors, which could have impacted the outcomes. Any included articles had limitations. For example, some of the research was from non-human studies, which have a limited application to people.
There is a need for greater research in this area.
Behringer noted the following regarding future research needs: “Larger studies need to be done comparing B12 forms, especially in patients with chronic illness, malabsorption, advanced age, or genetic variants affecting metabolism.”
“Long-term clinical outcomes and symptoms need to be prioritized not just serum levels. Key open questions include whether supplementation changes long-term clinical endpoints especially when comparing supplementation delivery and formulation. [Finally,] prophylaxis in high-risk groups may warrant further study,” he added.
The researchers highlight that vitamin B12 plays a critical role in several functions, and certain populations, like older adults, may require supplementation to get enough vitamin B12.
They further highlight methylcobalamin as perhaps the best form of vitamin B12 and encourage screening in groups who are at risk for deficiency. They suggest that finding and addressing deficiencies early could help prevent long-term neuro- and blood-related complications.
Non-review author Aaron Chapa, DC, doctor of chiropractic, alternative clinical nutrition practitioner, and founder of Living Well Clinical Nutrition Center, noted the following:
“This review adds clarity by showing that vitamin B12 works at a cellular and systems level, not just as a simple supplement. It reinforces that B12 supports DNA repair and ongoing cell renewal, helps regulate homocysteine, which affects heart and blood vessel health, plays a role in immune cell activity and immune balance, supports nerve insulation and signaling, influencing memory, mood, and coordination, [and it] is involved in liver function and metabolic pathways.”
People who are concerned about their vitamin B12 levels can discuss it with their doctors. From here, they can see if supplementation or dietary changes may be helpful.
