vitamin B12
noun
1
: a complex cobalt-containing compound C63H88CoN14O14P that occurs especially in liver, is essential to normal blood formation, neural function, and growth, and is used especially in treating pernicious and related anemias and in animal feed as a growth factor
called also cyanocobalamin
2
: any of several compounds similar to vitamin B12 in action but having different chemistry
Examples of vitamin B12 in a Sentence
Recent Examples on the Web
Advertisement You can get tested for a vitamin B12 deficiency at your annual physical.
—
Perri Ormont Blumberg, Time, 13 Aug. 2025
Algae oil contains low levels of saturated fat and high levels of omega-9 fatty acids, as well as other nutrients like vitamin B12 and magnesium.
—Sarah Bence, Verywell Health, 6 Aug. 2025
Most fat-soluble vitamins, including vitamins A and E, as well as water-soluble vitamins like vitamin C and vitamin B12, are not significantly impacted.
—Jillian Kubala, Health, 31 July 2025
Adding easily available ingredients, such as vitamin B12, wouldn’t make compounded versions of weight-loss drugs legal now that the shortage is over, according to GoodRx.
—Meg Wingerter, Denver Post, 15 July 2025
Tuna is also nutritious, providing omega-3 fats and nutrients like vitamin B12, vitamin D, iron, and selenium, which are often lacking in many people’s diets.26
However, raw and canned tuna contains the heavy metal mercury.
—Jillian Kubala, Health, 8 July 2025
Most supplements provide much more vitamin B12—as much as 1,000 micrograms.
—Kirstyn Hill, Health, 15 July 2025
Cow's milk is naturally rich in protein, calcium, and essential vitamins, including vitamin B12.
—Lana Barhum, Verywell Health, 12 July 2025
Low thyroid or vitamin deficiencies (vitamin D or vitamin B12) can cause fatigue, mood changes and low libido.
—Dr. Jamin Brahmbhatt, CNN Money, 8 July 2025
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Perri Ormont Blumberg, Time, 13 Aug. 2025
Algae oil contains low levels of saturated fat and high levels of omega-9 fatty acids, as well as other nutrients like vitamin B12 and magnesium.
—Sarah Bence, Verywell Health, 6 Aug. 2025
Most fat-soluble vitamins, including vitamins A and E, as well as water-soluble vitamins like vitamin C and vitamin B12, are not significantly impacted.
—Jillian Kubala, Health, 31 July 2025
Adding easily available ingredients, such as vitamin B12, wouldn’t make compounded versions of weight-loss drugs legal now that the shortage is over, according to GoodRx.
—Meg Wingerter, Denver Post, 15 July 2025
Tuna is also nutritious, providing omega-3 fats and nutrients like vitamin B12, vitamin D, iron, and selenium, which are often lacking in many people’s diets.26
However, raw and canned tuna contains the heavy metal mercury.
—Jillian Kubala, Health, 8 July 2025
Most supplements provide much more vitamin B12—as much as 1,000 micrograms.
—Kirstyn Hill, Health, 15 July 2025
Cow's milk is naturally rich in protein, calcium, and essential vitamins, including vitamin B12.
—Lana Barhum, Verywell Health, 12 July 2025
Low thyroid or vitamin deficiencies (vitamin D or vitamin B12) can cause fatigue, mood changes and low libido.
—Dr. Jamin Brahmbhatt, CNN Money, 8 July 2025
Cite this Entry
“Vitamin B12.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/vitamin%20B12. Accessed 22 Aug. 2025.
Copy CitationMedical Definition
vitamin B12
noun1
: a complex cobalt-containing compound C63H88CoN14O14P found in animal products (as meat and eggs) that is essential to normal blood formation, neural function, and growth and is used especially in treating pernicious and related anemias and in animal feed as a growth factor
called also cyanocobalamin
2
: any of several compounds similar to vitamin B12 in action but having different chemistry
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