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
Certain drinks may provide health benefits—like beet juice for blood pressure or milk for vitamin B12.
—
Jenna Anderson, Health, 13 Mar. 2026
That said, there’s no scientific evidence that taking a vitamin B12 supplement, or even eating more foods with vitamin B12, can stop hair loss from happening.
—Rebecca Strong, USA Today, 16 Feb. 2026
Each drink has 2 billion probiotics and vitamin B12 for energy.
—Bestreviews, Chicago Tribune, 16 Feb. 2026
Mayo Clinic says metformin is generally safe, but can cause digestive side effects and vitamin B12 deficiency in some patients.
—Khloe Quill, FOXNews.com, 10 Feb. 2026
Both magnesium and vitamin B12 supplements are most helpful when used to correct deficiencies and under the guidance of a healthcare provider.
—Kristen Gasnick, Verywell Health, 27 Jan. 2026
Sure, red meat can be quite rich in protein as well as other important nutrients like iron, zinc, potassium, vitamin B6 and vitamin B12.
—Bruce Y. Lee, Forbes.com, 19 Jan. 2026
Some insist the drug must be paired with vitamin B12, omega-3, or a certain amino acid; others caution that dairy can reduce its effectiveness.
—Tom Bartlett, The Atlantic, 19 Dec. 2025
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Jenna Anderson, Health, 13 Mar. 2026
That said, there’s no scientific evidence that taking a vitamin B12 supplement, or even eating more foods with vitamin B12, can stop hair loss from happening.
—Rebecca Strong, USA Today, 16 Feb. 2026
Each drink has 2 billion probiotics and vitamin B12 for energy.
—Bestreviews, Chicago Tribune, 16 Feb. 2026
Mayo Clinic says metformin is generally safe, but can cause digestive side effects and vitamin B12 deficiency in some patients.
—Khloe Quill, FOXNews.com, 10 Feb. 2026
Both magnesium and vitamin B12 supplements are most helpful when used to correct deficiencies and under the guidance of a healthcare provider.
—Kristen Gasnick, Verywell Health, 27 Jan. 2026
Sure, red meat can be quite rich in protein as well as other important nutrients like iron, zinc, potassium, vitamin B6 and vitamin B12.
—Bruce Y. Lee, Forbes.com, 19 Jan. 2026
Some insist the drug must be paired with vitamin B12, omega-3, or a certain amino acid; others caution that dairy can reduce its effectiveness.
—Tom Bartlett, The Atlantic, 19 Dec. 2025
Cite this Entry
“Vitamin B12.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/vitamin%20B12. Accessed 21 Mar. 2026.
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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