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
Beef is an excellent source of vitamin B12 (cobalamin).
—
Joy Emeh, Health, 9 Jan. 2026
If you are being treated for a vitamin B12 deficiency, your healthcare provider may monitor your potassium levels.
—Karen Berger, Verywell Health, 6 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
But some studies have found certain nutritional deficiencies, such as vitamin B12 and iron, are associated with early-onset gray hair.
—The Washington Post, San Diego Union-Tribune, 16 Dec. 2025
Some experts also warn about the potential for nutrient deficiencies — particularly vitamin B12, calcium and omega-3 fatty acids.
—Kelly McGreal, FOXNews.com, 17 Nov. 2025
Infused with vitamin B12 to hydrate, nourish, and protect.
—Emily Tannenbaum, Glamour, 10 Nov. 2025
For example, nutrient deficiencies such as not getting enough magnesium, potassium or vitamin B12 can affect nerve and muscle function, making twitches more likely.
—Daryl Austin, USA Today, 8 Nov. 2025
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Joy Emeh, Health, 9 Jan. 2026
If you are being treated for a vitamin B12 deficiency, your healthcare provider may monitor your potassium levels.
—Karen Berger, Verywell Health, 6 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
But some studies have found certain nutritional deficiencies, such as vitamin B12 and iron, are associated with early-onset gray hair.
—The Washington Post, San Diego Union-Tribune, 16 Dec. 2025
Some experts also warn about the potential for nutrient deficiencies — particularly vitamin B12, calcium and omega-3 fatty acids.
—Kelly McGreal, FOXNews.com, 17 Nov. 2025
Infused with vitamin B12 to hydrate, nourish, and protect.
—Emily Tannenbaum, Glamour, 10 Nov. 2025
For example, nutrient deficiencies such as not getting enough magnesium, potassium or vitamin B12 can affect nerve and muscle function, making twitches more likely.
—Daryl Austin, USA Today, 8 Nov. 2025
Cite this Entry
“Vitamin B12.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/vitamin%20B12. Accessed 18 Jan. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
