vitamin D

noun

: any or all of several fat-soluble vitamins chemically related to steroids, essential for normal bone and tooth structure, and found especially in fish-liver oils, egg yolk, and milk or produced by activation (as by ultraviolet irradiation) of sterols: such as

a

or vitamin D₂

-ˈdē-ˈtü 

: calciferol

b

or vitamin D₃

-ˈdē-ˈthrē 

: cholecalciferol

Examples of vitamin D in a Sentence

Recent Examples on the Web

More than half of people with type 2 diabetes in the Americas may be deficient in essential nutrients like vitamin D, magnesium, and vitamin B12, a new study found. —Kaitlin Sullivan, Health, 6 Feb. 2025

Silva explains that magnesium activates vitamin D, which, in turn, regulates the parathyroid hormone—the key hormone that controls calcium levels in the body. —Jennifer Shanker, Flow Space, 6 Feb. 2025

In children, severe vitamin D deficiency can lead to rickets, a condition that weakens bones.9 Vitamin D requirements vary by age and range from 400 to 800 IU. —Melissa Nieves, Verywell Health, 30 Jan. 2025

Some studies point to the roles of female hormones, a lack of vitamin D, inflammation and even obesity as potential factors. —Cindy Krischer Goodman, Sun Sentinel, 28 Jan. 2025

Word History

First Known Use

circa 1921, in the meaning defined above

Kids Definition

vitamin D

noun

: any of several vitamins that are needed for normal bone and tooth structure, and are found especially in fish-liver oils, egg yolk, and milk or are produced in response to ultraviolet light

Medical Definition

vitamin D

noun

: any or all of several fat-soluble vitamins chemically related to steroids, essential for normal bone and tooth structure, and found especially in fish-liver oils, egg yolk, and milk or produced by activation (as by ultraviolet irradiation) of sterols: as

a

: calciferol

b

: cholecalciferol

called also sunshine vitamin