Vitamin D: Discovery, Structure, Food Sources

The amount of the vitamin in the multivitamin supplements of vitamin D is typically about:

10-20 ug or 400-800 IU

When was vitamin D discovered?

1922 by E. McCollum

15-30 minute exposure in skin of fair-skinned individuals, wearing a bathing suit, between 10AM to 3PM during the spring, summer, and fall produces about:

250-500 ug vitamin D3

1 ug of vitamin D = _______ IU

40

Over-the-counter supplements providing solely vitamin D often contain up to:

50 ug or 2,000 IU

RDA for vitamin D in IU:

600 IU

__-________________ is synthesized in the sebaceous glands

7-dehydrocholesterol

Older adults may produce up to ___% less vitamin D3 in the skin due to:

75%; diminished 7-dehydrocholesterol content in the skin

Most vitamin D supplements provide ___ although some still contain _______.

D3; D2

Supplementation with the ______ form is more potent than ______.

D3; D2

The vitamin D content of foods is expressed as

International units - IU or ug

Vitamin D3 is synthesized by the skin in response to:

UV radiation from sunlight

Unstable double bonds in Previtamin D₃ are rearranged to produce:

Vitamin D₃ (cholecalciferol)

Vitamin D is derived from

a steroid

7-dehydrocholesterol's conjugated set of double bonds allows for:

absorption of specific wavelengths in the UV range

Key food sources of vitamin D:

animal products

Vitamin D3 - cholecalciferol is found in:

animal-based foods such: fatty fish, egg yolks, and liver fortified foods such as: cereal, milk, and orange juice

Synthesized from the sun, vitamin D3, then diffuses from the skin into the

blood

7-dehydrocholesterol is secreted onto the skin's surface and uniformly:

distributed throughout the epidermis and dermis

7-dehydrocholesterol has a conjugated set of __________ ________.

double bonds

Rickets was found to be prevented by:

fat-soluble factor D in the diet or by body exposure to UV light

The largest quantities of vitamin D3 are found in

fatty fish (because they synthesize UV radiation same as humans)

Very few foods contain vitamin D, so some foods are _________ with vitamin D3 in the U.S.

fortified

Previtamin D₃ (precalciferol) is made:

in the skin of humans with exposure to UBV photons from sunlight

Vitamin D contains three:

intact rings - A,C,D

Only ___________ plant products are good sources of vitamin D

irradiated (e.g. mushrooms)

Those with darker skin color need longer sun exposure time to generate vitamin D because:

melanin blocks some of the UVB rays

Does the sun have vitamin D?

no

What happens to vitamin D with cooking?

nothing, stable in foods (not prone to cooking, storage, or processing losses)

During exposure to sunlight, 7-dehydrocholesterol absorbs

photons

Vitamin D2 - ergocalciferol is obtained from

plants and fungi when exposed to UV radiation

B rings opens, structure becomes:

pre-calciferol (previtamin D₃)

Childhood disease characterized by improper bone development

rickets

Vitamin D is considered a:

seco-steroid

Time it takes to produce vitamin D3 from sun:

several hours to a few days

One of Vitamin D's four rings is broken in:

the B ring between carbons 9 and 10

What is the main source of vitamin D?

the sun

In the blood, vitamin D3 is transported bound to

vitamin D binding protein - VDBP

Two main forms of vitamin D:

vitamin D2 - ergocalciferol and vitamin D3 - cholecalciferol