Talk:Vitamin D

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Do μg and IU refer to D3?

Vitamin D is a group of secosteroids. Amounts in IU and μg and given throughout the article, but I only see one case that states which form it refers to (D3). At a guess they're all D3 but this should be explicit. According to this https://walrus.com/questions/converting-micrograms-mcg-of-calcitriol-to-international-units one IU of D3 is equivalent to one IU of D2, but it makes no sense to talk about an IU of calcitriol as no amount of it can be said to be equivalent to one IU of D3. The URL above does not look like a citable reference, despite looking very scholarly, so I won't edit the article, but someone more knowledgeable might want to, to say something like "all references to IU are to D3" and something similar for μg if that's true. Housecarl (talk) 00:31, 9 December 2023 (UTC)[reply]

Housecarl - New talk topics go to the bottom of the page, WP:TALK. This section of the article explains thoroughly the relationship between μg and IU for D3 and D2 food or supplement sources, which do not distinguish a possible difference in vitamin D production between the two substrates. Calcitriol is not expressed in the article in units of μg or IU. Zefr (talk) 17:28, 9 December 2023 (UTC)[reply]
My point was "Vitamin D" is a group of things and the quantities given do not identity which of those things they refer to. But now I see the Types section says "Vitamin D without a subscript refers to either D2 or D3, or both, and is known collectively as calciferol.[citation needed]". Housecarl (talk) 21:36, 9 December 2023 (UTC)[reply]

Production from sunlight

I What to add this two sections Production from sunlight and Absorption in the body from the sun. I have tried after best ability to follow WP:MEDRS.

To convey the difficulties, with getting vitamin D from the sun. And that getting vitamin D from sun/previtamin D is a different from supplement.


Production from sunlight

Finse: 60°N and 1220 m AMSL
Oslo, Bergen 60°N and 0 m AMSL,
Tromsø 69°N and 0 m AMSL,
Ny-Ålesund 78°N and 0 m AMSL.
Maximum UV index and how it varies throughout the year in Norway.

To produce Vitamin D, UVB light is required. To have sufficient light containing UVB, the UV index needs to be 3 or higher (≥45 solar zenith angle at sea level).[1] Vitamin D production is maximal at one-third of the minimal erythemal dose. When UV exposure increases to a minimal erythemal dose, vitamin D synthesis stops.[2] One must be south of latitude 50°N to produce vitamin D around the Winter solstice.[3]

Number of minutes at different UV levels to achieve sufficient monthly needs[4][5]
SKIN REACTION TO SUNLIGHT UV INDEX
0-2 3-5 6-7 8-10 11+
Skin type I:

Always burn, never tan

56-∞ 10-15 5-10 2-8 1-5
Skin type II:

Burn easily, rarely tan

80-∞ 15-20 10-15 5-10 2-8
Skin type III:

Occasionally burn, slowly tan

90-∞ 20-30 15-20 10-15 5-10
Skin type IV:

Rarely burn, rapidly tan

140-∞ 30-40 20-30 15-20 10-15
Skin type V & VI:

Very rarely burn, always dark

180-∞ 40-60 30-40 20-30 15-20

The table assumes that one is outdoors in sunlight for more than 3 times a week, wearing only swim trunks and a t-shirt or swimsuit, and has not applied sunscreen. Such exposure to the entire skin surface corresponds to receiving between 250–1250 μg of vitamin D (10k to 50k IU) per session[6], or a similar amount as obtained by consuming 125–500 ml of cod liver oil (200μg/100ml[7]).

The "summer level" decreases to "winter level" within 6 to 8 weeks after insufficient sun exposure, without supplementation.[8]

Barriers to UVB absorption:

  • Sunscreen
  • Clothing covering a larger area
  • Overcast skies
  • Staying in the shade
  • Insufficient UV index.

Absorption in the body from the sun

Vitamin D absorption from sunlight differs from absorption from supplements.[9] When absorbing 3 minimum erythema doses (the time it takes for the skin to turn red), with the whole body exposed to UV light:

  • Within 24 hours, serum vitamin D levels rose from 15 nmol/l to 149 nmol/l.
  • After 1 week, serum vitamin D fell back to its initial value, while serum 1,25-(OH)2-D reached its peak.
  • Between 2-3 weeks, serum 25-OH-D concentration reached its highest level, while serum 1,25-(OH)2-D fell back to its initial value.

The study does not mention the time it takes for serum 25-OH-D to return to its initial value.

In another study comparing the difference between 1 MED, 625μg D2 (25k IU) supplement, and 250μg D2 (10k IU) supplement[10][11][12][13], they found that vitamin D from the sun lasts significantly longer than supplements. Vitamin D from supplements returned to baseline levels within 2 days, whereas vitamin D from the sun returned after 7 days. EidenNor (talk) 08:02, 24 April 2024 (UTC)[reply]

  1. ^ Kallioğlu, Mehmet Ali; Sharma, Ashutosh; Kallioğlu, Ayşan; Kumar, Sunil; Khargotra, Rohit; Singh, Tej (2024-02-12). "UV index-based model for predicting synthesis of (pre-)vitamin D3 in the mediterranean basin". Scientific Reports. 14 (1): 3541. doi:10.1038/s41598-024-54188-5. ISSN 2045-2322. PMID 38347060.
  2. ^ "Benefits and Risks of Sun Exposure to Maintain Adequate Vitamin D Levels". PubMed Central. 2023-05-05. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
  3. ^ "Vitamin D and UV". Science Learning Hub. Retrieved 2024-04-05.
  4. ^ "Get Vitamin D from Sun Exposure". www.gbhealthwatch.com. Retrieved 2024-04-23.
  5. ^ "Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status and no sunburn". fastrt.nilu.no. Retrieved 2024-04-23.
  6. ^ "Benefits of Sunlight: A Bright Spot for Human Health". PubMed Center. March 2008. Retrieved 2024-03-24. {{cite web}}: Cite uses deprecated parameter |authors= (help)
  7. ^ stok (2017-10-11). "Tran og Vitamin D - Kilder og tilskudd - Möller's". Møllers (in Norwegian Bokmål). Retrieved 2024-03-09.
  8. ^ Cicarma, Emanuela; Porojnicu, Alina Carmen; Lagunova, Zoya; Dahlback, Arne; Juzeniene, Asta; Moan, Johan (2009-09-01). "Sun and sun beds: inducers of vitamin D and skin cancer". Anticancer Research. 29 (9): 3495–3500. ISSN 1791-7530. PMID 19667143.
  9. ^ Holick, M. F. (1981-07-01). "The cutaneous photosynthesis of previtamin D3: a unique photoendocrine system". The Journal of Investigative Dermatology. 1. 77: 51–58. doi:10.1111/1523-1747.ep12479237. ISSN 0022-202X. PMID 6265564. Retrieved 2024-04-05.
  10. ^ Haddad, J. G.; Matsuoka, L. Y.; Hollis, B. W.; Hu, Y. Z.; Wortsman, J. (1993-06-01). "Human plasma transport of vitamin D after its endogenous synthesis". The Journal of Clinical Investigation. 6. 91: 2552–2555. doi:10.1172/JCI116492. ISSN 0021-9738. PMID 8390483. Retrieved 2024-04-05.
  11. ^ Holick, Michael F (2004-03-01). "Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis12345". The American Journal of Clinical Nutrition. 3. 79: 362–371. doi:10.1093/ajcn/79.3.362. ISSN 0002-9165. Retrieved 2024-04-05.
  12. ^ Holick, Michael F. (2009-03-01). "Vitamin D and Health: Evolution, Biologic Functions, and Recommended Dietary Intakes for Vitamin D". Clinical Reviews in Bone and Mineral Metabolism. 1. 7: 2–19. doi:10.1007/s12018-009-9026-x. ISSN 1559-0119. Retrieved 2024-04-05.
  13. ^ {{cite journal |access-date=2024-04-05 |date=2011-08-01 |doi=10.2310/JIM.0b013e318214ea2d |first=Michael F. |issn=1708-8267 |last=Holick |pages=872–880 |periodical=Journal of Investigative Medicine: The Official Publication of the American Federation for Clinical Research |pmc=3738435 |pmid=21415774 |series=6 |title=Vitamin D: a d-lightful solution for health |url=https://pubmed.ncbi.nlm.nih.gov/21415774/ |volume=59}
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