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Half-life of vitamin D varies

Vitamin D Half-Life is '1-6 weeks''

Half-life: the time till half of the quantity still exists
Example: Start with 30 ng of vitamin D and half-life of 6 weeks, then 15 ng at 6 weeks

Half-life varies with:

  • Vitamin D level
  • Vitamin D Source: guesses for 20 ng (shorter half-life for >50 ng)
    6 weeks: Sun/UV
    3 weeks: D3 supplements
    1 week: D2 supplements
  • 1-2 day: Trauma/surgery

Half-life might also vary with such things as:

Wikipedia - Biological half-life

Clinical practice: 4 to 5 X the half-life to reach steady state
   Example: 4X 2-6 week ==> 2-6 month to reach steady state

It appears that

@ 10 nanograms: half-life (sun) = about 12 weeks
@ 50 nanograms: half-life (sun) = about 2 week

8+ VitaminDWiki pages have HALF-LIFE in the title

This list is automatically updated

Items found: 8

See also VitaminDWiki

see wikipage: http://www.vitamindwiki.com/tiki-index.php?page_id=2475

Notion of Vitamin D benefit vs dosing frequency for > 50 nanograms
see wikipage http://www.vitamindwiki.com/tiki-index.php?page_id=2475

Example at 27 nanograms, half-life is about 7 weeks
see wikipage http://www.vitamindwiki.com/tiki-index.php?page_id=1046

Example of half life while adding 10,000 IU of vitamin D3
Nutrition: US recommendations fail to correct vitamin D deficiency
From Heaney 2003

Example of half life vitamin D2
D2 10000 and 25000 - Holick 2004

Example of vitamin D from the sun 1 week to double
same reference has an adjustment function to account for the photodegradation of vitamin D by the sun

25 day half-life of 16 ng vitamin D (used stable-isotope labeled molecules) – June 2014

25(OH)D2 half-life is shorter than 25(OH)D3 half-life and is influenced by DBP concentration and genotype.
J Clin Endocrinol Metab. 2014 Jun 2:jc20141714
Jones KS1, Assar S, Harnpanich D, Bouillon R, Lambrechts D, Prentice A, Schoenmakers I.
Medical Research Council (MRC) Human Nutrition Research, Cambridge, UK.

Context: There is uncertainty over the equivalence of vitamins D2 and D3 to maintain plasma 25-hydroxyvitamin D (25(OH)D).

Objective: To compare the plasma half-lives of 25(OH)D2 and 25(OH)D3 in two distinct populations with different dietary calcium intake and 25(OH)D status.

Participants: Healthy men (aged 24 and 39 years), resident in The Gambia (n=18) or UK (n=18). Interventions: Oral tracer dose of deuterated-25(OH)D2 and deuterated-25(OH)D3 (both 40 nmol). Blood samples were collected over 33 days.

Main outcome measures: 25(OH)D2 and 25(OH)D3 plasma half-lives, concentrations of 25(OH)D and DBP and DBP genotypes.

Results: 25(OH)D2 half-life (mean (SD)) (13.9 (2.6) d) was shorter than 25(OH)D3 half-life (15.1 (3.1) d; P=0.001) for countries combined, and in Gambians (12.8 (2.3) d vs. 14.7 (3.5) d; P<0.001), but not in the UK (15.1 (2.4) d vs. 15.6 (2.5) d; P=0.3).
25(OH)D concentration was 69 (13) and 29 (11) nmol/L (P<0.0001) and DBP concentration was 259 (33) and 269 (23) mg/l (P=0.4) in The Gambia and UK, respectively.

Half-lives were positively associated with plasma DBP concentration for countries combined: (25(OH)D2 half-life: regression coefficient (SE) 0.03 (0.01) d per 1 mg/l DBP; P=0.03; 25(OH)D3 half-life: 0.04 (0.02) d; P=0.02) and in Gambians (25(OH)D2 half-life: 0.04 (0.01) d; P=0.02; 25(OH)D3 half-life: 0.06 (0.02) d; P=0.01), but not in UK participants.
DBP concentration*country interactions were not significant. DBP Gc1f/1f homozygotes had shorter 25(OH)D2 half-lives compared to other combined genotypes (P=0.007), after correction for country.

Conclusions: 25(OH)D2 half-life was shorter than 25(OH)D3 half-life, and half-lives were affected by DBP concentration and genotype. Stable isotope 25(OH)D half-life measurements provide a novel tool to investigate vitamin D metabolism and vitamin D expenditure, and aid in the assessment of vitamin D requirements.

Comment by VitaminDWiki
There is no indication in the abstract as to the pre-existing vitamin D blood levels.
They apparently added 16 ug (640 IU) stable isotope labelled molecules D2 and D3

See also VitaminDWiki - UVB with/without UVA

short url = http://is.gd/halflifeD