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
- 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
- Sickness - especially inflammation 2 days?
- Amount of Calcium in bloodstream
- Type of food
- Ratio of UVB to UVA - Excess UVA appears to decrease Vitamin D
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
@ 10 nanograms: half-life (sun) = about 12 weeks
@ 50 nanograms: half-life (sun) = about 2 week
- All "Half-life" but not 'vitamin K" in VitaminDWiki 633 items as of July 2017
- Vitamin D half-life was 20 days (pregnant in Gambia) – May 2016
- Fat soluable vitamins decrease quickly after trauma Decrease by 59% in a single day
- Loading dose results in an increase in vitamin D far faster than a constant dose
- Vitamin D levels of critically ill patients reduced 35 % after blood dilution – Nov 2010
- Vitamin D3 half-life about 10 days with pancreatitis inflammation – 2011
- Overview Vitamin D3 not D2
- Vitamin D2 half-life about 3 days – April 2012
- 70,000 IU of vitamin D had about 30 day half-life – Dec 2012
- Take vitamin D3 daily or weekly which has the following graphics
Notional of Vitamin D benefit vs dosing frequency of < 30 nanograms
Notion of Vitamin D benefit vs dosing frequency for > 50 nanograms
Example at 27 nanograms, half-life is about 7 weeks
Example of half life while adding 10,000 IU of vitamin D3
Example of half life vitamin D2
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. [Epub ahead of print]
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
- UVB lamp produced 8X as much vitamin D as same intensity from the sun – July 2012
Did the UVB bulb have very little or no UVA?
- UVA from some tanning beds and most windows decrease vitamin D blood levels – March 2012
- Study of Vitamin D3 from UV lamps – Aug 2010.pdf file
- UVA through window glass decreases vitamin D
- Mirror made with special plexiglass should reflect all light except UVB
short url = http://is.gd/halflifeD