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25 minutes of daily sun provided less than half of the response as 500 IU of vitamin D (Korea) – RCT March 2019

Effect of sun exposure versus oral vitamin D supplementation on serum 25-hydroxyvitamin D concentrations in young adults: A randomized clinical trial

Hee-Kyung Joha,b,c, Hee-Kyung Joh Hee-Kyung Joh, Hwang Seung-sikd, Be Long Chob,e,f,g, Chun Soo Limh, Sung-Eun Jungi
DOI: https://doi.org/10.1016/j.clnu.2019.03.021


No – 10 minutes per day of sun-UVB is NOT enough contains the following summary

  • 5-10 minutes provides only 1,000 IU ONLY IF you are near the equator
  • AND young
  •  AND not obese
  •   AND have light skin
  •    AND it is summer
  •     AND it is the middle of the day
  •      AND you have lots of skin exposed to the sun
  •       AND you are lying down
  •        AND you are not wearing sunscreen
  •         AND you have a healthy Liver
  •          AND no clouds and nor air pollution
  •           AND you have good response to sunshine (4X variation between individuals)

Note: The abstract does not indicate

  1. amount of clothing worn
  2. the season of the year - hopeuflly summer
  3. standing vs lying down - can be a 4X differ4ence
  4. Age of adult - can be a 4X difference
  5. % of the days were cloudy ( ~3X reducion on cloudy days)
  6. % of compliance "compliance relatively low"

 Download the PDF from Sci-Hub via VitaminDWiki

Sun was only slightly better than placebo


Vitamin D inadequacy is associated with a wide range of diseases. However, optimal strategies to improve vitamin D status, especially in Asian populations, remain unclear. We tested the hypotheses that (1) relevant sun exposure or oral vitamin D supplementation would significantly increase serum 25-hydroxyvitamin D (25OHD) concentrations compared with placebo, (2) sun exposure and supplementary vitamin D would be similar in serum 25OHD increases, and (3) the two interventions may have different effects on cardio-metabolic markers.

In this 8-week randomized placebo-controlled clinical trial including vitamin D-deficient adults in Seoul (37 °N), Korea, changes in serum 25OHD concentrations were compared between the sun exposure (daily ≥ 20–30 minutes around noon, n = 50), oral vitamin D3 (500 IU/d, n = 50), and control (placebo, n = 50) groups.

Both sun exposure and oral vitamin D3 effectively increased serum 25OHD concentrations. Compared with placebo, the between-group least-squares mean (LSM) differences in changes were 2.2 ng/mL (95% CI: 0.2, 4.2) in the sun exposure group and 8.5 ng/mL (6.5, 10.5) in the oral vitamin D3 group. Increases in serum 25OHD were greater with oral vitamin D3 than with sun exposure (LSM difference in changes = 6.3 ng/mL, 95% CI: 4.3, 8.3). More participants in the oral vitamin D3 group (54.2%) achieved serum 25OHD concentrations ≥ 20 ng/mL at week 8 than those in the sun exposure (12.2%) or control (4.3%) groups. Compliance with sun exposure advice was relatively low, and only those with adequate compliance had a significant increase in serum 25OHD. Changes in the cardio-metabolic markers were mostly insignificant in all groups.

Enhanced sun exposure and 500 IU/d of oral vitamin D3 supplementation significantly increased serum 25OHD concentrations. However, our protocol for sun exposure was not as effective as 500 IU/d of oral vitamin D3 supplementation.

This trial was registered at clinicaltrials.gov as NCT03310242.

Created by admin. Last Modification: Monday April 1, 2019 21:12:28 GMT-0000 by admin. (Version 8)

Attached files

ID Name Comment Uploaded Size Downloads
11701 UV vs sun 25 minute.pdf PDF 2019 admin 01 Apr, 2019 21:11 660.47 Kb 495
11668 25 min vs 500 IU.jpg admin 26 Mar, 2019 16:12 11.84 Kb 395
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