University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Interaction between vitamin D supplementation and sunlight exposure in women living in opposite latitudes (the D-SOL study).

Mendes, Marcela M (2019) Interaction between vitamin D supplementation and sunlight exposure in women living in opposite latitudes (the D-SOL study). Doctoral thesis, University of Surrey.

[img] Text
MM MENDES E-THESIS 2019 submitted to the University of Surrey.pdf - Version of Record
Restricted to Repository staff only until 28 February 2020.
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (7MB)
[img] Other (Request for embargo)
MM_MENDES_RestrictingAccessThesisForm.docx - N/A or Unknown
Restricted to Repository staff only
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (98kB)

Abstract

Vitamin D deficiency is associated with detrimental effects on bone health and is currently a major global public health issue, with increasing prevalence in both low and high latitude locations. Vitamin D can be synthesised in the skin via sunlight exposure as well as ingested through diet. This study aimed to investigate the interaction and relative contribution of vitamin D supplementation and individual sunlight exposure in raising vitamin D levels above recognized vitamin D cut-off points for deficiency/sufficiency, throughout winter, in ethnically identical adult women living in opposite latitudes. Within two parallel randomized controlled trials (RCT), 135 Brazilian women, (England, n=56, 51˚N; Brazil, n=79, 16˚S), were randomized to receive daily 15 μg vitamin D3 supplements or placebo, for 12 weeks. Oral vitamin D supplementation of 15 μg daily was significantly effective compared to placebo at raising 25(OH)D concentrations over winter, regardless of latitude, and response was dependent on initial 25(OH)D concentrations. Individual UV radiation level was strongly correlated with 25(OH)D concentrations. In both latitudes, supplementation prevented the seasonal concomitant increase in plasma parathyroid hormone (PTH) levels. This research shows: 1) an optimal vitamin D status for bone health around 70-80 nmol/l; 2) the required UV radiation to achieve this status was 1.5 SED; 3) the vitamin D dietary intakes required to achieve these serum levels are 4.5 μg/d at a low and 37 μg/d at higher latitude respectively, with a lower intake of 12 μg/d sufficient to achieve 50 nmol/l in high latitudes. The strength of these results is the novel analysis that directly links human in vivo individual sunlight radiation, increased vitamin D intake and 25(OH)D concentrations, within two parallel RCTs in opposite latitudes. This study demonstrates that a daily supplement of 15 μg vitamin D3 is an effective strategy to significantly raise vitamin D concentrations throughout the winter months in adult females, with important implications for bone health through the concomitant lowering of PTH, regardless of latitude.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
NameEmailORCID
Mendes, Marcela M
Date : 28 February 2019
Funders : Science Without Borders, National Council for Scientific and Technological Development (CNPq, Brazil)
DOI : 10.15126/thesis.00850406
Contributors :
ContributionNameEmailORCID
http://www.loc.gov/loc.terms/relators/THSLanham-New, Susan
http://www.loc.gov/loc.terms/relators/THSHart, Kath
http://www.loc.gov/loc.terms/relators/THSBotelho, Patricia B
Depositing User : Marcela Moraes Mendes
Date Deposited : 07 Mar 2019 12:14
Last Modified : 07 Mar 2019 12:14
URI: http://epubs.surrey.ac.uk/id/eprint/850406

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800