Vitamin D status in a Norwegian population: any link to lung function?
Doctoral thesis
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http://hdl.handle.net/11250/284534Utgivelsesdato
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Sammendrag
Vitamin D is predominantly synthesized from precursors in the skin after direct
exposure to ultraviolet B radiation from the sun. Vitamin D can also be obtained by
dietary intake of vitamin D rich food, or by supplement intake. Poor vitamin D status
has been reported worldwide. Determinants include unexposed skin, high latitude,
winter season, and high body mass index (BMI). Serum 25-hydroxyvitamin D
(25(OH)D) is the major circulating metabolite of vitamin D and considered the best
marker of vitamin D status. The association between vitamin D status and bone health is
well studied, and increasing evidence suggests an association between low serum
25(OH)D level and range of non-skeletal health outcomes including respiratory
disorders, such as asthma.
This dissertation uses data from the Nord-Trøndelag Health Study (HUNT), one
of the largest population based health studies in Norway, with clinical, lifestyle and
environmental information on more than 130,000 people collected over 25 years. Using
data from HUNT2 (1995-1997) and HUNT3 (2006-2008), we investigated: 1) the
prevalence of vitamin D deficiency (serum 25(OH)D<50nmol/L) in a general adult
population and factors associated with vitamin D deficiency; 2) the association between
serum 25(OH)D level and lung function (LF) in adults with asthma; and 3) the
interrelationship between serum 25(OH)D level, smoking and LF changes in a general
adult population.
We found a high prevalence of vitamin D deficiency in this Norwegian
population (40% overall), particularly in winter months (64%). Besides season and high
BMI, several potentially modifiable lifestyle factors were associated with vitamin D deficiency. We also found that low serum 25(OH)D level was not associated with
airway obstruction in most adults with asthma, with the exception of men with asthma
but without allergy status. Finally, we found no clear associations between serum
25(OH)D levels and LF changes in never smokers, whereas we did observe significant
associations in ever smokers.
Replication and confirmation of these findings via well-designed prospective
and intervention studies is required to determine if vitamin D supplementation is a
potentially cost effective, safe and straightforward means of asthma control or disease
mitigation in ever smokers.
Består av
Paper 1: Larose, Tricia L; Chen, Yue; Camargo, Carlos Arthuro; Langhammer, Arnulf; Romundstad, Pål Richard; Mai, Xiao-Mei. Factors associated with vitamin D deficiency in a Norwegian population: the HUNT Study. Journal of Epidemiology and Community Health 2014 ;Volum 68.(2) s. 165-170 Is not included due to copyright. Available at http://dx.doi.org/10.1136/jech-2013-202587Paper 2: Larose, Tricia L; Langhammer, Arnulf; Chen, Yue; Camargo, Carlos A; Romundstad, Pål Richard; Mai, Xiao-Mei. Serum 25-hydroxyvitamin D levels and lung function in adults with asthma: the HUNT Study. European Respiratory Journal 2015 ;Volum 45.(4) s. 1019-1026 Is not included due to copyright. Available at http://dx.doi.org/10.1183/09031936.00069714
Paper 3: Larose, Tricia L; Brumpton, Ben Michael; Langhammer, Arnulf; Camargo, Carlos A; Chen, Yue; Romundstad, Pål Richard; Mai, Xiao-Mei. Serum 25-hydroxyvitamin D level, smoking and lung function in adults: the HUNT Study. European Respiratory Journal 2015 Is not included due to copyright. Available at http://dx.doi.org/10.1183/09031936.00226614