Thesis for the degree of Master of Science in Human Nutrition Faculty of Food Science and Nutrition, School of Health Sciences University of Iceland 2014

Autumn vitamin D intake and status in 7-year-old school children - Vitamin D status vs. week in autumn, intake of vitamin D containing foods, and cardiorespiratory fitness - And comparison of the diet of 7-year-olds in 2006 and the diet of 6year-olds in 2011 –

Adda Bjarnadóttir

Supervisors: Professor Inga Þórsdóttir and Dr. Ása Guðrún Kristjánsdóttir

D-vítamínbúskapur og D-vítamínneysla meðal 7 ára íslenskra skólabarna á haustmánuðum - Tengsl D-vítamínbúskapar við vikunúmer að hausti, inntöku á matvælum sem innihalda D-vítamín og þol - Samanburður á mataræði 7 ára barna 2006 og 6 ára barna 2011 -

Adda Bjarnadóttir

Lokaverkefni til MS-gráðu í næringarfræði Leiðbeinendur: Inga Þórsdóttir prófessor og Dr. Ása Guðrún Kristjánsdóttir Matvæla- og næringarfræðideild Heilbrigðisvísindasvið Háskóla Íslands Febrúar 2014

                                     

Ritgerð þessi er til meistaragráðu í næringarfræði og óheimilt er að afrita ritgerðina á nokkurn hátt nema með leyfi rétthafa. Adda Bjarnadóttir 2014 Prentun: Reykjavík, Ísland 2014

I. Ágrip ......................................................................................................................... ii   II. Abstract.................................................................................................................. iii   III. Acknowledgements...............................................................................................iv   IV. Abbreviations.........................................................................................................v   Introduction..................................................................................................................1   Review of the literature ...............................................................................................3   Vitamin D intake and status.......................................................................................................3   Iceland........................................................................................................................................................... 3   Europe and worldwide............................................................................................................................. 4   History of fish liver oil intake............................................................................................................... 4   Cut-off levels of s-25(OH)D ................................................................................................................. 5   Parathyroid hormone (PTH)......................................................................................................7   Predictors of vitamin D status ...................................................................................................7   Dietary intake ............................................................................................................................................. 7   Season, latitude and sunlight exposure .............................................................................................. 8   Cardiorespiratory fitness, gender and obesity ................................................................................. 9   Heritability of s-25(OH)D levels ............................................................................................. 10   Autoimmune diseases and vitamin D .................................................................................... 10   Main present study: 7-year-old children 2006 .................................................................... 11   Icelandic Infant Nutrition Prospective Cohort: Intake at 6 years of age 2011. Comparison to present cohort ................................................................................................ 12   Summary ..................................................................................................................................... 12  

Methods.......................................................................................................................14   Statistical analysis of the additional results on intake of 7-year-olds and comparison between cohorts.......................................................................................................................... 14   Author contribution .................................................................................................................. 15  

Manuscript..................................................................................................................16   Insufficient autumn vitamin-D intake and low vitamin-D status in 7-year-old Icelandic children. ..................................................................................................................... 16  

Additional results .......................................................................................................40   The vitamin D intake and status of 7-year-olds - gender and fish liver oil intake ...... 40   Comparison of intake between cohorts of 7-year-olds in 2006 and 6-year-olds in 2011 ........................................................................................................................................................ 42  

Discussions and conclusion .......................................................................................45   Future perspectives....................................................................................................50   References...................................................................................................................51  

i  

I. Ágrip Markmið: Markmiðið var að rannsaka D-vítamínneyslu í fæði og D-vítamínbúskap 7 ára íslenskra skólabarna á haustmánuðum, september til nóvember 2006. Tengsl við líkamsþyngdarstuðul og þrek voru einnig könnuð. Mataræði 7 ára barna 2006 var einnig borið saman við mataræði 6 ára barna frá 2011 til að slá mati á hugsanlegan Dvitamínbúskap barna í dag. Aðferðir: Þriggja daga fæðuskráningum var safnað með jöfnu millibili frá september til nóvember (vika 36-46). Blóðsýni voru tekin eftir næturföstu og þrek var mælt með þrekhjóli. Fæðu- og næringarefnainntaka var reiknuð út og blóðgildi (s)-25(OH)D og kalkkirtilshormóns (PTH) greind. Ófullnægjandi D-vítamínbúskapur barna er skilgreindur sem