{"id":6009,"date":"2026-10-19T09:48:22","date_gmt":"2026-10-19T09:48:22","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-naeringarfraedi-birna-thorisdottir\/"},"modified":"2026-10-19T09:48:22","modified_gmt":"2026-10-19T09:48:22","slug":"doktorsvorn-i-naeringarfraedi-birna-thorisdottir","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-naeringarfraedi-birna-thorisdottir\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed n\u00e6ringarfr\u00e6\u00f0i &#8211; Birna \u00de\u00f3risd\u00f3ttir"},"content":{"rendered":"<div class=\"field-items\">\n<div class=\"field-item even\" property=\"content:encoded\">\n<p>Fimmtudaginn 23. \u00e1g\u00fast ver Birna \u00de\u00f3risd\u00f3ttir doktorsritger\u00f0 s\u00edna \u00ed n\u00e6ringarfr\u00e6\u00f0i vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands. Ritger\u00f0in ber heiti\u00f0: D-v\u00edtam\u00edn \u00e1 nor\u00f0l\u00e6gum sl\u00f3\u00f0um \u2013 Inntaka og b\u00faskapur \u00edslenskra barna. Vitamin D in northern latitudes \u2013 Intake and status in Icelandic children.<\/p>\n<p>Andm\u00e6lendur eru dr. Lene Frost Andersen, pr\u00f3fessor vi\u00f0 H\u00e1sk\u00f3lann \u00ed \u00d3sl\u00f3, og dr. \u00c1sgeir Haraldsson, pr\u00f3fessor vi\u00f0 L\u00e6knadeild H\u00e1sk\u00f3la \u00cdslands.<\/p>\n<p>Umsj\u00f3narkennarar og lei\u00f0beinendur voru dr. Ingibj\u00f6rg Gunnarsd\u00f3ttir, pr\u00f3fessor vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands, og dr. Brynd\u00eds Eva Birgisd\u00f3ttir, pr\u00f3fessor vi\u00f0 s\u00f6mu deild. Auk \u00feeirra s\u00e1tu \u00ed doktorsnefnd dr. Geir Gunnlaugsson, pr\u00f3fessor vi\u00f0 F\u00e9lags- og mannv\u00edsindadeild H\u00e1sk\u00f3la \u00cdslands, og dr. Kim Fleischer Michaelsen, pr\u00f3fessor vi\u00f0 H\u00e1sk\u00f3lann \u00ed Kaupmannah\u00f6fn.<\/p>\n<p>Vigg\u00f3 \u00de\u00f3r Marteinsson, lektor vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild, stj\u00f3rnar ath\u00f6fninni sem fer fram \u00ed fyrirlestrarsal \u00dej\u00f3\u00f0minjasafnsins og hefst kl. 9:00.<\/p>\n<p><strong>\u00c1grip af ranns\u00f3kn <\/strong><\/p>\n<p>Markmi\u00f0 doktorsverkefnisins var a\u00f0 rannsaka matar\u00e6\u00f0i sex \u00e1ra barna (grein I), D-v\u00edtam\u00edninnt\u00f6ku og D-v\u00edtam\u00ednb\u00faskap vi\u00f0 12 m\u00e1na\u00f0a og sex \u00e1ra aldur (greinar II og III) og tengsl D-v\u00edtam\u00edns og matar\u00e6\u00f0is vi\u00f0 n\u00e6mi fyrir f\u00e6\u00f0u vi\u00f0 sex \u00e1ra aldur (grein IV). \u00de\u00e1tttakendur voru b\u00f6rn f\u00e6dd \u00e1ri\u00f0 2005 sem t\u00f3ku \u00fe\u00e1tt \u00ed ranns\u00f3kn \u00e1 n\u00e6ringu ungbarna \u00e1 fyrsta \u00e1ri og eftirfylgniranns\u00f3kn vi\u00f0 sex \u00e1ra aldur. Auk matar\u00e6\u00f0isuppl\u00fdsinga var styrkur 25-h\u00fddrox\u00fdv\u00edtam\u00edns D (25(OH)D) \u00ed sermi m\u00e6ldur vi\u00f0 12 m\u00e1na\u00f0a (n=76) og sex \u00e1ra aldur (n=139) og s\u00e9rt\u00e6k IgE m\u00f3tefni fyrir f\u00e6\u00f0u voru m\u00e6ld vi\u00f0 sex \u00e1ra aldur (n=144). Matar\u00e6\u00f0i sex \u00e1ra barna samr\u00e6mdist ekki r\u00e1\u00f0leggingum hva\u00f0 var\u00f0ar gr\u00e6nmeti, \u00e1vexti, fisk, heilkornabrau\u00f0 og trefjar\u00edkar kornv\u00f6rur og D-v\u00edtam\u00ednb\u00e6tiefni. Mi\u00f0gildi D-v\u00edtam\u00edninnt\u00f6ku var h\u00e6rra vi\u00f0 9-12 m\u00e1na\u00f0a aldur (8,7 \u00b5g\/d) en vi\u00f0 sex \u00e1ra aldur (4,9 \u00b5g\/d, p&lt;0,01). Me\u00f0alstyrkur D-v\u00edtam\u00edns \u00ed sermi vi\u00f0 12 m\u00e1na\u00f0a aldur var 98\u00b132 nm\u00f3l\/L, D-v\u00edtam\u00ednb\u00faskapur 92% barna var metinn fulln\u00e6gjandi og ekkert \u00feeirra meti\u00f0 me\u00f0 D-v\u00edtam\u00ednskort. Me\u00f0alstyrkur D-v\u00edtam\u00edns var l\u00e6gri vi\u00f0 sex \u00e1ra aldur (57\u00b118 nm\u00f3l\/, p&lt;0.01), 30% barna h\u00f6f\u00f0u \u00f3fulln\u00e6gjandi D-v\u00edtam\u00ednb\u00faskap og 6% voru me\u00f0 D-v\u00edtam\u00ednskort. H\u00e6rri D-v\u00edtam\u00edninntaka vi\u00f0 12 m\u00e1na\u00f0a aldur og notkun D-v\u00edtam\u00ednb\u00e6tiefna vi\u00f0 sex \u00e1ra aldur tengdust fulln\u00e6gjandi D-v\u00edtam\u00ednb\u00faskap og minni h\u00e6ttu \u00e1 n\u00e6mi fyrir f\u00e6\u00f0u vi\u00f0 sex \u00e1ra aldur. L\u00edkur \u00e1 n\u00e6mi jukust ef byrja\u00f0 var a\u00f0 gefa fasta f\u00e6\u00f0u fyrir 4 m\u00e1na\u00f0a aldur. Ni\u00f0urst\u00f6\u00f0urnar benda til \u00feess a\u00f0 \u00e1taks s\u00e9 \u00fe\u00f6rf svo a\u00f0 \u00edslensk b\u00f6rn fylgi betur r\u00e1\u00f0leggingum um matar\u00e6\u00f0i, \u00fear \u00e1 me\u00f0al um notkun D-v\u00edtam\u00ednb\u00e6tiefna. \u00de\u00e6r benda til \u00feess a\u00f0 heilbrig\u00f0 \u00edslensk b\u00f6rn sem fylgja r\u00e1\u00f0leggingum, \u00fe.e.a.s. f\u00e1 10 \u00b5g af D-v\u00edtam\u00edni \u00e1 dag, s\u00e9u a\u00f0 \u00f6llum l\u00edkindum me\u00f0 fulln\u00e6gjandi D-v\u00edtam\u00ednb\u00faskap. \u00d3fulln\u00e6gjandi D-v\u00edtam\u00ednb\u00faskapur og D-v\u00edtam\u00ednskortur var hins vegar algengur me\u00f0al sex \u00e1ra barna \u00ed ranns\u00f3kninni vegna l\u00edtillar D-v\u00edtam\u00edninnt\u00f6ku. Mikilv\u00e6gt er a\u00f0 fylgjast me\u00f0 matar\u00e6\u00f0i og D-v\u00edtam\u00ednb\u00faskap \u00edslenskra barna og beina sj\u00f3num b\u00e6\u00f0i a\u00f0 l\u00e1gum og h\u00e1um bl\u00f3\u00f0gildum. \u00de\u00f6rf er \u00e1 frekari ranns\u00f3knum \u00e1 tengslum D-v\u00edtam\u00edns og matar\u00e6\u00f0is vi\u00f0 n\u00e6mi og ofn\u00e6mi.<\/p>\n<p><strong>Abstract<\/strong><\/p>\n<p>The aim of this Ph.D. thesis was to study the diet of 6-year-old children (paper I), their vitamin D intake and vitamin D status at 12 months and 6 years (papers II and III) and compare vitamin D and feeding in infancy between 6-year-old children IgE-sensitized to food allergens and non-sensitized children (paper IV). The study population were children born year 2005 who participated in a study on infant nutrition, with follow up at 6 years. Additionally to dietary data, serum 25-hydroxyvitamin D (25(OH)D) was measured at 12 months (n=76) and 6 years (n=139) and serum-specific IgE-antibodies against food measured at 6 years (n=144). Adherence to dietary guidelines among 6-year-old children was low, especially for fruit and vegetables, fish, wholegrain bread and other fiber-rich cereals and vitamin D supplements. Total vitamin D intake was higher at 9-12 months than at 6 years (the median intakes were 8.7 \u00b5g\/d vs. 4.9 \u00b5g\/d, respectively, p&lt;0.01). The mean 25(OH)D concentration at 12 months was 98\u00b132 nmol\/L, with 92% of infants defined as having sufficient status and none deficient. At 6 years, vitamin D status was lower than in infancy (57\u00b118 nmol\/L), 30% of children were vitamin D insufficient and 6% deficient. Higher vitamin D intake at 12 months and vitamin D supplement use at 6 years were associated with vitamin D sufficiency and a lower risk of sensitization. Introduction of solid foods prior to 4 months was associated with increased risk of sensitization. The results indicate that a public health effort among Icelandic children is needed to increase adherence to dietary guidelines, including vitamin D supplement use. Healthy Icelandic infants and children receiving the recommended 10 \u00b5g\/d vitamin D are likely to be vitamin D sufficient. Vitamin D insufficiency and deficiency may however be prevalent among 6-year-old children due to insufficient intake. Monitoring of diet and vitamin D status among Icelandic infants and children is important, looking both at low and high vitamin D levels. Further studies are needed on the associations of vitamin D and diet with food sensitization and allergy.<\/p>\n<p><strong>Um doktorsefni\u00f0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/strong><\/p>\n<p>Birna er f\u00e6dd \u00ed Reykjav\u00edk \u00e1ri\u00f0 1988. H\u00fan lauk st\u00fadentspr\u00f3fi af n\u00e1tt\u00farufr\u00e6\u00f0ibraut Menntask\u00f3lans vi\u00f0 Hamrahl\u00ed\u00f0 \u00e1ri\u00f0 2007, BS-pr\u00f3fi \u00ed n\u00e6ringarfr\u00e6\u00f0i fr\u00e1 H\u00e1sk\u00f3la \u00cdslands \u00e1ri\u00f0 2011 og MS-pr\u00f3fi \u00ed n\u00e6ringarfr\u00e6\u00f0i fr\u00e1 sama sk\u00f3la \u00e1ri\u00f0 2013. Me\u00f0fram doktorsn\u00e1minu hefur h\u00fan starfa\u00f0 sem stundakennari vi\u00f0 H\u00e1sk\u00f3la \u00cdslands og verkefnisstj\u00f3ri vi\u00f0 Ranns\u00f3knastofu \u00ed n\u00e6ringarfr\u00e6\u00f0i. \u00cd dag starfar Birna vi\u00f0 fr\u00e6\u00f0slu og forvarnir hj\u00e1 Krabbameinsf\u00e9laginu og sem stundakennari vi\u00f0 H\u00e1sk\u00f3la \u00cdslands. Foreldrar Birnu eru \u00de\u00f3rir \u00d3skarsson \u00edslenskufr\u00e6\u00f0ingur og Krist\u00edn \u00de\u00f3rsd\u00f3ttir t\u00f6lvunarfr\u00e6\u00f0ingur. Birna er gift Ing\u00f3lfi Birgissyni lyfjafr\u00e6\u00f0ingi. \u00deau b\u00faa \u00ed K\u00f3pavogi \u00e1samt b\u00f6rnum s\u00ednum, Bjarka \u00de\u00f3r og An\u00edtu Au\u00f0i.<\/p>\n<\/div><\/div>","protected":false},"featured_media":1242,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2018-08-23T09:00:00+00:00","_phd_date_end":"2018-08-23T12:00:00+00:00","_phd_location":"Fyrirlestrarsalur \u00dej\u00f3\u00f0minjasafnsins","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"D-v\u00edtam\u00edn \u00e1 nor\u00f0l\u00e6gum sl\u00f3\u00f0um \u2013 Inntaka og b\u00faskapur \u00edslenskra barna. 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