title: Effect of production system, supermarket and purchase date on the vitamin D content of eggs at retail.
abstract: The vitamin D content of eggs from three retail outlets was measured over five months to examine the effects of production system (organic vs. free range vs. indoor), supermarket and purchase date on the concentration of vitamin D3and 25-hydroxyvitamin D3. Results demonstrated a higher vitamin D3concentration in free range (57.2±3.1μg/kg) and organic (57.2±3.2μg/kg) compared with indoor (40.2±3.1μg/kg) (P<0.001), which was perhaps related to increased vitamin D synthesis by birds having more access to sunlight, while 25-hydroxyvitamin D3concentration was higher (P<0.05) only in organic eggs. The interaction (P<0.05) between system and supermarket for both forms of vitamin D may relate to some incorrect labelling. Concentration of 25-hydroxyvitamin D3was higher (P<0.05) in July and September than in August.The results indicate variations in vitamin D concentrations in eggs from different sources, thus highlighting the importance of accurate labelling.
authors.affiliation: Centre for Food, Nutrition and Health, University of Reading, Reading RG6 6AR, UK; Hugh Sinclair Unit of Human Nutrition and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading RG6 6AP, UK. Electronic address: jing.guo@pgr.reading.ac.uk.
authors.forename: Jing
authors.initials: J
authors.lastname: Guo
authors.affiliation: Centre for Food, Nutrition and Health, University of Reading, Reading RG6 6AR, UK. Electronic address: k.e.kliem@reading.ac.uk.
authors.forename: Kirsty E
authors.initials: KE
authors.lastname: Kliem
authors.affiliation: Centre for Food, Nutrition and Health, University of Reading, Reading RG6 6AR, UK; Hugh Sinclair Unit of Human Nutrition and Institute for Cardiovascular and Metabolic Research, University of Reading, Reading RG6 6AP, UK. Electronic address: j.a.lovegrove@reading.ac.uk.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Lovegrove
authors.affiliation: Centre for Food, Nutrition and Health, University of Reading, Reading RG6 6AR, UK. Electronic address: d.i.givens@reading.ac.uk.
authors.forename: D I
authors.initials: DI
authors.lastname: Givens
mesh_terms: D000818:Animals; D002112:Calcifediol / Q000032:analysis / Q000378:metabolism; D002645:Chickens; D002762:Cholecalciferol / Q000032:analysis* / Q000378:metabolism; D003132:Commerce / Q000592:standards* / Q000639:trends; D004531:Eggs / Q000032:analysis*; D000072480:Farms / Q000592:standards* / Q000639:trends; D006801:Humans; D013472:Sunlight; D013997:Time Factors; D006113:United Kingdom; D014807:Vitamin D / Q000032:analysis / Q000378:metabolism
chemical_list: D014807:Vitamin D; D002762:Cholecalciferol; D002112:Calcifediol
keywords: 25-Hydroxyvitamin D(3); Eggs; Vitamin D(3)