1 National Food Institute, Technical University of Denmark2 Division of Nutrition, National Food Institute, Technical University of Denmark3 Division of Food Chemistry, National Food Institute, Technical University of Denmark4 Aalborg University5 Bispebjerg University Hospital6 Capital Region of Denmark7 Slagelse Hospital
Fortification with the essential trace element iodine is widespread worldwide. In the present study, results on iodine excretion and intake of iodine-rich foods from a cross-sectional study carried out in 2004-5, 4 to 5 years after the implementation of mandatory iodine fortification, were compared with data in a study carried out in 2008-10. The 2008-10 study was a follow-up of a cross-sectional study carried out before iodine fortification was implemented. Participants in the cross-sectional studies were randomly selected. Both studies were carried out in the cities of Aalborg and Copenhagen in Denmark. The median urinary iodine concentration decreased in women from 97 μg/l (n 2862) to 78 μg/l (n 2041) (P<0·001). The decrease persisted after adjustment for age, city and education, and if expressed as estimated 24 h iodine excretion. The prevalence of users of iodine containing dietary supplements increased from 29·4 to 37·3 % (P<0·001). The total fluid intake increased in women (P<0·001), but the intake of other iodine-rich foods did not change. The median urinary iodine concentration did not change in men (114 μg/l (n 708) and 107 μg/l (n 424), respectively), while the total fluid intake decreased (P= 0·001). Iodine content was measured in milk sampled in 2000-1 and in 2013. The iodine content was lower in 2013 (12 (sd 3) μg/100 g) compared with that in 2000-1 (16 (sd 6) μg/100 g) (P<0·001). In conclusion, iodine excretion in women has decreased below the recommended level. The reason might probably, at least partly, be a decreased content of iodine in milk.
British Journal of Nutrition, 2014, Vol 112, Issue 12, p. 1993-2001
Adult; Aged; Animals; Cross-Sectional Studies; Denmark; Diet; Dietary Supplements; Energy Intake; Female; Food, Fortified; Humans; Iodine; Male; Middle Aged; Milk; Sex Factors; Fortification; Nutrient intake; Iodine content in milk