title: Iodine concentration in cow's milk and its relation with urinary iodine concentrations in the population.
abstract: OBJECTIVE
  The importance of milk intake to the supply of dietary iodine is not fully known. We therefore undertook a study in Spain of the iodine concentration in cow's milk and the impact of the frequency of milk consumption on urinary iodine concentrations in three study populations.
  
  
  METHODS
  We studied the iodine concentration in 362 samples of milk from 45 commercial brands and compared it with the milk iodine status in studies undertaken 17 years earlier. The epidemiologic studies were performed in three different places in the south of Spain: two in school-age children (N = 757 and N = 1205 children) and one in adults (N = 1051). A milk consumption questionnaire was given and urinary iodine concentrations measured.
  
  
  RESULTS
  The mean concentration of iodine in the milk rose from 1991 (117 ± 37 μg/L) to 2008 (259 ± 58 μg/L) (P < 0.001). The iodine concentration was greater in skimmed milk (273 ± 52 μg/L) than in semi-skimmed milk (254 ± 57 μg/L) or whole milk (251 ± 61 μg/L) (P < 0.0001). The winter samples had a greater concentration of iodine (270 ± 55 μg/L) than the summer samples (247 ± 58 μg/L) (P < 0.0001), independently of the type of milk. The urinary iodine concentrations in all three epidemiologic studies were significantly associated with the frequency of milk intake.
  
  
  CONCLUSIONS
  The concentration of iodine in cow's milk has risen over recent years, and it is higher in skimmed milk. The results also show that cow's milk is a relevant source of dietary iodine.
authors.affiliation: Servicio de Endocrinología y Nutrición, Hospital Regional Universitario Carlos Haya, Málaga, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: Soriguer
authors.forename: Carolina
authors.initials: C
authors.lastname: Gutierrez-Repiso
authors.forename: Stella
authors.initials: S
authors.lastname: Gonzalez-Romero
authors.forename: Gabriel
authors.initials: G
authors.lastname: Olveira
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Garriga
authors.forename: Ines
authors.initials: I
authors.lastname: Velasco
authors.forename: Piedad
authors.initials: P
authors.lastname: Santiago
authors.forename: Gabriella M
authors.initials: GM
authors.lastname: de Escobar
authors.forename: Eduardo
authors.initials: E
authors.lastname: Garcia-Fuentes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency / Q000652:urine*; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000737:chemistry*; D015995:Prevalence; D012621:Seasons; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007455:Iodine