Iodine concentration in Norwegian milk has declined in the last decade

Abstract

To evaluate the iodine (I) level in Norwegian milk, the I concentration was determined in 104 dairy tanker milk samples collected from 19 milk tours in different areas of Norway, throughout the year 2008. The I concentration in milk from indoor feeding was 122 µg L⁻¹ and higher than in milk from the summer season, being 92 µg L⁻¹. The weighted average mean I concentration throughout the year was 114 µg L⁻¹ milk. The results showed that the I concentration in milk from the winter season 2008 has been reduced to nearly the half during the last decade, from 232 µg I L⁻¹ in milk collected in the winter season in 2000. The I concentration in milk from the summer season is at the same level as a decade ago. The reason for the reduction in I in milk produced during the winter season is not known.

Keywords:

• Dairy milk
• concentrate
• grass intensive
• indoor feeding
• iodine
• pasture
• production system
• region
• Norway

Acknowledgements

The work was supported by the Norwegian University for Life Sciences and the national dairy company TINE SA. The authors also thank Cato Wendell and the staff at the Isotope Laboratory, The Norwegian University for Life Sciences for the determination of iodine in milk.