“…In countries around the equator, UV light and, therefore, the production of vitamin D, is constant throughout the year (Glerup et al, 2000). However, seasonal variation in UV intensity, as occurs both far North and South of the equator, results in marked variation in vitamin D status throughout the year, with highest concentrations found in late summer and markedly lower concentrations observed in late winter (McLaughlin et al, 1974;McKenna, 1992). This seasonal pattern is apparent in all European countries, but is particularly evident in northern European countries, including the UK and Ireland, which are located at 50-601N (Ovesen et al, 2003;Zittermann, 2003).…”