International Agency for Research on Cancer World Health Organization

The increasing breast, colorectal and prostate cancer mortality rates found with increasinglatitude by ecological studies in the USA and in Europe has been equated to lower vitamin D statuswith increasing latitude. We examined in Western, Northern and Southern Europe the associationbetween latitude of residence and serum 25-hydroxyvitamin D levels. We performed a systematicsearch of published articles reporting serum 25-hydroxyvitamin D levels in apparently healthy adultEuropean populations. Using results of selected studies, we fitted a random effects model based onstandard deviations of means of serum 25-hydroxyvitamin D concentrations. Thirty-five studies wereincluded in the analysis, representing 114 estimates of mean serum 25-hydroxyvitamin D derivedfrom a total of 9,514 subjects 18 years old or more, including 1,887 males, 5,008 females, and 2,619subjects of unknown sex. Increase in latitude was statistically significantly associated with increase inserum 25-hydroxyvitamin D levels among subjects more than 65 years old. In younger subjects, nosignificant association with latitude was found. In subjects more than 65 years old, an increase in 10degrees in latitude of residence increases mean serum 25-hydroxyvitamin D by 11.8 nmol/L. BetweenEuropean countries, increase in latitude is associated with increase in serum 25-hydroxyvitamin Dconcentrations. Reasons other than vitamin D status may explain the relationship between increasinglatitude and cancer mortality rates observed in the USA and in Europe.