Do IGF-1 concentrations increase in milk from rbST-treated cows?
Does IGF-1 survive digestion? And, What are the possible adverse health effects of increased IGF-1 in milk? Do IGF-1 concentrations increase in milk from rbST-treated cows? JECFA addressed this question in its 1993 report and concluded that the best studies then available did not indicate an increase in average IGF-1 levels. However, a study by Monsanto did not become available to the public until after JECFA completed its review. We have conducted a new analysis of the data, considering both the latest Monsanto study and all earlier evidence on this question. We conclude that the weight of evidence indicates that rbST use does increase IGF-1 levels in milk, substantially. In our judgment, the most important question is no longer whether IGF-1 levels increase, but rather how much they increase, on average. The latest Monsanto study, and five of the seven studies previously reviewed by JECFA, found an increase in IGF-1 levels. In five of these six studies, the increase was statistically
