found only slight differences in the nutritional composition of conventional, BST-free and organic milk.
Samples of each type of milk were collected from all 48 contiguous states last fall. The samples were then analyzed for nutritional, bacterial and hormonal content.
Only minor differences were found. None of the samples contained antibiotic residues. Conventional milk had lower bacteria counts. The differences were statistically different, but there was no biologically-significant difference.
Protein concentration was higher in organic milk than either conventional or BST-free. "Lower-producing cows typically have greater concentration of protein in milk, and cows managed in organic systems are usually lower producing….” say the authors.
Concentrations of BST were not different among the three milk types. Concentrations of IGF-1 were similar for conventional and BST-free, and lower in organic milk. The authors speculate this could be due to ultra-pasteurization of the organic milk, which destroys IGF-1. And even if the organic milk is lower in IGF-1, the difference is 0.003% of the IGF-1 produced daily by humans.