Many are making claims (perhaps as a marketing technique to increase profits) that milk produced from cows containing rbST is less healthy than conventionally produced milk. Milk from cows given supplemental bST contains no more bST than milk from cows not given the supplement, so the hormone itself is not a concern.
It is true however, that milk from cows that have been administered supplemental rbST contains higher levels of IGF-1 ( insulin growth factor-1). Research indicates that this level of increase is small.
In fact, the normal variation in naturally occurring IGF-1 levels among cows is much greater than this difference. Due to natural variation, it is just as likely that you will find a random organic cow that has much higher levels of IGF-1 than a random cow treated with rbST. With that said, should we be concerned with IGF-1 anyway?
Quote: “The amount of IGF-1 in milk is insignificant compared to the amount already produced in our bodies every day,” he asserts. “We swallow it in our saliva, and the amount we swallow daily is equal to the amount of IGF-1 in 95 quarts of milk. The amount produced in our whole body every day is equal the amount in 3,000 quarts of milk.”
Bauman further explains—and the American Cancer Society concurs—that there is no cause-and-effect chain linking bST, high levels of IGF-1, and cancer. “In fact, elevated levels are actually to be expected [when cancer is present] because IGF-1 is involved the turnover and repair of cells, including tumor cells.”
*Dale Bauman, professor of nutritional science and of animal science at Cornell University