Roughly 17% of dairy cows are dosed with something called recombinant bovine growth hormone, or rBGH, sold under the trade name Prosilac. This is done so each cow will produce 7-8 more pounds of milk daily — about a gallon. Clearly this is good for the dairy farmer! But is it good for the cow? What about the human who consumes that milk?

Nobody ever claimed it was good for the cow. In fact, cows treated with rBGH are 25% more likely to develop mastitis and 55% more likely to develop lameness. That’s why the European Union doesn’t recommend its use and Canada has banned it altogether.

As for humans, there are no real studies. However — despite the FDA required label saying that treated milk is no different from non-treated milk — rBGH milk has “reduction in short-chain fatty acid and increase in long-chain fatty acid levels; increase in levels of a thyroid hormone enzyme; contamination with unapproved drugs for treating mastitis; and frequency of pus cells due to mastitis.” In addition, levels of IGF-1 (Insulin-like Growth Factor 1) in rBGH milk are 4 to 20 times what they are in conventional milk. IGF-1 is necessary for human growth hormone to work properly, but it is easily absorbed in humans, and excess levels are implicated in several cancers. Knowing all this, it’s hard to see how rBGH milk can possibly not have an effect on the human metabolism.

If you find this alarming, don’t panic. Even though much of our milk supply has been touched by this stuff, it isn’t that hard to avoid. For example, all of Trader Joe’s dairy products are rBGH free. Tillamook is an rBGH free brand — and they had to go to court to do it. Many organic dairy products shun the use of artificial hormones including rBGH. Wal-Mart stopped carrying products with rBGH almost 2 years ago. Even Kraft has bowed to consumer pressure and offers a no-rBGH line.