Once the undisputed mainstay of a healthful American diet, cow's milk is getting a second and third look these days. An area of great contention is rBGH (recombinant bovine growth hormone; also known as rBST, or bovine somatotropin), the synthetic -- and genetically engineered -- growth hormone that stimulates cows to produce about 10 percent more milk than normal. These cows get more udder infections and therefore need more antibiotics; their milk may contain antibiotic-resistant bacteria that can infect humans.
Some studies also show that milk from rBGH cows has higher than normal levels of a naturally occurring hormone, IGF-1, that's associated with breast, prostate, and colon cancers. The FDA claims that these hormones are destroyed by digestion, but many American dairy distributors and retailers refuse to sell milk from cows that have been given rBGH.
Ensure that you don't ingest any more hormones than necessary by purchasing milk and other dairy products that are labeled as rBGH-free (such as artificial growth hormone free); organicconsumers.org maintains a list of rBGH-free dairy products by state.
Avoid contributing to the growing problem of antibiotic-resistant bacteria by purchasing certified organic milk, which comes from cows that haven't been treated with antibiotics or rBGH. These animals have also been fed an organic grain-based diet and/or allowed to graze in pasture free of herbicides and most pesticides, so there are fewer contaminants in the milk. And grass-fed cows tend to be healthier and produce more nutritious milk. As another option, you can try organic soy and rice milks.