Unlike steroid hormones, which can be taken orally, rBGH and IGF must be injected to have any effect. That’s because the process of digestion destroys these “protein” hormones. So drinking milk from hormone-treated cows doesn’t transfer the active form of these chemicals to your body. However, there is one ethical downside to consider: It’s not good for the cows. Canadian researchers discovered that cows given hormones are more likely to contract an udder infection called mastitis.

Not unless you’re injecting the milk. Here’s the full story: In 1993 the FDA approved the use of recombinant bovine growth hormone (rBGH) in cattle. This practice resulted in greater milk production at less cost to the dairy farmer, a savings that has been passed on to you at your local supermarket. But it has also sparked much controversy, because rBGH boosts milk’s concentration of insulin-like growth factor (IGF), a hormone that’s been linked to cancer.