The Biggest Myth About rBST-Free Milk

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You probably didn't notice, but 2017 marked the "end of an era" in the dairy industry. At the closing of the year, a rare few dairy processors accepted milk produced by cows injected with recombinant bovine somatotropin, more commonly known as rBST. The quiet dwindling of rBST into obscurity is unfortunate because it was fueled by misinformation, fear, irrationality, and a widespread myth: that "rBST-free" milk is safe to drink while milk produced with the hormone's aid is not. In fact, there is no substantive difference between either products, and both are completely safe to drink.

Recombinant bovine somatotropin (rBST) is the commercially produced version of bovine somatotropin (BST), a protein hormone naturally produced in cows' pituitary glands. Both are identical but for a single extra amino acid in rBST. In the 1970s, Cornell scientists discovered that injecting cows with additional BST drastically increased dairy cows' milk production with no adverse effects. In the early 1980s, the companies Monsanto and Genentech teamed up to create rBST, which could be produced in vast quantities. For more than a dozen years, scientists extensively studied the hormone, dairy cows, and the resulting milk produced for safety, efficacy, and animal welfare. By 1994, the Food and Drug Administration recognized rBST's solid scientific standing and approved it for commercial sale. A small injection every two weeks of a plant oil formulation containing rBST could increase a cow's daily milk yield by ten pounds with no ill effects for the cow.

Yet, as milk produced by cows injected with this small amount of rBST slowly came onto the market, a campaign quickly formed to drive it out. Critics claimed that it was unnatural, of lesser quality, and contributed to breast cancer. They were misleading or wrong on all counts. Arguing "naturalness" is irrelevant and meaningless, with no bearing on the quality of a thing. Cyanide, for example, is natural to outer space and nature but you'd never want to drink it. Moreover, milk produced with the aid of rBST is no less nutritious. The only differences ever discovered were a possible 2% increase in butterfat and 1% increase in protein. Lastly, the breast cancer scare-mongering stemmed from the notion that rBST milk contains more of a hormone called insulin-like growth factor 1 (IGF-1), which is naturally produced by various tissues in the human body and may, as a side effect of its normal bodily functions, contribute to the risk of breast cancer. Milk produced with rBST does indeed have a little more IGF-1 than normal milk, but the difference is so small that the average milk-drinking adult would receive just 0.09% more IGF-1 than he or she already does from their own body.

With rBST, as well as other complicated issues where science and society collide, nuance matters. But consumers and activist groups didn't seem to be interested in honest, rational debate. In 2007, large chains Safeway, Chipotle, Kroger, and Starbucks dropped rBST-derived milk after consumer pressure, and over the past decade other businesses quietly followed suit. With little remaining demand, rBST is all but gone.

To be clear, rBST's resumé wasn't perfect. A 2003 meta-analysis showed that cows treated with the hormone were 25% more likely to develop mastitis – inflammation of the udder. They were also 40% more likely to fail to conceive and suffered a 55% higher risk of developing clinical signs of lameness. Cornell University Emeritus Professor Dale Bauman, one of the original researchers who pioneered the use of rBST, disputes those exact numbers, and also notes that these problems are common for higher milk-producing cows in general. He also argues that most of rBST's adverse effects were easily manageable at dairy farms. Bauman's statements are backed by other research groups.

Ultimately, there's little reason to mourn rBST – dairy producers don't need it to meet demand. But rBST's story is somewhat depressing because it is a glaring example of Americans' inability to parse the evidence on complicated issues in biotechnology. It leaves one wondering: What future world-changing advances will fall to ignorance, irrational fear, misunderstanding, and outright lies?

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