Milk Myth: The Growth Hormones in Milk are Bad for You

Myth: The Dairy Industry Adds Growth Hormones to Milk That are Bad for You

Milk Myth

Myth Buster: Milk from rBST treated cows is identical to milk from untreated cows.

All milk contains small amounts of naturally-occurring hormones. Bovine somatotropin (BST) or bovine growth hormone (BGH) is a naturally-occurring hormone in cows that helps them produce milk. rBST, a synthetic copy of this hormone, is sometimes given to cows by dairy farmers to boost milk production. BST (natural or synthetic) does not have any impact on human health, since it is species specific, 90 percent of it is destroyed by pasteurization, and the remaining trace amounts are completely broken down into inactive amino acids segments in the intestine—like any other protein.

Considerable testing was done before rBST was approved for use by dairy farmers in the early 1990s. Studies have shown that milk from rBST-treated cows is identical to milk from untreated cows1 and the Food and Drug Administration (FDA) deems the use of rBST in dairy cattle a safe practice.2 Since then, reviews by National Institutes of Health (NIH), World Health Organization (WHO)/Food and Agriculture Organization (FAO) and American Medical Association (AMA) have all supported FDA’s position that milk from rBST-treated cows is safe.3,4

Some people prefer to consume milk and dairy foods that were not produced with rBST. To meet their needs, some processors do not use it and label their milk and dairy foods as rBST free. However, consumers can feel confident that all milk produced and sold in the U.S.—with or without rBST—contains the same combination of nutrients and is pure and safe.2

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1Vicini J et al. J Am Diet Assoc 2008; 108:1198.
2Food & Drug Administration,, site Accessed 8/4/2011. Accessed 8/4/2011. Accessed 8/4/2011.