Are there hormones in milk?

Hormones occur naturally everywhere – even in plants. We all need hormones to trigger important functions in our bodies.

All milk, whether conventional or organic, has small amounts of natural hormones. These hormones are harmless – our bodies simply break them down and discard them.

What about synthetic hormones?

Some dairies treat cows with the FDA-approved rbST, a synthetic version of a common growth hormone. This hormone helps cows produce more milk, while reducing waste. 

The hormone has been used for more than 20 years, and heavily researched. Studies and reviews from organizations like the National Institutes of Health, the World Health Organization, the American Medical Association and Cornell University all agree that milk from cows treated with rbST is harmless to humans – and is just as wholesome and safe as milk from untreated cows.1-3

You might see dairy products marked “No rbST” in your grocery aisle, but this is a response to hype – it is not a health or safety issue. Rest assured that no matter which brand of milk you place in your cart, you are getting a safe and wholesome product.

But does it hurt the cows?

You may have heard the rumor that rbST increases the risk of mastitis in dairy cows, but an FDA Advisory Council studied the numbers and concluded that factors such as the season and the age of the cow were more likely to be the cause of any increased numbers of mastitis. 

Cows diagnosed with mastitis are separated from the rest of the herd while they are nursed back to health, and their milk is not sold until they are healthy again and completely free of antibiotics.

No matter which cows milk you choose at the grocery store, rest assured that you are getting a safe, wholesome, delicious product for your family.

1. National Dairy Council. 2007 Mar. Scientific Status Report #19: Hormones and Milk. Accessed 2012 January.
2. USDHHS/NIH. 1991. NIH Technology Assessment Conference statement on bovine somatotropin. J Am Med Assoc. 265:1423-5.
3. Vicini, J, et al. 2008. Survey of retail milk composition as affected by label claims regarding farm-management practices. J Am Diet Assoc. 108:1198-1203.

By Susan Allen

Susan grew up on a farm in northwest Oklahoma and has over 30 years of experience working in agriculture. She has been part of the Dairy MAX team since 2007 and has worked with schools, health and wellness professionals and farmers. When she's not working, Susan is usually helping one of her kids with a 4-H project. Learn more about Susan

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