hello world!
Published: June 15, 2023

Untangling the Controversy: rBST-treated Milk and What It Means for Your Health

Key points

  • rbST, or recombinant bovine somatotropin, is a protein hormone naturally produced in cattle and used in some dairy farms to increase milk production. It's synthetically produced using biotechnology and is approved for use in dairy cows by the FDA.
  • Numerous international health organisations have confirmed that milk from rbST-treated cows is safe for human consumption.
  • While rbST is a hormone in cattle, it does not have any biological activity in humans. It's broken down in our gastrointestinal tract, meaning you aren't actively ingesting functioning hormones when consuming milk from rbST-treated cows.
  • The safety of rbST milk doesn't make rbST-free milk a better choice in terms of safety
  • While there are some observed side effects in cows, they can be managed effectively and differs in production systems. However, continuous monitoring ensures the safety of these animals.

You are at the milk fridge in your local shop and are confronted with a choice: rBST free or regular? Will it affect your health, your children's health and development, will you grow an extra arm? A thousand questions arise. To start with the science, let's define what rBST is. It is a synthetic version of a natural hormone found in cattle, recombinant bovine somatotropin (rBST) or bovine growth hormone (BGH), produced via biotechnology and since its approval by the U.S. Food and Drug Administration (FDA) in 1993, it's been used in various countries to increase milk production in dairy cows. 

Is it safe? 

The reason you have all those questions is about the initial uncertainty and concerns about rBST and its potential impact on human health. Your questions answered: according to scientific reviews and over 20 years of commercial use, there is no conclusive evidence linking rBST/BGH to increased risk of cancer in humans. The main reason for this is that bovine growth hormone, whether natural or synthetic, doesn't interact with human growth hormone receptors. Furthermore, any additional BGH from rBST-treated milk is broken down by our digestive system, just like any other protein we consume.

Another concern came from the potential increase of insulin-like growth factor (IGF-1) due to milk from rBST-treated cows. Humans naturally produce IGF-1 and excess levels of this hormone in our bodies can stimulate cell growth, but studies note that IGF-1 levels in milk fall within the normal range, whether the milk comes from rBST-treated cows or not.

Does it affect the cows?

In most production system, rBST works for the farmer and the animals, but in some dairy production systems, the use of rBST has shown some adverse health effects in cows, including higher rates of mastitis (udder infections), foot problems, and injection site reactions. These health issues often require additional antibiotic treatment, which previously raised concerns about the potential development of antibiotic-resistant bacteria, but no connection has been made between antibiotic use in rBST-treated cows and antibiotic resistance in humans. Regardless, if traces of antibiotics were found in milk it would be illegal to sell it to the public, meaning antibiotic use on farm isn't a concern for human health. In terms of animal welfare, farmers who do see adverse effects on their cows stop using it altogether, both due to welfare concerns and the cost of reduced production and treating sick animals. 

What's the Bottom Line?

The consensus from regulatory bodies is that milk from rBST-treated cows are safe for human consumption, based on the fact that it doesn't interact with human growth hormone receptors (meaning it will be digested like any other protein) and that there aren't increased levels of IGF-1 in milk from cows treated with rBST.  The use of rBST provides benefits in terms of increased milk production, the potential impacts on animal welfare and the development of antibiotic-resistant bacteria are factors that deserve ongoing research.

Despite the controversies, one thing remains clear: milk and dairy products provide essential nutrients and benefits in health maintenance and the prevention of chronic diseases. Whether you choose to consume milk from rBST-treated cows or not, dairy remains a valuable part of a balanced diet. But rest assured, based on the evidence out there, your next decision on cow milk just became a whole lot easier. 



American cancer Society. 2014. Recombinant Bovine Growth Hormone. Link: https://www.cancer.org/cancer/risk-prevention/chemicals/recombinant-bovine-growth-hormone.html

Collier & Bauman. 2014. Update on human health concerns of recombinant bovine somatotropin use in dairy cows. J Anim Sci, 2014 Apr;92(4):1800-7. doi:10.2527/jas.2013-7383. Epub 2014 Feb 10. Link: https://pubmed.ncbi.nlm.nih.gov/24663163/

Dohoo, I.R. et al. 2003. A meta-analysis review of the effects of recombinant bovine somatotropin. Can J Vet Res. 2003 Oct; 67(4): 252–264. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC280709/

FDA. 2023. Bovine Somatotropin (bST). Link: https://www.fda.gov/animal-veterinary/product-safety-information/bovine-somatotropin-bst


In progress


Mrs. Enrike Maree (BScAgric)