Hormones in our food supply?

During a recent family trip, we had the pleasure of dining at an upscale restaurant promoting all-natural, hormone-free, and antibiotic-free meats. Sounds…..confusing, right? At first thought, these claims may sound great, but if you look closer you may begin to wonder. What exactly does “natural” mean? (Spoiler alert: Nothing! This claim is not regulated by the government and both USDA/FDA have offered only vague guidelines) Don’t animals have hormones too, just like us? What kinds of antibiotics are used in animals, and why are they bad? Well, dear reader, continue on for some myth-busting facts.


Let’s start with hormones. First of all, what are hormones? Many of us remember learning about these body-changing chemicals in our middle school health classes. Hormones are messengers that regulate functions such as growth and development, metabolism, and more by acting on receptors in specific sites of our body. Not so scary after all, right? And yes, animals need hormones too, just like us, for normal healthy growth. However, what many people fear is that companies are pumping livestock full of added, synthetic hormones and chemicals to increase growth and create larger animals for higher profit. What they don’t realize is that added hormones are not legal in much of our food supply and have not been for over 50 years (US FDA). You may be surprised to learn, for example, that chickens have grown larger in recent years due to factors such as improved veterinary care and nutrition, not chemicals.


First, let’s start with the legal facts. According to the United States Food and Drug Administration, steroid growth hormones are NOT approved for use in dairy cattle, veal, poultry, or pigs (US FDA). This means that any package of chicken breast or pork chop claiming to be free of added hormones can be misleading to consumers. The claim is not untrue but can be confusing to a consumer who may not understand the current regulations in place. This can put another meat producer who did not make this claim on the label at risk of losing sales.



It is important to know that steroid growth hormone drugs ARE approved for use in beef cattle and sheep. This includes hormones such as estrogen, progesterone, and testosterone in both natural and synthetic forms (US FDA). These hormones are inserted behind the ear of the animal at certain points in the growth stage (US FDA). The ear is chosen as the best location for insertion because it does not enter the food supply. Farmers are also required to adhere to a “withdrawal period” of zero days, meaning that the meat must be safe for consumption and meet the regulatory requirements at any time (US FDA). Each of these measures ensures that you and your family are not exposed to excess hormones. Extensive studies have been performed to determine the maximum allowable level that is safe for human consumption, and have proven they are safe for use in both humans and the animals, themselves. These hormones help increase the animal’s growth rate and increase the efficiency of the feed (US FDA). This means you can grow larger cows with more meat using fewer resources. This is an important consideration in our ever-growing world.

Before we delve further into the details, let’s take a step back. As a good scientist, you should always be curious enough to ask yourself, “Why?” Why are hormones used in beef cattle and sheep, but not other sources of meat?

To answer this question, it is important to remember where our food comes from; a chicken breast was once a living, breathing animal, an animal that is much different than a large cow. There are a few reasons why added hormones do not benefit the chicken industry.  Broiler chickens (the most common commercial chicken) are typically between 6-8 weeks of age at the time of harvest. To mimic a chicken’s natural hormone release, a farmer would have to inject each chicken with hormones roughly every 3 hours during this grow-out stage (Business Insider). Considering the size of a typical flock (around 50,000-100,000 chickens), this would be logistically impossible on a commercial scale! But you’ve probably noticed that chickens today are much larger than they used to be. Why?

  1. Genetics: Selective breeding programs have allowed scientists and farmers to choose larger birds that grow quickly and have the most desirable traits (Think: Darwin and natural selection through science)

  2. A better understanding of nutritional needs has optimized the feed to include all the nutrients a developing bird needs in the most efficient way possible

  3. Controlling a chicken’s environment allows the birds to stay healthy and prevents disease, thus allowing them to grow larger

Scientists have spent over 60 years studying poultry and implementing advanced nutrition and veterinary methods that will raise birds faster and more efficiently. If you are interested in learning more check out this great resource from the University of Arkansas. Hormones in our Poultry: Is it for Real?

Cows and sheep are largely different animals in terms of growth and how they are raised on the farm. They have much longer periods of growth prior to slaughter and their environment may not be as easily controlled. In beef, specifically, there is a current trend for grass-fed cows. This means the farmer loses control of the nutrients entering the cow.  The cows are also exposed to a higher potential for disease when roaming.

Studies have shown there are no significant health effects to humans or to the animals treated. The hormones used are not biologically active after being processed by the human gut. This is because this type of hormone is a protein hormone. Once a human ingests the hormone, the protein is processed by the gut and is then inactive in the body. This also explains why diabetics must inject insulin and do not have an oral option.


rbST Claim MilkYou may have also heard of rbST or rBGH. You can easily find labels in the supermarket proclaiming their milk or yogurt was produced from cows not treated with rbST. Here’s the asterisk: studies have shown there is no significant difference in the milk produced from cows treated with rbST and those not treated. So, what exactly is it? Recombinant bovine somatotropin (rbST) or recombinant bovine growth hormone (rBGH) are synthetic versions of the natural hormones produced in cows to regulate lactation.  The use of these hormones can increase lactation by 10-15% (National Institutes of Health).

Because rBST is not a human hormone, it cannot interact with our receptors and is not recognized by the human body. Therefore, it is unable to cause adverse health effects (American Cancer Society). Furthermore, this type of hormone is actually a protein-type hormone. This means it is broken down in the digestive system and becomes inactive. This is similar to the use of insulin in humans and is the reason the hormone must be injected. The use of rBST has been studied extensively by multiple scientific groups over the last 50 years and has been approved in over 20 countries (Bauman). The results of these studies show no adverse health effects in humans or cows. Cows naturally produce this hormone, and studies have proven milk from cows treated with rbST exhibits the same levels of the hormone as milk produced by cows not treated (Bauman). That means that no matter where your milk comes from, you are consuming roughly the same amount of hormones in each glass.

Here’s a great resource for anyone who has further questions. Facts about Recombinant Bovine Somatotropin (rbST)


Concerns regarding the potential effects of growth hormones on wildlife downstream of cattle farms have recently surfaced within the last several years. It was initially believed that hormones were easily broken down and posed no effects on aquatic life or the environment (Renner). However, recent studies have found new evidence that fish and aquatic life may become negatively affected by higher levels of hormones in the water (Renner). What remains to be determined is whether the environment downstream of farms using added hormones are at an increased risk than those not using the hormones (Renner).   At this time, authorities have determined all approved hormone additives to have “no significant impact” on the environment.  I plan to keep up to date with current research regarding these concerns as more studies are performed.

In the case of dairy farms, the use of rbST in cows has greatly helped to reduce the carbon footprint of dairy farms. Through utilization of this technology, each cow is able to produce an additional 10 pounds of milk per day (Bauman). By increasing the yield of each cow, less food and land are needed for production; less fertilizer is needed to grow the food to feed the cows. Farmers may even have the ability to reduce the need for the number of cows in their herd, and thus decrease the amount of methane produced in the environment. What this equates to is an 8-9% reduction in carbon footprint per gallon of milk produced (Bauman)! This has a very positive impact on the environment, an area of growing concern in our society.


As we are all well aware, human populations have skyrocketed in the last century. Today, there are roughly 7.6 billion people in the world. In less than 100 years, the population is estimated to hit roughly 11.8 million. Currently, the world is facing a global hunger crisis that affects an estimated 815 million people in the world; that’s 1 in 9 people that do not have enough food already today (WFP).  The number of resources on Earth will remain the same, so we must act now to utilize our resources in the most efficient way possible so everyone receives the food and nourishment they deserve.

Did You Know? 

In addition to helping cows grow more efficiently, growth hormones also help keep beef prices down for the consumer. Through increased yields per cow, we can cut down on the amount of resources used. This helps both people and the environment. This can also be extremely important to a consumer with limited income, especially considering that beef is an important source of protein, B-vitamins, and iron.

You may think the use of hormones benefits only the profits of greedy companies. However, you may be surprised to learn that rbST was actually discovered during WWII as scientists tried to optimize milk production during a time of severe food shortages. Advances in science eventually led to the technology used today. We can use these advances to help feed an ever-growing world.


Used responsibly, hormones can help us optimize our resources and cut down on environmental impacts, land usage, and even consumer prices. Hormones are messengers in the body that regulate many processes. Growth hormones are approved only in beef cattle and sheep, no other animal. Studies have confirmed these hormones to be safe in both humans and animals.


  • Growth hormones are not approved for use in much of our livestock
    • Steroid hormones are approved for use ONLY in beef cattle and sheep
    • rbST is approved to increase milk production in dairy cows.
  • Scientific studies have found no evidence of negative health effects to humans or animals
  • Hormones help produce more food with fewer resources


  • Environmental consequences need more investigation
  • rbST can cause mastitis in cows, leading to the need for antibiotics



Remember, it’s up to you to research trusted, credible sources and make your own informed decisions. My intent with this blog is to help you understand some of the facts of our food supply and to get you thinking from a different perspective than you may be accustomed to. All the sources used in this blog post are listed below. I encourage you to go check them out for yourself and see what you think!


  1. “Steroid Hormone Implants Used for Growth in Food-Producing Animals.” US Food and Drug Administration. 12 October 2017 https://www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation/ucm055436.htm
  2.  “Bovine somatotropin.” NIH Technol Assess Statement Online. 1990 Dec 5-7 [cited 2018 01 07]; (7):16.
  3. “Recombinant Bovine Growth Hormone.” American Cancer Society. 10 September 2014. https://www.cancer.org/cancer/cancer-causes/recombinant-bovine-growth-hormone.html
  4. Bauman, Dale E. “Facts about Recombinant Bovine Somatotrophin.” Cornell University. Cited: 10 January 2018  https://ansci.cals.cornell.edu/sites/ansci.cals.cornell.edu/files/shared/documents/Recombinant%20Bovine%20Somatotropin_v3.pdf
  5. November 5-14, 2013 Affirmation of the human food safety of recombinant bovine somatotropin by the Joint Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Expert Committee on Food Additives, Seventy-Eighth report, pages 70-78 
  6. Watkins, Susan., Clark, Dustan F., Thaxton, Yvonne. “Hormones in our Poultry: Is It for Real?” University of Arkansas Division of Agriculture Research & Extension. Cited 16 January 2018. https://www.uaex.edu/publications/PDF/FSA-8007.pdf
  7. Jeong, Sang-Hee et al. “Risk Assessment of Growth Hormones and Antimicrobial Residues in Meat.” Toxicological Research 26.4 (2010): 301–313. PMC. Web. 19 Jan. 2018.
  8.  “Zero Hunger.”  World Food Programme. http://www1.wfp.org/zero-hunger
  9. Renner, Rebecca. 2002. “Do Cattle Growth Hormones Pose an Environmental Risk?” Environmental Science and Technology. https://pubs.acs.org/doi/pdfplus/10.1021/es022301%2B


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