Dairy Milk: Hormones and Antibiotics


On our quest to bring honest information, we are often torn apart by rather biased interpretations from the dairy council and the anti-milk campaigners. When it comes to issues as sensitive as synthetic hormones and antibiotics, mixed messages can be dangerous. We have chosen the conservative side, and pooled together hard facts as evidenced by scientific studies, in order to identify any true risks:

  • Bovine Growth Hormone, or BGH, is a natural occurring hormone in cows that stimulates the production of another hormone, IGF-1 (insulin-like growth factor-1). IGF-1 in turn initiates the production of milk.
  • The FDA approved the use of rBGH, a synthetic version of BGH, in 1993. The injection of rBGH into cows has become standard practice on many dairy farms, as it has the ability to unnaturally increase a cow’s output of milk by up to 20% (according to the rBGH manufacturer).
  • As a consequence, cows treated with rBGH produce greater levels of IGF-1. In fact, numerous studies have confirmed that cows treated with rBGH produce milk with 2 to 10 times the levels of IGF-1 found in an untreated cow’s milk
  • The IGF-1 found in cows is a bioidentical hormone to the IGF-1 produced by humans.
  • Dairy supporters argue that the IGF-1 in milk is not absorbed into the body; however, the consumption of cow’s milk has been scientifically shown to increase the serum level of IGF-1 in humans by 10%. In contradiction of their own claims, the Dairy Council has even utilized a study confirming this increase in IGF-1 as a supporting document for bone health.
  • Higher levels of IGF-1 (insulin-like growth factor-1) in humans have been linked to a significantly increased risk of Prostate, Colon, Lung and Breast Cancer.
As if the direct effects of rBGH were not enough….
  • Cows treated with rBGH were found to have a 25% increased risk of acquiring an udder infection (mastitis). Other major side effects (as noted by the manufacturer of rBGH) include infertility, lameness, cystic ovaries, uterine disorders, digestive disorders, lacerations, and calluses of the knee
Cue the antibiotics!
  • An increase in infections results in an increase of antibiotic use, both legal and illegal.
  • Antibiotic residues in milk may cause allergic reactions in sensitive individuals, and may be an important factor in the growth of antibiotic resistant bacteria.
  • Testing for antibiotics is limited in its effectiveness. Mandatory screenings by milk processors are only for a few select antibiotics (while dozens of types are in use). Additional testing is randomized and on more of an “auditing” level.
  • Even for those batches, which pass inspection, low levels of antibiotic residues are typically permitted. The effects of these low levels, in addition to the potential antibiotic levels of untested milk, is largely unknown, but greatly feared.
  • In 2001, 6.7 million pounds of milk were dumped in Minnesota alone due to the detection of antibiotic residue. This was just from the 10% of loads randomly inspected on a quarterly review. One might either be shocked by the idea of how much “tainted” milk must have gone untested and continued on into our milk supply, or by the incredible amount of waste. Both the health and social implications of antibiotic use are of deep concern.

The 15 member countries of the European Union have banned the use of rBGH, as have Australia, New Zealand, and Canada. They have deemed rBGH as unsafe from both public health and veterinary perspectives. In 1999, Codex Alimentarius (the United Nations’ food safety organization), ruled in favor of the European moratorium on hormone treated milk products. So why on earth did the FDA approve rBGH, and why are dairy farmers in the United States, Mexico, and South Africa still routinely administering it? We as consumers are still waiting for that answer.

Use caution, dairy manufacturers within the United States are not required to disclose the use of rBGH on their labeling. Since the effects of the hormones in untreated cows are not fully understood, an excellent option is a dairy free or limited lifestyle. However, for those who choose to consume some milk products, reach for organic, raw, or at the very least those products specified as rBGH free.

Other Related Articles:


  1. “Dietary Changes Favorably Affect Bone Remodeling in Older Adults”; Journal of the American Dietetic Association 1999;99:1228–1233.
  2. “Insulin-like growth factors 1 and 2 in bovine colostrum. Sequences and biological activities compared with those of a potent truncated form.”; Biochem J. 1988 Apr 1;251(1):95-103 www.pubmed.org
  3. An rBGH Overview; Vermont’s Voice (a consumer advocacy organization).
  4. “Milk and the Cancer Connection” by Hans R. Larsen, MSc ChE; International Health News Issue 76, April 1998; Definition, BGH
  5. “MDA’s role in preventing antibiotic resistance” Minnesota Department of Agriculture

About Author

Alisa is the founder of GoDairyFree.org, Food Editor for Allergic Living magazine, and author of the best-selling dairy-free book, Go Dairy Free: The Guide and Cookbook for Milk Allergies, Lactose Intolerance, and Casein-Free Living, and the new cookbook, Eat Dairy Free: Your Essential Cookbook for Everyday Meals, Snacks, and Sweets. Alisa is also a professional recipe creator and product ambassador for the natural food industry.


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  2. I do not agree with the whole antibiotic misconception. There is NO ANTIBIOTIC RESIDUE IN MILK. MILK is tested multiple times before it comes to the cup on your table. The test used is called the snao test and is accurate to 6 parts per million. Each individual tank is tested at least once by the farmer, again by the milk truck driver (who also takes a sample to be tested later), then is tested (both the bull tank and the samples) before it is in the facility where it is tesed at least once more. If there is antibiotics found in a farmer’s milk, they are stripped of their producers license. Talk to a dairy farmer and see just how carful they are to ensure antibiotics are not in milk. Also, mastitis is caused by bacteria entering the teat (usually by manure) not by the synthetic hormone.

    • Hi Natalie, thank you so much for sharing your opinion. You are making a false claim of “no antibiotic residue”. In addition to what I cite above, I can pull up many other studies and tests that clearly state violations and the percentage of antibiotics they believe (FDA) make it into our milk supply. It’s a very small percentage but of a very large amount. Also, I did not say that synthetic hormones cause mastitis. Please read the study. They have seen a 25% increase in the rate of mastitis when synthetic hormones are used. I could not say way, but it may be due to decreased immunity / increased susceptibility.

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