Last updated on: 10/13/2010 | Author:

Are There Any Safety or Nutritional Differences in Milk from Cows Supplemented with Growth Hormones Such as rBST and Milk from Cows Not Supplemented with Hormones?

General Reference (not clearly pro or con)

rbST Facts, a website dedicated to bovine growth hormone information, explained in the article “The Facts About rbST,” (accessed Mar. 22, 2007):

“rbST is known by many names. These include ‘bST,’ ‘bGH,’ ‘rbGH’ and ‘Posilac.’ The clinical name for the naturally occurring protein hormone produced in the pituitary glands of all cattle is ‘bovine somatotropin,’ denoted as ‘bST.’ Human beings have learned how to reproduce an exact copy of this substance by means of recombinant DNA technologies. This version of bST is called ‘recombinant bovine somatotropin’ or ‘rbST.’ These are the names scientists use to describe these substances.

All somatotropins – whether from cattle, dogs, monkeys or human beings – are growth hormones. bST and rbST are therefore sometimes referred to as ‘bovine growth hormone’ (bGH) and ‘recombinant bovine growth hormone’ (rbGH), respectively.

‘Posilac’ is a brand name, not a scientific title. It was trademarked by Monsanto Inc. to refer to the commercially available version of rbST that the company manufactures. Monsanto Inc. is the only company approved by the U.S. Food & Drug Administration (FDA) to manufacture and sell rbST within the United States…

rbST boosts milk production in the average cow by about 10 percent to 15 percent. Higher and lower increases are not unknown; rbST impacts different animals differently.”

Mar. 22, 2007

PRO (yes)


In IDFA v. Boggs, the United States Court of Appeals for the Sixth Circuit ruled in its Sep. 30, 2010 (3-0) decision overturning Ohio’s ban on milk labels such as “rBGH free” or “artificial hormone free”:

“[T]he use of rbST in milk production has been shown to elevate the levels of insulin-like growth factor 1 (IGF-1), a naturally-occurring hormone that in high levels is linked to several types of cancers, among other things. The amici [Center for Food Safety] also point to certain studies indicating that rbST use induces an unnatural period of milk production during a cow’s ‘negative energy phase.’ According to these studies, milk produced during this stage is considered to be low quality due to its increased fat content and its decreased level of proteins. The amici further note that milk from treated cows contains higher somatic cell counts, which makes the milk turn sour more quickly and is another indicator of poor milk quality. This evidence precludes us from agreeing with the district court’s conclusion that there is no compositional difference between the two types of milk.”

Sep. 30, 2010 - IDFA v. Boggs


Samuel S. Epstein, MD, Chairman of the Cancer Prevention Coalition, stated in the Aug. 29, 2006 press release titled “Hormonal Milk Poses Greater Risks Than Just Twinning,” to support his book What’s In Your Milk?:

“Hormonal milk contains up to ten-fold increased levels of the natural Insulin-like Growth Factor, known as IGF… Hormonal milk is very different than natural milk. Hormonal milk is often contaminated with pus cells, resulting from mastitis in cows due to hyperstimulation of milk production, and also with antibiotics used to treat the mastitis. Other abnormalities include increased fatty acids, which are incriminated in heart disease.

More serious are major risks of breast, colon, and prostate cancers due to increased IGF levels in hormonal milk. Evidence for this has been documented in about 50 scientific publications over the past three decades… A less well-recognized risk is evidence that IGF blocks natural, self-destructive, defense mechanisms against early submicroscopic cancers, technically known as apoptosis.”

Aug. 29, 2006


Martin T. Donohoe, MD, and Rick North, Science Advisor and Project Director, respectively, for the Oregon Physicians for Social Responsibility Campaign for Safe Food, report in their August 31, 2006 article “Errors in MSNBC Story on Organic Milk,” (available online) written in response to Karen Collins’ article “Organic Milk: Are the Benefits Worth the Cost?”:

“It is well known that rBGH increases levels of another growth hormone, IGF-1, which is identical in cows and humans. At elevated levels, IGF-1 is known to increase cancer rates in humans. Dale Bauman’s point that the body produces more IGF-1 than is taken in by dietary factors is accurate, as far as it goes. But he completely ignores the fact that even small additional amounts of hormones can have significant effects on human health. Moreover, there is much that is still unknown about IGF-1, especially long-term effects of drinking large quantities of milk at a young age…

Most of the industrialized nations of the world, including Canada, Australia, New Zealand, Japan and all 25 nations of the European Union, have disallowed the use of rBGH, based primarily on human and animal health concerns. The Codex Alimentarius, the U.N.’s main food safety body, has concluded there is NO consensus that rBGH is safe for human consumption.”

Aug. 31, 2006


The Physicians Committee for Responsible Medicine (PCRM), a health advocacy organization, explained in its article “What’s Wrong with Dairy Products?,” published on their website (accessed Mar. 26, 2007):

“Synthetic hormones such as recombinant bovine growth hormone (rBGH) are commonly used in dairy cows to increase the production of milk. Because the cows are producing quantities of milk nature never intended, the end result is mastitis, or inflammation of the mammary glands. The treatment requires the use of antibiotics, and traces of these and hormones have been found in samples of milk and other dairy products.”

Mar. 26, 2007

CON (no)


Monsanto, the developer of rBST (Posilac®), stated in its July 16, 2009 publication “Milk Labeling – Is Monsanto Opposed to Truth in Labeling?,” available at the Monsanto website:

“Monsanto’s rBST product, Posilac, is a supplement of the naturally occurring cow hormone BST, that when administered to cows allows them to produce more milk. Many dairy farmers use Posilac because they can produce more milk with fewer cows. The milk from treated cows is identical to milk produced by cows that are not treated. There is no laboratory anywhere in the world that can tell the difference between milk from a cow that has been treated with Posilac and milk from one that hasn’t been treated. Milk from treated cows is just as safe as milk from untreated cows. This has been affirmed by the U.S. Food and Drug Administration, World Health Organization, American Medical Association, American Dietetic Association and regulatory agencies in 30 countries.”

July 16, 2009


The US Food and Drug Administration’s (FDA) Feb. 14, 1994 “Interim Guidance on the Voluntary Labeling of Milk and Milk Products From Cows That Have Not Been Treated With Recombinant Bovine Somatotropin,” published in the Federal Register, stated:

“FDA is concerned that the term ‘rbST-free’ may imply a compositional difference between milk from treated and untreated cows rather than a difference in the way the milk is produced… Such unqualified statements may imply that milk from untreated cows is safer or of higher quality than milk from treated cows. Such an implication would be false and misleading.

There is currently no way to differentiate analytically between naturally occurring bST and recombinant bST in milk, nor are there any measurable compositional differences between milk from cows that receive supplemental bST and milk from cows that do not.”

Feb. 14, 1994 - Interim Guidance on the Voluntary Labeling of Milk and Milk Products From Cows That Have Not Been Treated With Recombinant Bovine Somatotropin


Karen Collins, RD, CDN, a registered dietician, wrote in her Aug. 25, 2006 article “Organic Milk: Are the Benefits Worth the Cost?,” posted on the MSNBC website:

“[Some people] express concern that growth hormones in milk could raise the risk of hormone-related cancers, or lead to higher levels of an insulin-like growth factor (IGF-1) linked with cancer. But BGH [bovine growth hormone] is a protein hormone, which means that if any does appear in milk, enzymes and acid in our digestive tract destroy it…

If IGF-1 is slightly higher in milk from BGH-treated cows, it represents a tiny fraction of the IGF we all produce each day. [Dale] Bauman reports that we would have to drink 95 quarts of milk to equal the IGF-1 we make daily in our saliva and other digestive tract secretions.”

Aug. 25, 2006


Terry D. Etherton, PhD, and Dale E. Bauman, PhD, reported in their July 1998 paper “Biology of Somatotropin in Growth and Lactation of Domestic Animals,” published in Physiological Reviews:

“The gross composition of milk (fat, protein, and lactose) is not altered by [supplemental] treatment with bST… Microconstituents of milk are also unchanged. For example, milk from bST-treated cows does not differ in vitamin content or in concentrations of nutritionally important mineral elements. Milk also contains many hormones and growth factors; two that have received substantial attention are ST [somatotropin] and IGF-1 [insulin-like growth factor-1]. At the bST doses that enhance milk yield, the concentration of bST in milk is unchanged…

In the case of IGF-1… it became evident that milk IGF-1 varied widely between cows and was affected by many factors (e.g., herd, stage of lactation, environment), and use of bST has minimal, if any, impact on the milk concentration of IGF-1. Overall, studies of the macro- and microcomponents of milk indicate that composition is unaltered by [supplemental] use of bST.”

July 1998