Does Raw Milk Have Growth Hormones?

December 24, 2025 •

4 min read

All milk, including raw milk, contains naturally occurring hormones, a biological reality for any lactating mammal. This fact, however, is often conflated with the use of synthetic bovine growth hormones (rBST), creating confusion for consumers who ask, "Does raw milk have growth hormones?"

Quick Summary

Raw milk naturally contains minute, species-specific growth hormones and other peptides, which are functionally inactive in humans after digestion. The key distinction is between these natural hormones and the synthetic version, rBST, which is prohibited in organic milk production.

Key Points

Natural Hormones Exist: All raw milk contains minute, naturally occurring growth hormones like bovine somatotropin (bST), but these are inactive in humans.
Synthetic Hormones (rBST) are Different: The synthetic growth hormone rBST is prohibited in organic milk production and its use is a separate issue from natural hormones.
Digestive Inactivation: The human digestive system breaks down any residual bovine hormones, rendering them inactive and harmless.
Risks are Bacterial, Not Hormonal: The main health concern with raw milk is not hormones but the significant risk of contamination from dangerous bacteria like E. coli and Salmonella.
Pasteurization Kills Bacteria: The pasteurization process is highly effective at killing harmful pathogens and is the primary reason why pasteurized milk is considered a safer choice.
Vulnerable Populations at Higher Risk: Children, the elderly, and pregnant women face a greater risk of severe illness from consuming contaminated raw milk.

Understanding Hormones in Milk

To clarify the question of whether raw milk has growth hormones, it's crucial to distinguish between naturally occurring hormones and synthetic ones. Hormones are simply chemical messengers present in all living organisms, including plants and animals. Therefore, there is no such thing as 'hormone-free' milk or food.

The Role of Natural Bovine Growth Hormones

Cows, like humans, produce a natural growth hormone called bovine somatotropin (bST). This hormone is essential for the cow's growth, development, and lactation. A minuscule amount of this hormone transfers into the cow's milk during lactation. However, there are two key reasons this poses no concern for human consumption:

Species-Specific Activity: The bovine growth hormone is biologically active only in cows and other similar species. In humans, it is inactive.
Digestive Breakdown: As a protein, bST is broken down into its constituent amino acids during the human digestive process, rendering it inactive and eliminating any potential effect.

The Controversy Over Synthetic Hormones (rBST)

Some conventional dairy farmers, particularly in the United States, have historically used a synthetic version of bST called recombinant bovine somatotropin (rBST) to increase milk production. The use of rBST is a separate issue from the presence of natural hormones.

It is important to understand:

Organic Milk Standards: USDA organic regulations prohibit the use of rBST in the production of organic milk.
Labeling: Many dairy products, including both conventional and organic options, are now labeled as being "from cows not treated with rBST" or "rBST-free".
FDA Position: The FDA has long maintained that there is no significant difference between milk from rBST-treated and non-rBST-treated cows.

Growth Factors in Raw Milk

Beyond growth hormones, raw milk also contains other biologically active substances, such as insulin-like growth factor 1 (IGF-1). Advocates of raw milk often point to these factors as beneficial, but the scientific community offers a more nuanced view.

Here are some considerations regarding IGF-1:

The concentration of IGF-1 in cow's milk is significantly lower than the amount naturally produced by the human body.
IGF-1 levels in human saliva are comparable to those found in milk, suggesting that dietary intake of milk-derived IGF-1 has no significant impact.
Studies have shown that a variety of other foods, particularly those high in protein, can also cause a temporary, small rise in circulating IGF-1 levels.

Raw vs. Pasteurized Milk: A Comparative Look

Choosing between raw and pasteurized milk involves weighing perceived benefits against potential risks. While proponents of raw milk focus on its “natural” state, health experts emphasize the importance of pasteurization for food safety.


Feature	Raw Milk	Pasteurized Milk
Hormones (bST)	Contains minute, natural bovine somatotropin.	Contains trace amounts of natural bST, most of which is destroyed by heat treatment.
Synthetic Hormones (rBST)	Typically not used by farms selling raw milk directly; often labeled 'rBST-free'.	May contain trace amounts of rBST if cows were treated, but most brands are labeled 'rBST-free'.
Pathogenic Bacteria	High potential for harmful bacteria (e.g., E. coli, Salmonella, Listeria) due to lack of heat treatment.	Heats milk to kill harmful pathogens, significantly reducing the risk of foodborne illness.
Enzymes & Probiotics	Contains a natural profile of enzymes and beneficial bacteria, which are destroyed during pasteurization.	Lacks the raw enzymes and beneficial bacteria destroyed by heat processing.
Lactose Intolerance	Claimed to be more digestible for some due to lactase content, but scientific evidence is lacking.	Contains the same concentration of lactose as raw milk, though often blamed for intolerance.
Nutritional Value	Advocates claim superior nutritional content, but studies show minimal nutritional difference, with some heat-sensitive vitamins only slightly affected.	Retains nearly all nutritional value, including protein, calcium, and fat-soluble vitamins.
Safety Warning	Recommended against for high-risk individuals, including pregnant women, children, and the immunocompromised.	Widely considered safe for all populations due to pasteurization.

The Risks of Raw Milk Consumption

The primary concern with raw milk is not growth hormones but the serious risk of bacterial contamination from harmful pathogens. Public health authorities widely recommend against consuming raw milk.

Bacterial Contamination: Raw milk can become contaminated with dangerous bacteria such as Campylobacter, E. coli, Listeria, and Salmonella during milking, handling, or storage.
Outbreaks and Illness: The Centers for Disease Control and Prevention (CDC) have consistently linked raw milk consumption to outbreaks of foodborne illness. Vulnerable populations, including young children, the elderly, and pregnant women, face the highest risk of severe illness.
No Guarantees: Even milk sourced from healthy, well-managed farms and subject to regular testing cannot be guaranteed to be 100% free of all harmful bacteria. Occasional testing may miss low-level contamination.

Conclusion

In conclusion, the answer to "Does raw milk have growth hormones?" is yes, but the context is key. Raw milk contains a minuscule, naturally occurring amount of bovine growth hormone, which is species-specific and inactive in humans. The more relevant concern for consumers is the potential presence of synthetic growth hormones (rBST), which are prohibited in organic milk production and avoided by many conventional farms. Crucially, the biggest health risk associated with raw milk is not hormones but the very real and significant danger of bacterial contamination, which pasteurization effectively eliminates.

For those seeking the safest option, health authorities widely recommend pasteurized dairy. Individuals who choose to consume raw milk, particularly vulnerable groups, do so at their own risk of contracting serious foodborne illnesses.

Additional Resources

U.S. Food and Drug Administration (FDA) on Raw Milk: https://www.fda.gov/food/buy-store-serve-safe-food/raw-milk-misconceptions-and-danger-raw-milk-consumption

Sources

Baldwin Brook Farm. (n.d.). Is the milk free of hormones? https://baldwinbrookfarm.com/faq/is-the-milk-free-of-hormones/
Healthline. (2023, May 15). Drinking Raw Milk: Benefits and Dangers. https://www.healthline.com/nutrition/drinking-raw-milk
GonnaNeedMilk. (n.d.). The Facts About Hormones In Milk. https://gonnaneedmilk.com/articles/facts-about-hormones-milk/
UCLA Health. (2024, January 31). Dangers of raw milk arise from bacteria. https://www.uclahealth.org/news/article/dangers-raw-milk-arise-bacteria

Frequently Asked Questions

No, hormones are not added to milk, raw or otherwise. The growth hormones found in raw milk are naturally produced by the cow itself and are not supplemented, especially in organic production where the synthetic hormone rBST is prohibited.

No, the bovine growth hormone found naturally in raw milk is species-specific and does not have any biological effect on humans. The human body also breaks down these protein-based hormones during digestion.

Raw milk contains a natural, minute amount of bovine growth hormone, a majority of which is destroyed or inactivated during the heat treatment of pasteurization. However, the difference is negligible in terms of human health impact.

Natural bovine somatotropin (bST) is a hormone produced naturally by cows. Recombinant bovine somatotropin (rBST) is a synthetic version sometimes used by conventional farmers to increase milk yield. The use of rBST is prohibited in organic dairy farming.

No, the amount of IGF-1 in cow's milk is far lower than what the human body produces on its own, and dietary intake from milk has no significant biological effect on humans. Many other foods, particularly those high in protein, also naturally affect your body's IGF-1 production.

The primary danger of raw milk is not from hormones but from the potential presence of harmful bacteria like E. coli, Salmonella, and Listeria, which can cause serious foodborne illnesses. Pasteurization is a heating process specifically designed to eliminate these pathogens.

No, no food is truly "hormone-free" because all plants and animals naturally produce hormones. However, you can buy milk labeled as being from cows not treated with the synthetic growth hormone rBST, including all organic milk.