Is There Growth Hormone in Organic Milk? A Complete Guide

January 7, 2026 •

2 min read

According to a 2019 study published in Public Health Nutrition, conventional milk contained bovine growth hormone (bGH) levels 20 times higher than organic milk. This significant difference addresses a common consumer concern and provides a clear starting point for the question: Is there growth hormone in organic milk?

Quick Summary

All milk naturally contains some bovine growth hormone, but USDA organic rules prohibit the use of synthetic versions like rBGH. The notable disparity in hormone levels between organic and conventional milk directly stems from these production differences.

Key Points

Natural vs. Synthetic Hormones: All milk contains natural bovine growth hormones (bGH), but organic milk comes from cows not treated with synthetic recombinant bovine growth hormone (rBGH/rBST).
USDA Organic Prohibition: The USDA organic certification prohibits the use of artificial growth hormones in dairy production.
Lower Hormone Levels: Studies show organic milk contains significantly lower levels of bovine growth hormone compared to conventional milk, reflecting the absence of synthetic hormones.
Animal Welfare: The prohibition of rBGH in organic farming avoids potential health complications for cows, such as an increased risk of mastitis.
Labeling Matters: While conventional milk may be labeled 'rBST-free,' the organic seal provides the most comprehensive assurance against synthetic growth hormones, antibiotics, and pesticides.
Informed Choice: For consumers prioritizing the absence of synthetic growth hormones, pesticides, and antibiotics, organic milk is the reliable choice, guided by the USDA seal.

The Core Difference: Natural vs. Synthetic Hormones

All milk contains natural bovine somatotropin (bST), a growth hormone found in cows. However, some conventional dairy farmers use recombinant bovine somatotropin (rBST), a synthetic version of bST, to increase milk production. This synthetic hormone is the primary concern for many consumers.

The Role of USDA Organic Certification

The USDA organic certification strictly prohibits the use of synthetic growth hormones like rBST/rBGH in dairy cows. This is a fundamental aspect of organic standards, ensuring that organic milk comes from cows not treated with these artificial hormones.

Comparing Hormone Levels in Organic vs. Conventional Milk

Research, such as a 2019 study by Emory University and The Organic Center, indicates that conventional milk has significantly higher levels of bovine growth hormone compared to organic milk. The study suggests these elevated levels in conventional milk are linked to the use of synthetic hormones, while levels in organic milk reflect natural biological processes.

Health and Animal Welfare Considerations

Concerns about rBGH use include potential animal welfare issues, such as increased risk of mastitis in cows, which can lead to higher antibiotic use in conventional farming. Organic farming prohibits antibiotics. While the FDA considers rBGH-treated milk safe for humans as bovine hormones are broken down during digestion, debates persist about the potential impact of increased levels of insulin-like growth factor 1 (IGF-1) associated with rBGH use. Organic milk consistently shows lower IGF-1 levels.

Navigating Milk Labels

Labels like "rBST-free" or "No artificial hormones" on conventional milk mean the cows weren't treated with synthetic hormones, but this doesn't equate to organic certification. The USDA organic label guarantees no synthetic hormones, along with other standards like organic feed, pasture access, and no antibiotics. For comprehensive avoidance of synthetic additives, the USDA organic seal is the most reliable indicator. More information can be found on the USDA Organic Program website.

Conventional vs. Organic Dairy: A Comparison


Feature	Conventional Dairy	Organic Dairy
Synthetic Growth Hormones (rBGH/rBST)	Permitted by FDA in the U.S.; used by some farms.	Strictly prohibited.
Natural Bovine Growth Hormone (bGH)	Present in trace amounts, potentially higher with synthetic hormone use.	Present in trace amounts consistent with natural cycle.
Antibiotic Use	Allowed for treatment; milk withheld.	Prohibited; animal loses organic status if treated.
Feed	May contain GMOs, pesticides, conventional ingredients.	Must be 100% organic, non-GMO, no synthetic pesticides.
Pasture Access	Not required.	Requires year-round outdoor access and grazing.

Conclusion

While natural growth hormones are present in all milk, certified organic milk is produced without synthetic growth hormones like rBGH or rBST due to USDA standards. Research confirms organic milk has significantly lower total growth hormone levels than conventional milk. Choosing organic milk is a way for consumers to avoid synthetic hormones and support practices aligned with organic standards for animal welfare and production.

Frequently Asked Questions

Yes, all milk, whether organic or conventional, contains naturally occurring bovine growth hormone (bGH). This is a natural hormone produced by cows to regulate growth and development.

bGH (bovine growth hormone) is the naturally occurring hormone in cows. rBGH (recombinant bovine growth hormone), also known as rBST, is a synthetic, lab-made version of bGH that is sometimes injected into conventional dairy cows to boost milk production.

No, organic milk does not contain artificial or synthetic hormones. The USDA organic standard prohibits farmers from treating cows with rBGH, the synthetic growth hormone.

No, rBGH-free milk is not necessarily organic. While the label indicates no synthetic growth hormones were used, the milk does not have to meet other strict organic standards for feed, pasture access, or antibiotic use.

Yes, studies have shown that organic milk contains significantly lower levels of total growth hormone compared to conventional milk, reflecting the absence of synthetic hormone use.

According to the FDA, the natural bGH in all milk is species-specific and broken down during human digestion, so it is inactive. The debate over health impacts related to rBGH and associated higher IGF-1 levels is ongoing, though the FDA deems it safe.

Some conventional dairy farmers may use synthetic rBGH to increase a cow's milk output and improve farm economics. However, consumer demand has led many conventional farms to voluntarily stop using it.