Which Dairy Products Contain Hormones? Understanding Natural vs. Synthetic

October 5, 2025 •

3 min read

A 2023 survey indicated that more than one in five people were unaware that hormones are naturally present in milk. Understanding which dairy products contain hormones is key for making informed dietary choices, distinguishing between naturally occurring and potentially added hormones that can be a source of consumer concern.

Quick Summary

All dairy products contain natural hormones like estrogen, progesterone, and IGF-1, with levels influenced by the animal's reproductive cycle. Synthetic growth hormones (rBGH/rBST) are also used in some conventional dairy farming to increase milk output.

Key Points

All dairy contains hormones: All milk, regardless of farming method, contains naturally occurring hormones like estrogen and IGF-1 from the cow.
Fat content concentrates hormones: High-fat dairy products like butter and cream contain higher concentrations of fat-soluble hormones compared to low-fat milk or yogurt.
Pregnant cows have higher levels: Milk from pregnant cows, especially in the later stages, contains significantly higher levels of hormones such as estrogen and progesterone.
Organic milk prohibits synthetic hormones: USDA organic standards ban the use of synthetic growth hormones (rBGH/rBST), but it still contains natural hormones.
Synthetic hormones are still used conventionally: While many conventional brands are now rBGH-free, some still use it to boost milk production, which also elevates IGF-1 levels.
Digestion breaks down hormones: The human digestive system effectively breaks down most hormones, particularly protein-based ones, limiting their biological activity when consumed.

The Inevitable Presence of Natural Hormones

All dairy products, regardless of farming practices, contain naturally occurring hormones. These include estrogen, progesterone, and Insulin-like Growth Factor 1 (IGF-1), which are transferred from the cow's blood into the milk.

Estrogen and Progesterone: Levels of these sex steroid hormones are higher in milk from pregnant cows, which is common practice in the dairy industry.
Insulin-like Growth Factor 1 (IGF-1): This hormone, important for growth, is naturally in milk and can be influenced by factors like diet and supplemental hormones.
Other Natural Hormones: Milk also contains hormones like prolactin and glucocorticoids, which are generally broken down during human digestion.

The Impact of Farming on Hormone Levels

Farming practices can affect hormone levels, especially concerning synthetic growth hormones not permitted in all countries.

Synthetic Growth Hormones (rBGH/rBST)

Recombinant bovine growth hormone (rBGH), or rBST, is a synthetic hormone used in the U.S. to boost milk production, although banned in many other nations. It increases a cow's natural IGF-1 levels, potentially leading to slightly higher IGF-1 in milk, though this difference is considered insignificant by regulatory bodies like the FDA and WHO. The U.S. Food and Drug Administration offers more information on bovine somatotropin.

Organic vs. Conventional Dairy: The Key Difference

The main difference is that USDA certified organic dairy prohibits rBGH/rBST use. Both organic and conventional milk contain natural hormones. Many conventional producers voluntarily avoid rBGH and label their products as such.

Do All Dairy Products Contain the Same Amount of Hormones?

Hormone concentration can change during processing, particularly for fat-soluble hormones like progesterone and certain estrogens, which become more concentrated in higher-fat products.

Hormone Concentration in Common Dairy Products

Milk: Contains natural hormones with levels varying based on the cow.
Cream: Higher in fat-soluble hormones due to its fat content.
Butter: Has the most concentrated levels of fat-soluble hormones because it's nearly all milk fat.
Yogurt: Hormone content is similar to the milk used, with fermentation not significantly altering it.
Cheese: Hormone concentration depends on fat content; fattier cheeses may have higher levels of fat-soluble hormones.

Comparison Table: Organic vs. Conventional Dairy


Feature	Conventional Dairy	Organic Dairy
Synthetic Hormones (rBGH/rBST)	May be used	Prohibited
Naturally Occurring Hormones	Present	Present
Antibiotics	Used	Prohibited (with alternatives or removal from program)
Animal Welfare Standards	Variable	Requires outdoor access
Overall Hormone Level	Can be influenced by rBGH/rBST	Naturally occurring levels only

Are Hormones in Dairy Safe for Human Consumption? The Scientific Perspective

Health authorities generally consider dairy safe. The human digestive system effectively breaks down protein-based hormones like rBGH and largely breaks down steroid hormones like estrogen, limiting their activity when consumed.

Research into potential links between high dairy intake and hormone-related conditions is ongoing and not conclusive. Many factors influence health risks. Dairy's nutritional benefits (calcium, protein, vitamin D) are well-established. Choosing organic or limiting dairy is often based on personal preference, health concerns, and ethical views.

Conclusion

All dairy products naturally contain hormones, including estrogen, progesterone, and IGF-1, with levels influenced by the cow's reproductive stage. The main difference between organic and conventional dairy is the prohibition of synthetic hormones like rBGH/rBST in organic production. High-fat dairy products like butter and cream have higher concentrations of fat-soluble hormones. While health concerns exist, major health organizations generally consider milk from rBGH-treated cows safe, though some consumers prefer organic or rBST-free options for various reasons.

Frequently Asked Questions

Yes, organic dairy products naturally contain hormones because milk is a biological fluid produced by a cow's body. The key difference is that organic standards prohibit the use of synthetic growth hormones like rBGH/rBST, but they do not eliminate natural hormones.

rBGH (recombinant bovine growth hormone), also known as rBST, is a synthetic hormone used in some conventional dairy farming to increase milk production. Its use is banned in many countries but permitted in the US. The majority of milk sold in stores is now voluntarily labeled as rBST-free, and organic milk never contains it.

Major health organizations like the FDA have concluded that dairy from rBGH-treated cows is safe for human consumption. This is largely because protein-based hormones are broken down in the digestive system. The debate around potential long-term effects of slightly elevated hormone levels in milk is ongoing and not conclusive.

Butter has more hormones than milk because it is a concentrated fat product. Some hormones, such as progesterone and certain types of estrogen, are fat-soluble and become more concentrated when milk fat is separated during processing to make cream and butter.

The impact of dietary hormones on human hormonal balance is a topic of ongoing research and debate. While high dairy consumption has been studied in relation to conditions like hormone-related cancers, definitive evidence of a causal link to widespread hormonal imbalances is lacking.

Plant-based milk alternatives such as soy, almond, and oat milk do not contain animal hormones. However, some, like soy, contain phytoestrogens, which are plant-based compounds that can have a weak estrogenic effect on the body.

Pasteurization is a heat treatment that kills bacteria, but it does not effectively destroy or remove hormones from milk. While some protein-based hormones might be partially denatured, the overall hormone content is largely unaffected by pasteurization.