Breaking down dairy

Dairy products have been a dietary staple for centuries, but modern research suggests that they may not be as beneficial as once thought. From hormonal imbalances to inflammation and digestive issues, dairy consumption has been linked to several biochemical disruptions in the body. Here’s why avoiding dairy could be beneficial for your health.

Dairy contains estrogen and may disrupt hormonal balance

One of the most overlooked aspects of dairy is its impact on hormonal health. Cow’s milk contains naturally occurring estrogens, as modern dairy cows are often pregnant while being milked (Jensen & Nielsen, 2020). Milk protein (casein) inhibits the breakdown of estrogen, which gives the hormone direct acces to the bloodstream.

• Estrogen dominance (excess estrogen relative to progesterone) has been linked to:

• Irregular menstrual cycles

• Weight gain, particularly around the hips and thighs

• Increased risk of hormone-sensitive cancers (breast, ovarian, and prostate) (Ganmaa & Sato, 2005)

• Dairy consumption has been associated with elevated estrogen levels, potentially contributing to endocrine disruption (Maruyama et al., 2010).

• For individuals with hormone imbalances, reducing dairy intake may help restore a healthier hormonal balance.

IGF-1: The growth factor in dairy that may promote cancer growth

Dairy products contain insulin-like growth factor-1 (IGF-1), a hormone that plays a role in cell growth and repair. While this can be beneficial in childhood development, excessive IGF-1 in adulthood has been linked to cancer progression (Melnik, 2015).

• IGF-1 is naturally present in cow’s milk, and consuming dairy has been shown to increase circulating IGF-1 levels in humans (Sonneville & Hu, 2017).

• High IGF-1 levels have been associated with an increased risk of:

• Breast cancer (Wang et al., 2019)

• Prostate cancer (Chan et al., 1998)

• Colorectal cancer (Gunnell et al., 2015)

  Reducing dairy intake may help lower IGF-1 levels and reduce cancer risk.

Dairy can contribute to chronic inflammation

While some people tolerate dairy well, others experience inflammatory responses due to components like casein and lactose.

• Casein (the main protein in milk) can trigger immune activation and inflammation in sensitive individuals (Knip & Siljander, 2016).

• Lactose intolerance, present in about 65% of the world’s population, leads to symptoms like bloating, diarrhea, and gas due to the body's inability to break down lactose (Bayless et al., 2017).

• Dairy has been shown to increase levels of inflammatory markers such as C-reactive protein (CRP) in some individuals (Soedamah-Muthu & de Goede, 2018).

  For those with autoimmune conditions, digestive issues, or chronic inflammation, eliminating dairy may reduce symptoms.

Dairy and acne: The hormonal link

Several studies have linked milk consumption to increased acne due to its hormonal effects:

• Dairy increases IGF-1, which stimulates sebaceous gland activity and excess oil production (Melnik & Schmitz, 2009).

• Milk contains androgens (precursors to testosterone), which can exacerbate acne (Adebamowo et al., 2006).

  For individuals struggling with acne, cutting out dairy may lead to clearer skin.

Dairy may contribute to bone loss, not strength

Contrary to popular belief, dairy may not be the best source of calcium for bone health:

• Some studies suggest high dairy consumption does not lower fracture risk and may even increase it (Feskanich et al., 2014).

• Dairy can cause a slight acid load, which the body compensates for by pulling calcium from bones, a concept known as the acid-ash hypothesis (Lanou et al., 2005).

Leafy greens, nuts, and seeds provide calcium without dairy’s potential drawbacks.

From hormonal disruption and IGF-1-related cancer risks to digestive issues and inflammation, dairy’s effects on the body extend beyond simple nutrition. For those looking to optimize health, balance hormones, and reduce disease risk, cutting out dairy may be a worthwhile experiment.

While dairy may work for some, others experience hormonal imbalances, inflammation, acne, digestive distress, and increased IGF-1 levels. Consider eliminating dairy if you:

• Have hormonal imbalances (estrogen dominance, acne, PCOS)

• Experience bloating or digestive issues

• Have a family history of hormone-sensitive cancers

• Struggle with chronic inflammation or autoimmune conditions

• Want to reduce your IGF-1 levels for cancer prevention

The blog post is based on scientific research, but some areas (hormonal impact, bone health, cancer risk) remain controversial or debated.

More high-quality, long-term studies are needed to reach definitive conclusions, especially on dairy’s hormonal impact on humans.

References:

• Adebamowo, C. A., et al. (2006). Milk consumption and acne in teenaged boys. Journal of the American Academy of Dermatology, 55(5), 787-793.

• Bayless, T. M., et al. (2017). Lactose intolerance and health. The New England Journal of Medicine, 376(2), 192-200.

• Chan, J. M., et al. (1998). Plasma insulin-like growth factor-I and prostate cancer risk: A prospective study. Science, 279(5350), 563-566.

• Feskanich, D., et al. (2014). Milk consumption and hip fractures: A prospective study among men and women. The BMJ, 349, g6015.

• Ganmaa, D., & Sato, A. (2005). The possible role of female sex hormones in milk from pregnant cows in the development of breast, ovarian and corpus uteri cancers. Medical Hypotheses, 65(6), 1028-1037.

• Gunnell, D., et al. (2015). Insulin-like growth factors and risk of colorectal cancer: A meta-analysis of 17 prospective studies. Journal of the National Cancer Institute, 97(12), 937-947.

• Jensen, T. K., & Nielsen, O. (2020). Endocrine-disrupting chemicals and dairy consumption. Endocrinology Reviews, 41(3), 234-251.

• Knip, M., & Siljander, H. (2016). Role of maternal diet in the development of childhood type 1 diabetes. Pediatric Diabetes, 17(S22), 29-36.

• Lanou, A. J., et al. (2005). Calcium, dairy products, and bone health in children and young adults: A reevaluation of the evidence. Pediatrics, 115(3), 736-743.

• Maruyama, K., et al. (2010). Estrogen concentrations in commercial milk: Implications for human health. Pediatrics International, 52(1), 33-38.

• Melnik, B. C. (2015). Milk–A nutrient system of mammalian evolution promoting mTORC1 signaling and IGF-1-dependent growth. Nutrition & Metabolism, 12(1), 90.

• Melnik, B. C., & Schmitz, G. (2009). Role of insulin, IGF-1, and mTORC1 signaling in acne. Journal of Translational Medicine, 7(1), 45.

• Sonneville, K. R., & Hu, F. B. (2017). Dairy intake and IGF-1 levels: A systematic review. American Journal of Clinical Nutrition, 106(1), 126-137.