You rarely think about food safety when you shop and cook. Yet, activists remain concerned about the possibility of foodborne disease. Farmers have, for many years, given livestock growth hormones to increase their yield. These hormones and related residues may eventually end up in your dairy and meat products, resulting in positive and negative effects on your body.
Background on Natural Growth Hormone
A 2018 paper in Pediatric Endocrinology Reviews tells about the discovery of somatotropin, a chain of amino acids known as human growth hormone or hGH. Researchers have been trying to stimulate human growth with this hormone since 1932, but it actually plays many roles in your body.
Doctors originally used pituitary gland extracts from human cadavers to encourage growth in hGH-deficient children. When these extracts appeared unsafe, chemists created a form called recombinant human growth hormone, or rhGH. Athletes have abused this form of growth hormone for performance enhancement.
Understanding Artificial Growth Hormone
There are also legal ways around the regulations. For example, the FDA has approved genetically modified salmon. These fish have high levels of growth hormone and show an enhanced musculature.
Growth Hormone Transfer
Changing the growth hormone levels of livestock and fish affects not only the animals, but the bodies of those who consume these products. A diet rich in dairy products — especially milk — increases your hormone levels. The finding suggests that some transfer and some absorption of milk-related hormones occurs when you drink milk. These changes should cause concern because of the potential for endocrine disruption.
Positive Effects of Growth Hormone
It still isn't known whether these positive effects would occur in children and adults with normal levels of growth hormone. Such use is associated with side effects and brings up ethical concerns.
Negative Effects of Growth Hormone
Insulin-Like Growth Factor
Growth hormone triggers insulin-like growth factor release in the liver. The two hormones have a direct relationship. That is, the more growth hormone you ingest, the greater your levels of insulin-like growth factor. So cattle given potent rBGH injections have abundant insulin-like growth factor.
The primary role of this hormone is promoting cell growth and preventing cell death. Like growth hormone, injecting insulin-like growth factor causes anabolic effects such as muscle enhancement and bone growth. This has resulted in athletes abusing it to gain a competitive edge.
The stomach may not fully absorb insulin-like growth factor, according to a 2017 paper in Best Practice and Research, so ingesting milk may increase insulin-like growth factor through another mechanism. Growth hormone also increases casein. So, it and other branched amino acids may explain the large increases in insulin-like growth factor seen in milk after cattle receive rBGH injections.
Know Your Cancer Risk
According to a 2015 report in Genes and Diseases, a strong relationship exists between insulin-like growth factor and cancer. Higher insulin-like growth factor levels correlate well with greater cancer risk. For example, people with the highest levels have a 40 percent greater risk of getting prostate cancer. A similar relationship exists between insulin-like growth factor and other types of cancer.
Know Your Drug Resistance Risk
Cancer treatment has plateaued in recent years. Tumors resist standard treatments in many cases. Insulin-like growth factor may play a role in this resistance, according to a 2016 paper in the International Journal of Molecular Sciences.
A 2016 report in Oncotarget illustrates this problem in breast cancer patients. Tamoxifen remains the primary drug used to help treat breast cancer. But many patients develop a resistance to this useful drug, increasing their risk of not surviving treatment.
Patients showing drug resistance develop a sensitivity to insulin-like growth factor. In these people, the target cells for this hormone become more porous. That change gives the high levels of insulin-like growth factor present in breast cancer patients even more targets to attack. This vulnerability causes the cancer to grow and spread.
Be Aware of Your Exposure
Animals given artificial growth hormone experience more problems than untreated animals. In cows, these problems include udder swelling, udder infection, infertility and lameness. Genetically altered salmon have unusually large heads and have difficulty breathing.
Further exposure to antibiotics through animals can result from farmers typically giving antibiotics to injured animals. These can leach into dairy and meat products that are purchased and consumed. Such exposure may explain the antibiotic resistance now seen in many medical conditions.
Respect the Animals
Injecting animals with growth hormones also brings up animal welfare issues. Nearly 90 percent of feedlot cattle receive some form of injection, according to a 2017 paper presented at the
This increased, heavy use of hormones alters daily interactions between farm animals. A 2015 report in Applied Animal Behaviour Science looked at the behavior of steers given growth-promoting drugs. Compared to controls, implanted animals engaged in more aggressive actions like pushing each other. The enhanced growth also seemed to affect the animals' ability to stay upright. Implanted animals spent 31 percent more of their time lying around.
Respect the Environment
The authors of a 2017 report in the Proceedings of the Nutrition Society suggest that current levels of dairy and meat production may be unsustainable. The Earth appears burdened by factory farming and its consequences — antibiotic resistance, climate change and crowding. A shift away from growth hormone injections and a move toward free-range farming could ease this burden.
- Pediatric Endocrinology Reviews: Growth Hormone Discovery and Structure
- Best Practice and Research – Clinical Endocrinology and Metabolism: Functional Analysis of the IGF-System in Milk
- Genes and Diseases: Insulin-Like Growth Factor (IGF) Signaling in Tumorigenesis and the Development of Cancer Drug Resistance
- International Journal of Molecular Sciences: Emerging Role of miRNAs in the Drug Resistance of Gastric Cancer
- Oncotarget: Deregulation of IGF-Binding Proteins -2 and -5 Contributes to the Development of Endocrine Resistant Breast Cancer In Vitro
- Southern Agricultural Economics Association: Impact of Hormone Use Perception on Consumer Meat Preference
- Applied Animal Behaviour Science: Effects of Growth-Promoting Technology on Feedlot Cattle Behavior in the 21 Days Before Slaughter
- Seton Hall Univesity: Animal Welfare Is a Major Public Health Concern
- Proceedings of the Nutrition Society: Improving the Sustainability of Global Meat and Milk Production