Estrogen & Other Sex Hormones Within Food & Body
Disclaimer: This article is for educational and informational purposes only. While detailed, the article provided is not inclusive of all information on the subject. It is not intended to treat or cure any ailment, condition, or disease. The link to the full journal article and other sources are listed below.
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Hormone Basics
Hormones are the body’s chemical messengers that travel through the bloodstream and bind to receptors to produce a variety of effects relating to growth, mood, development, metabolism, and more. Hormones can also be considered local (producing effects on neighboring cells) and not enter the bloodstream.¹ They are not only found within humans but animals and plants. In mammals, they can be categorized into water-soluble and lipid-soluble hormones. Hormones found in the body include insulin, glucagon, melatonin, serotonin, histamine, gastrin, calcitonin, epinephrine, norepinephrine, etc. This article focuses on sex hormones (estrogen, progesterone, testosterone, etc) as it relates to food production and potential health effects.
Functions of Sex Hormones in the Body
Hormones play vital roles within the body. Sex hormones, such as estrogen, progesterone, and testosterone, are responsible for the growth and development of reproductive systems. Estrogen and progesterone regulate the menstrual cycle, pregnancy, and secondary sex characteristics like breast growth.¹ Testosterone regulates sperm production and secondary sex characteristics such as voice deepening.¹ DHEA is a precursor for estrogen, progesterone, and testosterone.
Sex hormones affect other systems within the body other than reproductive organs. For example, estrogen binds to nuclear receptors, interacts with hormones, and stimulates skin and tissue growth and division.² Estrogen stimulates vasodilation of arteries found in the brain and heart by producing nitrous oxide.² Estrogen prevents platelet aggregation and vasoconstriction while promoting angiogenesis (formation of new blood vessels); it is credited for being heart-protective.²
Blood pressure and volume are also controlled by estrogen receptor genes to a certain extent.² Lower triglyceride levels and synthesis of HDL cholesterol are notable with estrogen as well.² Other than vasculature effects, estrogen is noted to affect bone density with post-menopausal women having a higher incidence of osteoporosis related to the lack of estrogen.² This is likely related to estrogen promoting the increase of osteoblasts (cells that build bone) and the decrease of osteoclasts (cell that breaks down bone).² The brain is also impacted by estrogen through the regulation of neuroplastic processes and is considered neuroprotective.²
Progesterone, along with estrogen, promotes skin regeneration through the synthesis of keratinocytes and the prevention of collagen breakdown.² Progesterone also stimulates the formation of neurosteroids important for the brain which can impact behavior and mood.² Testosterone stimulates lipolysis (breakdown of fat) and muscle growth. This results in a faster metabolism and higher resting metabolic rate. Also, testosterone stimulates erythropoietin, enhances iron absorption, and increases protein when bound to receptors within muscle.²
Sex Hormones Used in Food Production
Oftentimes, hormones are given to animals to increase meat or milk production - these are termed exogenous (not produced within the body or organism) hormones.³ For example, the United States Food and Drug Administration (FDA) approves the use of natural and synthetic forms of sex hormones estrogen, progesterone, and testosterone in beef cattle and sheep for growth purposes.⁴ Steroid hormone implants are not given to pigs, poultry, veal calves, and dairy cows for growth purposes; however, bovine somatotropin (often in the form of recombinant bovine somatotropin - rbST) is given to dairy cows to increase milk production.⁴ The FDA is responsible for ensuring the safety and efficiency of medication for animals, humans, and the environment alike.
Phytoestrogens Found within Food
Hormones produced within the organism are termed endogenous hormones.³ Animals, like humans, produce several hormones in the body that serve similar functions. Unlike mammals, plants produce structurally and functionally different hormones. However, some hormones found in plants are similar to certain animal hormones. Plant compounds such as isoflavones, lignans, coumestans, and certain phytoalexins are termed phytoestrogens because they exhibit estrogen-like hormone functions.³ Within plants, phytoestrogen serves to defend and develop their structures. Within humans, phytoestrogens can bind to estrogen receptors and either produce estrogen effects or anti-estrogen effects.³ However, it is important to note that the binding affinity is significantly less than 17 B-estradiol known as E2 (the most potent ligand that binds to estrogen receptors [ERS] in humans).³ Phytoestrogens can be found in cereals and breads, fruits, vegetables, legumes (especially soy), and wheat.³
While endogenous hormones are more bioactive and potent than hormones ingested within the diet, studies have found various functions relating to phytoestrogen.³ Effects of phytoestrogens are mixed - some observational studies show that soy isoflavones lower heart and fracture risks, reduce risks of cancer, and lower cholesterol.³ Other observational studies have shown both early and later puberty ages and both a presence and absence of male feminization related to soy isoflavones.³ Studies at this time are limited and require further research for correlations and effects of phytohormones.
Sex Hormone Amounts in Food
Hormones are found in foods in varying amounts even in the same products. It is dependent on the development, environment, and processing of the crops and animals.³ Also, the amount of hormones found in food is significantly lower than those produced within the body.³ Once ingested, the bioavailability of hormones found within food is highly dependent on the formation of bioactive forms and the body’s environment. In general, estrogen is higher in eggs compared to other foods, and higher progesterone levels are found in full-fat dairy foods, milk, and egg yolks compared to low-fat or fat-free foods.³ The amounts presented below are highly variable but are to be used for informational purposes only.
Daily Hormone intake based on 2,000 kcals diet per food group
Information gathered from Palacios et al.
Hormone Content of Selected Foods
Information gathered from Palacios et al.
Conclusion
Chemical messengers known as hormones are produced within the body and can be supplied externally. Both humans and animals produce hormones such as estrogen, testosterone, progesterone, and DHEA. They have several functions that affect both reproductive and non-reproductive systems. Within food production, some sex hormones are provided to cattle. The hormone bST is provided to dairy cows but other animals do not receive exogenous hormones. Plant hormones are vastly different from mammals but contain hormones similar to estrogen termed phytoestrogens. Phytoestrogens are currently being studied for health benefits and have demonstrated both estrogen/anti-estrogen like effects when acting on ERs. While hormone content varies throughout cattle and crops, amounts have been estimated within selected foods. Overall, hormones found in foods and within the body serve several roles that are still being explored.
Sources:
1. Jerry Tortora and Bryan Dickerson, Principles of Anatomy & Physiology, 16th ed. (New Jersey: John Wiley & Sons, 2021).
2. https://www.intechopen.com/chapters/75047#
3. Palacios OM, Cortes HN, Jenks BH, Maki KC. Naturally occurring hormones in foods and potential health effects. Toxicology Research and Application. 2020;4. doi:10.1177/2397847320936281. https://journals.sagepub.com/doi/10.1177/2397847320936281
4. https://www.fda.gov/animal-veterinary/product-safety-information/steroid-hormone-implants-used-growth-food-producing-animals#:~:text=Steroid%20Hormone%20Implants%20Used%20for%20Growth%20in%20Food%2DProducing%20Animals,-Share&text=Since%20the%201950s%2C%20the%20Food,testosterone%2C%20and%20their%20synthetic%20versions.
