6 Facts You Need to Know About the Hormone-Gut Connection

Written By


Expert Reviewed By

Dr. Lauryn Lax, OTD, MS

Dr. Lauryn, OTD, MS is a doctor of occupational therapy, clinical nutritionists and functional medicine expert with 25 years of clinical and personal experience in healing from complex chronic health issues and helping others do the same.

Hormones Hormone-Gut Connection

Your gut microbiome is the largest endocrine producing organ in the body—synthesizing and storing over 30 hormones in the body.

Hormone or thyroid imbalances got ya down? The answer to fixing them may be in your gut.

Here’s all you need to know about your hormones and how your gut microbiome influences them:

What Are Hormones?

Hormones are vital to every function of human life—keeping your body’s daily processes (like metabolism, digestion, growth, reproduction and mood) functioning in tip top shape.

You can think of hormones as your body’s special “chemical messengers” that are responsible for stimulating the trillions of cells in your body and their metabolic processes into action.

Hormones are created in either your brain (hypothalamus and pituitary) OR your endocrine (hormone) glands, like your thyroid, adrenal glands, ovaries and testes. Hormones control most major bodily functions, from simple basic needs like hunger and sleep, to more complex functions like reproduction, blood sugar levels, emotions and mood. 

Hormones You Need to Know About

Hormones On Different Parts Of The Body


Check out this overview of some of your primary hormones—many of which are produced or stored in your gut—and what they do in your body: 


Calcitonin. Prevents build up of calcium by decreasing blood levels; aids in the prevention of osteoporosis and the hardening of arteries as well

Insulin (β cells): Allows the body to use glucose or sugar from carbohydrates in the food for energy or to store glucose for future use. It also helps keep blood sugar levels from getting too high (hyperglycemia) or too low hypoglycemia)l

Glucagon (a cells): Helps absorb glucose into liver to form glyocgen

Ghrelin: “Hunger hormone” that tells your body it’s hungry

Growth Hormone: Stimulates growth of the body

Leptin: “Fullness hormone 


Antidiuretic hormone (ADH): Limits water expulsion by kidney. It also constricts blood vessels and rise blood pressure

Cholecystokinin (CCK): Stimulates fat and protein digestion in the intestines.

Gastrin: Secretes gastric juices for digestion.

Secretin: Maintains water levels and water balance in the body.





Adrenaline Hormone. The “emergency hormone” that helps initiates a  quick reaction to think and respond quickly to the stress. It increases the metabolic rate, dilation of blood vessels going to the heart and the brain.


Adrenocorticotropic hormone: Responsible for increased production and release of cortisol; Helps regulate your circadian rhythm

Aldosterone: Keeps electrolytes in balance, aids in sweat and saliva production

Cortisol: Your  primary “stress” response hormone that fights inflammation and stress (like a tough workout, running from a bear, or fighting traffic). Cortisol increases heart rate, blood pressure, respiration and your adrenaline response to cope with a situation. Chronically high levels of cortisol may cause gut problems, thyroid suppression, hormone imbalances, high blood pressure, anxiety, high cholesterol, decreased immunity and increased disease. Low cortisol can also trigger many of the same symptoms along with fatigue or low energy.





Estrogen: The main sex hormone for women. Responsible for reproduction, menstruation and menopause. Excess of estrogen in the females increases the risk of breast cancer, uterine cancer, depression, moodiness, PMS/PMDD, breast tenderness and infertility. Suppressed estrogen can lead to side effects like acne, skin lesions, thinning skin, hair loss, infertility, low mood, low energy and amenorrhea. In men, excess estrogen may cause: low libido and sexual dysfunction, man boobs, increased abdominal fat, low energy, loss of muscle mass, mood swings, blood sugar imbalances and non-cancerous enlargement of the prostate gland.


Follicle-stimulating hormone (FSH). Forms sperms in males and ova (eggs) in females.


Luteinizing hormone (LH). Formation of ova in females & production of testosterone.


Progesterone: A sex hormone, primarily in women, that assists estrogen in balance and function. Progesterone helps body to prepare for conception, pregnancy and regulates the monthly cycle. When pregnancy doesn’t occur, progesterone levels drop and menstrual cycle occurs. It also plays a role in the sexual desire.


Testosterone: The “male” sex hormone, although both men and women have it and need it maintain hormone balance. Testosterone is anabolic in nature (i.e. “building hormone”) and promotes: increased muscle mass and bone density, strength, hair growth, strong libido, increased mood and repair of body tissues. Low testosterone in men may lead to bone or muscle mass loss, low sex drive, brain fog and memory loss and increased fat tissue.

For women, high testosterone is associated with PCOS (polycystic ovarian syndrome), thinning hair on the scalp, excess body hair (chin, lip, abdomen), acne, increased muscle mass, weight gain, irritability, infertility, and deepening of voice. Low testate





Thyroid hormones regulate metabolism and calorie burning, heart rate, body temperature and gut motility (to prevent constipation). You have three primary hormones: TSH, T3, T4—all that work synergistically together.


TSH: The main thyroid hormone

T4: Inactive thyroid hormone that converts into active T3

T3: The “active” thyroid hormone that controls the majority of activity: regulates weight, determines energy levels, internal body temperature, skin, hair etc.


OTHER HORMONES (Mood & Body Functions)


Prolactin: Tells the body to make breast milk when a person is pregnant or breast-feeding.

Serotonin: Your mood-boosting effect hormone or also known as your “feel-good” brain chemical. 95% of it is produced in your gut. Serotonin aids in learning and memory, regulating sleep, digestion, regulates mood, some muscular functions etc. Low levels of serotonin cause depression, migraines, weight gain, insomnia, anxiety and sugar cravings. Excess levels cause agitation, confusion, diarrhea, headaches, shivering, twitching muscles and restlessness.



Gut-Hormone Basics

The gut microbiome plays a central role in the balance regulation of hundreds of hormones in your body. Your hormones—particularly stress and blood sugar hormones—also play a central role in keeping your gut microbiome balanced. The relationship is bi-directional.


When your gut bacteria are in proper balance, chances are your hormones are in proper balance, and they help the body regulate many of the automatic functions  that we don’t always think about.


However, if gut imbalances arise, you are more susceptible to hormone imbalances as well, affecting everything from mood and libido, to digestion, growth, body temperature, energy, immunity, absorption, blood sugar, and metabolism. Likewise, if stress or blood sugar imbalances arise, the more susceptible you are to gut and other hormone imbalances (thyroid, sex hormones) too.


Get the facts:


6 Cool Ways Your Gut & Hormones Are Connected


#1. Blood sugar imbalance and stress (in the gut) are the foundation of many hormone imbalances.

Blood sugar and insulin hormone levels play a key role in turning other hormones on, up or off. (Remember: Your blood sugar levels are your body’s report card of how well your gut bacteria use and absorb the energy you give it; as well as a reflection of how well your liver is working, if you’re eating a balanced diet (enough protein and fat), and getting enough sleep for a balanced gut microbiome) (1-4). If your blood sugar is off, hormone imbalances often follow—particularly your sex hormones and stress hormones.  Your gonadal organs (ovaries/testes that produce the sex hormones estrogen and testosterone) and your adrenal organs and hormones (cortisol, adrenaline) are highly sensitive to changes in insulin (blood sugar) and glucose. If blood sugar is too high or too low from stress (like gut stress and poor absorption; poor quality diet; lack of sleep; poor gut microbiome tissue repair; overtaxed liver; etc.), cortisol is called upon to help your body fight the stress and balance the blood sugar roller coaster going on inside. Consequently, chronically elevated or suppressed cortisol levels, in response to blood sugar levels, effect your hormones. For example, in the case of estrogen dominance in women, as the body responds to high levels of stress, it “steals” progesterone to continue manufacturing the stress hormone cortisol, leaving a relative excess of estrogen in the bloodstream (5). Another example commonly seen in PCOS is insulin resistance, where the pancreas pumps out more and more insulin in response to stress and high blood sugar levels ,  consequently causing cortisol, estrogen and testosterone imbalances (6, 7).


#2. Imbalanced gut bacteria triggers “estrogen dominance” (i.e. PMS, menopause, mood swings)

Normal healthy estrogen balance goes like this: (a.) Estrogen is produced by your ovaries, and then circulates throughout your body to other regions (like your uterus and breasts), until it reaches your liver where it is (ideally) inactivated. (b.) Inactivated estrogen is then sent to the intestine where it is supposed to stay inactive so it can exit the body through waste in your stool. However, if certain intestinal bacteria are present, something very different happens. Unhealthy bacteria produce an enzyme (beta-glucuronidase), which re-activates estrogen inside your gut; This re-activated estrogen then re-enters your body and can cause excess estrogen and the symptoms that go along with it (like PMS, menopause and mood swings) (8). For example: Women with endometriosis (characterized by estrogen dominance) have been found to have greater numbers of beta-glucuronidase-producing bacteria, as well as decreased healthy gut bacteria (Lactobacilli) and an increase in pathogenic gram-negative bacteria in the vagina and endometrium, further contributing to hormonal imbalance (9)


#3. Underlying gut stress is also correlated with low estrogen symptoms (i.e. low libido, amenorrhea, infertility)

If you have a gut issue, the body is under a lot of stress, making normal menstruation and hormone production difficult to continue and recover. Women with secondary amenorrhea (loss of period) often report symptoms like constipation and bloating. In addition, studies in women with eating disorders, like anorexia, commonly intertwined with secondary amenorrhea also have found significant differences in gut bacteria health both prior to recovery and after, suggesting dysbiosis, in addition to stress, may commonly be at play in women more prone to amenorrhea as well (10-13). Considering that Functional hypothalamic amenorrhea occurs when the hypothalamic-pituitary-ovarian axis is suppressed due to an energy deficit stemming from stress (i.e. weight loss independent of original weight, excessive exercise, disordered eating); and given the fact that gut microbes shape the architecture of stress reactivity of the hypothalamic-pituitary-adrenal axis (14), if the gut is unhealthy, neurotransmitters do not fire or stimulate effectively. Further research shows that therapies like cognitive behavioral therapy and probiotic use (healthy gut bacteria) have positive effects on decreasing stress levels in those with hypothalamic-pituitary-adrenal axis dysfunction to the point of improving both mood and mental health, as well as hormone balance and menstruation (15-19).


#4. Long-term birth control use is associated with bacterial overgrowth, like SIBO and gut “issues”
Small intestinal bacterial overgrowth (SIBO) and dysbiosis is observed in women who use contraceptives—both the birth control pill and vaginal inserts, like the “ring” (20-26). In fact, one of these  Harvard studies linked use of oral contraceptives to a 300% increase risk for Crohn’s disease. Furthermore, many women who have used a brith control method often report symptoms like constipation, IBS, bloating and/or hormonal imbalances (unwanted weight gain, acne, moodiness)—particularly when first starting or stopping the pill. Why? Such symptoms suggest a strong connection of gut bacteria and estrogen, also known as the “estrobolome”—microbes capable of metabolizing estrogens. Since birth control pills can supply your body with up to two to four times the amount of estrogen and/or progesterone your body naturally produces on its own, consequently suppressing your body’s own natural hormone production, since it is no longer needed. Unfortunately when you come off the higher dose of synthetic hormones, your natural hormones experience a dramatic shift. As your estrogen and progesterone levels are tanked, your cortisol levels (stress hormones) rise to alleviate the stress and establish homeostasis. The result? A stress response where we tend to feel stress the most—our gut—impacting not only digestive health, but also immune function and metabolic health.



#5. Testosterone improves when healthy gut bacteria is present.
Metabolic endotoxemia (gut stress and “leaky gut”) decreases your body’s natural production of testosterone (27)—a hormone needed in both men and women, in the right amounts, for libido, muscle and bone growth, metabolism, energy, mood and cognitive function. However, both animal and human studies have found significant positive improvements in testosterone when subjects are administered probiotics. In one study, researchers gave mice a probiotic strain called Lactobacillus reuteri and monitored their testicular size and testosterone levels, finding consistently, mice given the probiotic showed increased serum (blood) testosterone, larger testes & healthier sperm (28, 29). Conversely, in women with PCOS, characterized by elevated testosterone, probiotics had equal anti-inflammatory effects on testosterone, normalizing levels with administration (30).  Since the microbiome is greatly responsible for the management of inflammation throughout the entire body and low inflammation is necessary for healthy testosterone levels, then gut balance is a must.


#6. Unhealthy gut bacteria & gut stress promote thyroid dysfunction

Approximately 20 percent of T4 is converted to T3 in the GI tract, in the forms of T3 sulfate (T3S) and triidothyroacetic acid (T3AC). Then, the conversion of T3S and T3AC into active T3 (active thyroid hormone) requires intestinal sulfatase—an enzyme derived from healthy gut bacteria. Gut dysbiosis (imbalanced good and bad bacteria) and high cortisol from gut inflammation significantly reduces your body’s ability to generate healthy thyroid hormones. Stress and gut inflammation or dysbiosis are a big reason why people with poor gut function may experience thyroid symptoms as well as a heightened immune response (autoimmune thyroid symptoms) despite having normal lab results (31, 32). In fact, one study found that individuals who drink coffee within 60 minutes of taking their thyroid medication significantly reduces their body’s absorption of the hormone. Why? Stress in the gut (33).


The Bottom Line

A happy microbiome equals happy hormones.


Although research is really only in its infancy, if there is one “take home” lesson from this article is it this: Your gut microbiome and stress (both internal and external) play a vital role in practically every hormonal imbalance you experience.




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