SIBO: The Link between SIBO and Hormonal Health
When I was at my worst during my SIBO journey, my hormones were all over the place. My thyroid hormones were shut down, my cortisol levels rising so high that my GP ordered multiple blood, saliva and urine cortisol tests to confirm it wasn’t a lab mistake, my sex hormones (estrogen and DHEA) were missing in action and my libido well…no need to even go there!
If you don’t know what SIBO is, make sure to read my article on SIBO first.
The Connection Between Hormonal and Gut Health
This pattern of lowered thyroid hormones, elevated cortisol, and imbalanced sex hormones is actually very common in people dealing with SIBO. Reason is, there is a clear connection between hormonal health and gut health.
This raises the question: does hormone dysfunction contribute to SIBO, or does SIBO cause hormone dysfunction? While it is almost impossible to answer this question confidently, it is reasonable to think that an imbalanced gut will lead to hormonal disruptions and vice-versa. Let’s have a look.
SIBO, Inflammation and Nutrient Deficiencies
The main impacts of SIBO are three-fold. The excessive proliferation of bacteria in the small intestine trigger inflammation, hinder the absorption of essential nutrients and produce enzymes that affects our hormonal metabolism.
This disruption significantly influences the production and regulation of many hormones.
Inflammation
The overgrowth of bacteria in the small intestine (where they shouldn’t be) prompts the body's immune response, initiating inflammation. This inflammatory process can impede the normal operation of the endocrine system, responsible for hormone production and regulation. The resultant irregularity in hormone production manifests in a broad spectrum of symptoms and health complications.
Nutrient Deficiencies
Beyond inflammation, SIBO has the potential to compromise nutrient absorption. The small intestine, tasked with extracting nutrients from food, encounters competition for these nutrients when bacteria multiply and overgrow and start fermenting these partially digested foods. This puts the body at risk for deficiency in the fundamental building blocks necessary for optimal hormone synthesis.
Metabolic Enzymes
Moreover, bacteria present in the intestines can produce a variety of enzymes (such as β-glucuronidase) that modify hormone metabolism. These enzymatic alterations can affect the function and excretion of hormones, contributing to imbalances throughout the body.
Impact of SIBO and Dysbiosis on Hormones
Current research indicates that Small Intestinal Bacterial Overgrowth (SIBO) can disturb the equilibrium of multiple hormones within the body. When bacterial overgrowth is present, it always comes with dysbiosis, an imbalance of gut bacteria which affects multiple endocrine systems.
Thyroid-Gut Connection
Imbalances and inflammation in the gut can suppress thyroid function in various ways. Gut bacteria play a crucial role in activating thyroid hormones, converting T4 to T3, and disruptions in this process occur when the gut environment is compromised. SIBO can disrupt the absorption of essential nutrients required for proper thyroid function, leading to symptoms like weight gain, fatigue, and mood disturbances.
Endotoxins (LPS) produced by opportunistic gut bacteria can also negatively affect thyroid function by reducing hormone conversion and impacting thyroid receptors. Inflammation from the gut also elevates cortisol levels, further downregulating thyroid function.
Adrenal-Gut Connection
The intricate connection between the brain and the gut via the gut-brain axis influences cortisol levels and the body's response to stress. Communication between gut bacteria and the brain, facilitated by the vagus nerve, modulates cortisol regulation. When there is inflammation and dysbiosis in the gut, the receptors send a signal to the brain that we are under attack (stressor). This leads to increased cortisol levels secreted by the adrenal glands via the hypothalamus-pituitary-adrenal (HPA) axis.
Probiotics, by enhancing gut health, have shown promise in mitigating the stress response.
Sex Hormones-Gut Connection
SIBO sufferers commonly experience symptoms such as low sex drive, irregular menstrual cycles, and infertility, reflecting the influence of an unhealthy gut on sex hormones. SIBO has been associated with disturbances in various hormones, encompassing estrogen, progesterone, testosterone, and thyroid hormones. As we just saw, an inflamed gut disrupts thyroid and cortisol balance, crucial for maintaining healthy sex hormone levels (this is a discussion for another blog post but know there is a concept known as the cortisol steal). Additionally, gut bacteria directly impact the metabolism of sex hormones, with certain bacteria playing a role in estrogen metabolism, for example. They have been collectively named the estrobolome (explained below).
Estrogen is pivotal in the female reproductive system and when imbalanced due to SIBO, can lead to menstrual irregularities, fertility challenges, and mood swings.
What is the Estrobolome?
A collection of your bacteria —known as the estrobolome— is responsible for one very important hormonal function: metabolizing estrogen. An imbalance among these bacteria can affect estrogen levels and, consequently, may have implications for conditions related to hormonal balance, such as certain reproductive disorders.
Testosterone, commonly linked with male characteristics but present in females in smaller quantities, can be influenced by SIBO. This impact may manifest in symptoms such as reduced libido, fatigue, and negative changes in muscle mass.
Testosterone levels often become effected when your gut is inflamed. Leaky gut (intestinal permeability) can lead to trans mucosal migration of endotoxins from the gut to the gonads, resulting in decrease of testosterone production. If your sex drive has been non-existent, low testosterone levels may be at play.
Progesterone on the other hand is a vital hormone in women responsible for sustaining a healthy pregnancy and regulating the menstrual cycle. Discrepancies in progesterone levels may result in irregular periods, difficulties conceiving, and an elevated risk of miscarriage.
It has been shown in numerous studies to affect gastric emptying and gut transit time (gastrointestinal motility). In people with SIBO, this is a huge deal as we want to make sure our motility is adequate and that the migrating motor complex can do its job. This is a perfect example of the impact of gut health on hormones as well as the impact of hormones on gut health in a bi-directional fashion.
In conclusion, I want to point out that while this is a long list of hormonal interactions with gut health, the impact of SIBO and dysbiosis on hormonal health varies greatly among individuals.
I recommend seeking guidance from a practitioner to better understand and address the specific hormone imbalances you might be dealing with.