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Are you one of the 20 million Americans who has thyroid disease? (1) Have you taken proactive steps to improve your thyroid health, such as cleaning up your diet and supplementing with thyroid-supportive nutrients, but with little to no improvement? If this sounds like you, you may be missing a big piece of the thyroid puzzle—chronic stress.
But how does chronic stress cause hypothyroid symptoms? And, if your day-to-day experience is consistently stressful, how can you correct it? Read on to learn more about the stress–thyroid connection and get 12 tips on reducing stress in your daily life.
What Is “Adrenal Fatigue” and Is It Real?
Chronic stress has become epidemic in our society. Many people live by the motto “the busier, the better,” adding an ever-increasing number of obligations to their already jam-packed schedules.
Unfortunately, our high-paced lifestyles are not without health repercussions. Sixty to 80 percent of office visits to primary care providers may be stress related, according to statistics. (2) Healthcare practitioners working in the integrative and Functional Medicine communities also see their fair share of patients with stress-related illnesses; for years they’ve used the term “adrenal fatigue” to describe the stress-related health problems observed in these individuals.
The adrenal fatigue hypothesis asserts that chronic stress causes the adrenal glands, which are one component of the body’s stress-management system, to weaken over time. This “weakening” then causes a range of nonspecific symptoms, including:
- Brain fog
- Joint pain
- Weight gain
The theory of adrenal fatigue may be popular, but does it hold up to scientific scrutiny? Surprisingly, the answer appears to be a resounding “no.”
When we dig into the science and the studies that back it up, it becomes clear that so-called adrenal fatigue is an oversimplification of the body’s stress response. And while there are some cases in which a person’s adrenal glands are functionally compromised, these situations are rare.
There are three main problems with the adrenal fatigue hypothesis:
- Those who subscribe to this theory maintain that the major stress hormone cortisol rises in the early stages of the disorder and decreases in the later stages, depleting as the adrenal glands become “fatigued.” However, many people with stress-related pathology have normal or high cortisol, rather than the low cortisol purported to occur in adrenal fatigue.
- They also argue that abnormal cortisol production is the fault of the adrenal glands. However, the adrenals aren’t the primary controllers of cortisol production—the central nervous system is. In stress-related illness, the problem lies in the brain, not the adrenal glands.
- The scientific literature does not support the concept of adrenal fatigue. A systematic review of the literature, published in 2016, found no evidence to support it. (3)
If it can’t properly be called adrenal fatigue, then what is it?
A more accurate term that is increasingly used by integrative and functional health practitioners to describe stress-related illness is hypothalamic–pituitary–adrenal (HPA) axis dysfunction.
Unlike adrenal fatigue, HPA axis dysfunction is biologically plausible, well studied, and associated with numerous health problems, including: (4, 5, 6, 7, 8)
- Cardiovascular disease
- Neurodegenerative disease
- Chronic fatigue syndrome
If Adrenal Fatigue Isn’t to Blame, What’s Really Happening?
The HPA axis is the body’s central stress response system, formed by an intertwining of the central nervous system and endocrine system. It orchestrates the response of the body and brain to cues from the environment, including positive and negative stressors. The three primary structures that comprise the HPA axis are the hypothalamus and pituitary gland, located in the brain, and the adrenal glands, which sit atop the kidneys.
When the body experiences stress, the following four-step response is normally produced by the HPA axis.
Step 1: In response to a stressor, the hypothalamus releases a hormone called corticotropin-releasing factor (CRF).
Step 2: CRF travels from the hypothalamus to the pituitary gland, where it binds to CRF receptors. This stimulates the pituitary to release adrenocorticotropic hormone (ACTH).
Step 3: ACTH travels in the bloodstream to the adrenal glands, where it promotes the adrenal release of cortisol in the right quantities to protect the body from stress.
Step 4: When the stress response lasts long enough to cause cortisol to reach a certain concentration in the blood, negative feedback is relayed to the hypothalamus. This feedback tells the hypothalamus to stop releasing CRF, effectively halting the stress response.
What You Need to Know about HPA Axis Dysfunction
The stress response described above helps us manage short-term stressors. It evolved over millions of years in our hominid ancestors, enabling them to efficiently respond to short bursts of stress, such as being chased by a predator on the African savanna, and then return to an unstressed state once the stressor was removed. Unfortunately, many of us today live in a state of chronic (ongoing) stress, rather than acute (short-burst) stress.
Chronic stressors such as rush-hour traffic, work-related and financial stress, relationship challenges, gut dysbiosis, blood sugar dysregulation, and environmental toxins overwhelm our HPA axis, which was designed to deal with acute stressors. Long-term activation of the HPA axis reduces our metabolic reserve—the ability of our cells and organs to withstand repeated physiological changes.
Think of metabolic reserve like a rubber band. Stretching the rubber band every now and then doesn’t alter the rubber band very much. However, repeatedly stretching the band eventually causes it to lose elasticity and become permanently elongated. Similarly, short, intermittent bouts of stress are efficiently handled by cells and organs, while chronic stress causes harmful changes to our systems.
In a state of chronic stress, the body does everything it can to preserve metabolic reserve. As a result, one of two situations takes place in the HPA axis:
- The negative feedback mechanism in the HPA axis is desensitized, leading to extended HPA axis activation. Think of this as the body’s attempt to continuously stay “on guard” for potential threats.
- The negative feedback mechanism becomes overly sensitive and limits the stress response in an attempt to protect the body. In this case, the HPA axis can’t appropriately respond to stressors, leaving the body vulnerable to new threats such as pathogenic bacteria and toxins.
In both cases, these adaptations serve an important immediate purpose: to protect your body’s metabolic reserve. However, if chronic stress continues, metabolic reserve is eventually depleted. This changes cortisol output, increasing or decreasing it, or changing your diurnal cortisol rhythm. (Cortisol is a diurnal hormone, meaning that it’s not secreted uniformly throughout the day; normally it’s highest in the mornings and declines throughout the rest of the day and into the evening.) The production of other hormones and neurotransmitters, such as DHEA, melatonin, and epinephrine (aka adrenaline), is also impaired, which will impact multiple organ systems. HPA axis dysfunction is the term used to describe the physiological changes and associated symptoms that occur in response to chronic stress.
As you can see, stress-induced health problems are not simply the result of “weak” adrenal glands; instead, these issues are manifestations of stress-induced dysfunction that begins in the brain and ultimately affects the entire body. One of the most important organs affected by HPA axis dysfunction is the thyroid gland.
The HPA Axis–Thyroid Connection
Every cell in the body has receptors for thyroid hormone. Thyroid hormones regulate and impact all body systems. When the thyroid malfunctions, it takes the entire body down with it.
If you have thyroid problems, you’re not alone. An estimated 20 million Americans have some form of thyroid disease, and it’s likely that 60 percent of those with a thyroid condition are unaware of it. (9) Hypothyroidism, a form of thyroid disease associated with decreased function of the thyroid gland, causes a variety of symptoms:
- Fatigue despite sleeping eight to 10 hours a night; needing naps during the day
- Weight gain or inability to lose weight
- Mood swings, anxiety, and depression
- Brain fog, poor concentration, and poor memory
- Cold hands and feet
- Hair loss
- Dry or cracking skin
- Neck swelling and a hoarse voice
With 121 million prescriptions written annually, the use of levothyroxine, a synthetic thyroid hormone medication, far outpaces statins and blood pressure medications in the United States. (10) Nonpharmaceutical interventions, such as diets and supplements, are also widely used by patients with hypothyroidism. Unfortunately, the reality is that these interventions will all fail unless people address the underlying causes of their thyroid health issues.
A crucial contributor to thyroid disease that tends to be overlooked by both thyroid disease patients and their doctors is chronic stress.
How Does Your Chronic Stress Cause Hypothyroid Symptoms?
The thyroid gland is intimately connected with the HPA axis. When chronic stress alters HPA axis activity, a cascade of effects ultimately disrupts thyroid function.
Stress Depresses HPA Axis Function
Chronic stress promotes the release of inflammatory cytokines, small proteins that interfere with the HPA axis and reduce hypothalamic and pituitary function. (11, 12) The hypothalamus and pituitary glands are responsible for making thyrotropin-releasing hormone (TRH) and thyroxine-stimulating hormone (TSH), respectively. In a healthy human body, TRH and TSH travel to the thyroid gland and stimulate it to produce the thyroid hormones triiodothyronine (T3) and thyroxine (T4). When the HPA axis is suppressed or slowed down due to stress, TRH and TSH levels decrease. This chain of events leads to lower circulating levels of T3 and T4 and promotes the development of hypothyroidism.
Stress Reduces Active Thyroid Hormone Levels
As I mentioned above, the thyroid gland produces two hormones, T3 and T4. The majority of hormone produced by the thyroid is inactive T4, which must be converted into active T3 in peripheral tissues and organs before binding to thyroid hormone receptors on cells. Stress initiates the release of inflammatory cytokines that inhibit the conversion of inactive T4 to active T3. This results in lower circulating levels of thyroid hormone. Given the fact that all body cells have thyroid hormone receptors, the reduction in active T3 has adverse health implications for many body systems. (13, 14, 15)
Stress Promotes Thyroid Autoimmunity
Chronic stress was first identified as a risk factor for autoimmune disease over 50 years ago by Dr. Hans Selye, a pioneering endocrinologist who dedicated much of his career to studying the stress response. (16) We now understand that stress-induced HPA axis dysfunction changes levels of certain hormones that regulate immunity. These hormones alter cytokine production, which, in turn, can trigger immune dysregulation and autoimmune disease. (17, 18, 19) While scientific evidence demonstrating a direct relationship between stress and autoimmune hypothyroidism is lacking, several studies have identified stress as a factor in the development of Graves’ disease (autoimmune hyperthyroidism) and rheumatoid arthritis. (20, 21)
Given this evidence, it’s likely that stress also plays a significant role in the development of autoimmune hypothyroidism, also known as Hashimoto’s disease.
Stress Causes Thyroid Hormone Resistance
Thyroid hormone receptors control the process of transcription, the first step of gene expression, in which DNA is copied to make RNA. The central role of thyroid receptors in gene expression means that thyroid hormones have effects on all cells of the body. Inflammatory cytokines produced by chronic stress suppress the sensitivity of thyroid hormone receptors to thyroid hormones. (22) Reduced binding of thyroid hormone to its receptors prevents thyroid hormone from performing its crucial gene expression-regulating functions. This means that stress can impair the function of all cells of the body!
Stress Causes Imbalances in Other Hormones
Chronic stress doesn’t just reduce thyroid hormone levels; it also alters levels of other hormones that indirectly influence thyroid function, such as estrogen. It goes something like this: Prolonged cortisol release due to chronic HPA axis activation decreases the liver’s ability to process estrogen. Estrogen increases levels of thyroxine-binding globulin (TBG), a protein that binds thyroid hormones in circulation and inactivates them. High estrogen caused by chronic stress can cause hypothyroidism by reducing circulating levels of free, active thyroid hormone. (23)
These mechanisms indicate that chronic stress can cause hypothyroidism without any problem in the thyroid gland itself. Given the influence of stress on thyroid function, stress-reduction strategies should be a central part of any protocol designed to improve thyroid health.
12 Ways to Reduce Stress and Improve Your Thyroid Function
The implications of stress for thyroid health, and the health of the entire body, can’t be ignored. Thyroid-damaging stress can come in the form of physical, mental, and emotional stressors. Proactively addressing these stressors reduces the burden on the HPA axis and may improve your thyroid health.
1. Balance Your Blood Sugar
As I mentioned earlier, physical stressors activate the stress response and the HPA axis. Blood sugar dysregulation is a significant physical stressor that disrupts HPA axis function. Diabetes has been found to impair the HPA axis response to hypoglycemia, while insulin treatment to reduce blood sugar levels normalizes it. (24) By dampening HPA axis activity and normalizing the stress-related pathways that cause hypothyroidism, improved blood sugar regulation may boost thyroid function. For more information on the relationship between thyroid function and blood sugar, read my article “Thyroid, Blood Sugar, and Metabolic Syndrome.”
2. Heal Your Gut
Gut dysbiosis is another physical stressor that takes a significant toll on the HPA axis and thyroid function. Research has found that germ-free mice, which lack balanced gut microbiota, demonstrate increased HPA axis activity; this finding suggests that an abnormal gut microbiota activates the body’s stress response. (25) The gut–brain axis is linked to the HPA axis through certain neural pathways. Elevated levels of inflammatory cytokines and bacterial lipopolysaccharides in the gut, characteristic of gut dysbiosis, activate the HPA axis and raise cortisol. (26) In addition, multiple studies have linked gut dysbiosis to autoimmune hypothyroidism. (27)
Given the research, it’s reasonable to assume that gut dysbiosis may be a significant stressor underlying hypothyroidism. Correcting gut dysbiosis with antimicrobials, dietary modifications, and probiotics may help reduce the stress response. Probiotic strains that reduce HPA axis activity, as indicated by lowered cortisol and ACTH, include Lactobacillus plantarum, L. helveticus, L. fermentum, L. rhamnosus, and L. casei. (28)
3. Identify Your Food Intolerances
Anything that triggers inflammation in your gut is seen by your body as a physical stressor. Food intolerances are no exception. For example, non-celiac gluten sensitivity (NCGS) has been found to trigger inflammation of the central nervous system and cause gut–brain axis dysfunction. (29) The interconnection between the gut–brain axis and HPA axis suggest that NCGS, and potentially other food intolerances, may represent a form of chronic stress to the body. In the case of NCGS, avoiding gluten may reduce your body’s stress response and normalize your HPA axis activity.
4. If You’re Suffering from a Chronic Infection, Treat It
Chronic infections, such as Epstein-Barr virus and Lyme disease, cause the body to produce large amounts of inflammatory cytokines, which impact the HPA axis. (30) Resolving chronic infections reduces inflammation and can help normalize your HPA axis activity.
5. Avoid Environmental Toxins
Certain environmental toxins can disrupt the HPA axis and set off the stress response. In animal studies, bisphenol A (BPA) can cause hyperactivity of the HPA axis, resulting in anxiety and depression. (31) Lead, a heavy metal and a known neurotoxin, also induces HPA axis dysfunction. (32) Reduce your exposure to these and other environmental toxins by filtering your drinking and bathing water with a high-quality water filter and by using glass or stainless steel storage dishes and water bottles, rather than plastic.
6. Fix Your Sleep Cycle
Circadian rhythm disruption is a grossly overlooked but significant source of chronic stress that we all face in the industrialized world. Circadian rhythms are the set of biochemical processes in our bodies that follow an approximately 24-hour cycle and regulate many aspects of our behavior and physiology. Signals from our external environment such as light exposure, temperature fluctuations, and food intake sync our circadian rhythms. When we receive signals at inappropriate times during a 24-hour cycle, our circadian rhythms are disrupted and the physiological processes governed by those rhythms suffer. The HPA axis is one of the physiological systems impaired by circadian rhythm disruption. (33, 34)
Minimizing disruptions to your sleep cycle is crucial for normalizing HPA axis function and may improve thyroid health. To optimize your circadian rhythm, avoid blue light exposure at night by wearing blue light-blocking glasses. Banish all blue light-emitting devices from your bedroom, as even these seemingly benign light sources disrupt circadian rhythms. You may also want to stop eating at least three hours before bed because late-night eating enhances the stress response and induces circadian disruption. (35)
7. Take Sleep Seriously
Sleep deprivation is a significant source of stress for many people and has been associated with abnormal thyroid function. (36, 37) To reduce your stress and optimize the function of your HPA axis and thyroid, aim for seven to eight hours of sleep each night. The quality of your sleep is just as important as the quantity. Keep your bedroom completely dark and free of light pollution from street lamps, digital alarm clocks, and other electronic devices. If you struggle with disordered breathing issues, such as obstructive sleep apnea, I recommend you seek corrective help. Obstructive sleep apnea is associated with HPA axis dysfunction and a slew of other health problems, including subclinical hypothyroidism. (38) That’s where your TSH may be high, but your levels of other thyroid hormones are within a normal range.
8. Exercise, but Not Too Much
Exercise is essential for optimal health. However, over-exercising is not healthy; in fact, it activates the body’s stress response and causes serious damage both over the short and long term. The amount of exercise that a person can handle without going too far depends on the individual. For guidelines on how to avoid over-exercising while still enjoying yourself and getting benefits from physical activity, check out my podcast “Exercise and ‘Adrenal Fatigue’.”
9. Try Adaptogenic Herbs
Adaptogens are plants that help the body adapt to stress, protecting it through various mechanisms:
- Adaptogens induce the production of proteins that protect the cells when the body is under stress (39)
- Adaptogens increase neuropeptide Y, a stress-responsive hormone that stops the HPA axis from overactivating (40)
- Adaptogens modulate stress-induced gene expression (41, 42)
Ashwagandha, a popular adaptogen that has a long history of use in Ayurvedic medicine, has stress-reducing effects and has been found to improve thyroid function in those with subclinical hypothyroidism. (43) Rhodiola rosea, an adaptogen native to Siberia, increases neuropeptide Y and reduces the hypothalamic expression of the stress-related gene c-Fos. (44, 45) These adaptogens may be beneficial additions to protocols designed to normalize HPA axis activity and improve thyroid function.
10. Think about Your Stressful Experiences Differently
While all of us face stress in our daily lives, we can influence how we respond to stressors by changing how we perceive them. In psychology, this strategy is known as “reframing.” Reframing gives us some control over how we respond to stressful events in life and can thereby reduce our stress levels and HPA axis activity. You can read more about reframing, and how to incorporate it into your life, in my article “5 Simple (But Powerful) Tools for Fighting Stress.”
11. Start a Mindfulness Practice
While stress initiates the release of thyroid-damaging inflammatory cytokines, stress-reduction practices decrease these cytokines and may improve thyroid function. (46, 47) In a group of 80 healthy women, consistent mind–body training (MBT) decreased TNF-alpha and IL-6, two inflammatory cytokines that have been associated with impaired thyroid function. (48, 49) Mind– body training refers to a practice that incorporates rhythmic movements with deep breathing exercises and meditation. Yoga is another mindfulness practice that may improve thyroid function by reducing stress. A small study found that six months of yoga practice decreased TSH, an effect associated with increased thyroid function. (50) Mindfulness practices also tend to have antidepressant effects. Antidepressants have been found to directly improve thyroid function in rats. (51) Other stress-reducing, mood-boosting strategies that don’t involve antidepressants may also help hypothyroidism.
12. Make Play a Part of Your Life
Play is a powerful tool for reducing stress and enhancing resilience. (52) While play can take countless forms, it has one defining factor: it’s an activity you engage in for enjoyment or recreation. Here are just a few examples:
- Roughhousing with pets or children
- Playing make-believe
- Playing organized sports such as soccer, baseball, or basketball
- Engaging in other forms of physical activity such as rock climbing, skiing, surfing, or ultimate Frisbee
- Playing board games
- Going outside and walking in nature
- Engaging in creative expression such as making art, music, gardening, or cooking a meal
- Performing creative, innovative work (yes, work can be play!)
- Engaging in playful banter at your job or a party
- Having a playful relationship with your partner or spouse
Set aside time in your schedule for play, just as you would for other commitments such as work and exercise. I think you’ll find this to be one of the most enjoyable stress-reduction strategies listed here! You can read more about the benefits of play in my article “10 Benefits of Play.”
If you struggle with hypothyroidism and have tried medications, dietary changes, or supplements with minimal results, it may be time to consider the influence of chronic stress in your life. By taking proactive steps to reduce physical, mental, and emotional stress, you can set your body on the path toward optimal thyroid health.
Now I’d like to hear from you. Do you have questions about how chronic stress causes hypothyroid symptoms? Have you tried any of the stress-reduction strategies outlined in this article? Let me know in the comments below!
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