Stress: How does it affect your bones?

Reviewed By:
Lara Pizzorno – AlgaeCal Scientific Advisory Board Member
MDiv, MA, LMT
Best-selling author of Healthy Bones Healthy You! and Your Bones; Editor of Longevity Medicine Review, and Senior Medical Editor for Integrative Medicine Advisors.

About the Advisory Board Member

Stress is a normal human reaction that we all experience. Under most conditions, we see stress as a bad thing, but it’s important to keep in mind that some stress is good for us. For example, a tough workout or trying something new that challenges you can be stressful, but this type of stress, called eustress,  is positive or beneficial. It enhances your resilience instead of “stressing you out.¹ “

This article is all about distress, that too familiar “bad” stress that’s potentially harmful for us. Specifically, what happens in your body when you experience stress, and why unmanaged stress can unhappily affect the health of your bones.

Why Is Stress Harmful?

Acute stress is a natural part of life. You’re running late and get caught in a traffic jam. You feel anxious, your heart starts racing, your stomach muscles clench. Fortunately, such stress clears quickly. The traffic starts moving and you calm down.

When stress becomes chronic, however, its physical effects can lead to a range of imbalances in your mind and body. To understand why chronic stress is so harmful, let’s examine what happens in your body during the stress response.

The stress response, as defined by Hans Selye in his general adaptation syndrome model, involves three stages. Each of the stages in this model — alarm, resistance, and exhaustion — involves the body’s neuroendocrine system, which is influenced by psychological and physical stimuli.

In the first stage, alarm, (fight or flight) the body responds immediately to ‘perceived’ stress.

During resistance, the second stage of the stress response, the body tries to recover from the stressor.

The last stage, exhaustion, involves a continued, chronic response to stress. It may lead to a downward spiral of more stress, exhaustion, and disorders (including bone loss).²

So what does this general adaptation syndrome model look like in action?

A Closer Look at the Stress Response

During the alarm stage, when you encounter any real — or even any perceived — threat in your life, your body initiates a stress response to prepare you to cope with the danger. First, your HPA (hypothalamic-pituitary-adrenal) axis will become activated, prompting your adrenal glands to release stress hormones such as cortisol and adrenaline.³

These hormones shift your body from the parasympatheic nervous system’s “rest, repair and digest” state to the “fight or flight” state orchestrated by your sympathetic nervous system. The job of the sympathetic nervous system is to provide you with all the necessary resources to survive the real – or just imagined – threat confronting you.

Cortisol, your primary stress hormone, shuts down all non-essential-to-your-immediate-survival processes like immunity, reproduction, and digestion and boosts your available blood sugar so you have the energy to fight or get out of there as quickly as possible.

Meanwhile, adrenaline increases your heart rate and blood pressure and ramps up your breathing.

It also delivers other benefits such as:

1. Makes your lungs breathe more efficiently for better oxygen delivery to muscles
2. Shunts blood to the brain to improve alertness
3. Helps you think quickly 
4. Raises blood sugar for more fuel

Of course we can’t discuss the alarm stage without talking about another important brain structure. Here’s a hint: it’s the size of a small kidney bean and is practically next door neighbors with the hypothalamus and pituitary gland.

If you guessed amygdala, kudos — you’re right. This brain structure is responsible for detecting stress and sounding the alarm by telling the HPA axis to respond.

It also shares a special connection with the prefrontal cortex — the control center of the brain that controls thoughts and actions. This command center is a big region in the front of the brain. And it controls our emotional responses to stress by regulating the amygdala. 

So after the amygdala quickly signals a threat, the prefrontal cortex helps the amygdala to see stressful events as a little less scary.⁴ In doing so, it helps us avoid getting too stressed out. Now that’s a pretty sweet connection.

In an acute stress response, once the threat has passed, the hormonal cascade will resolve and your body will begin repairing itself.⁵ At this point your body is in a state of recovery — or the resistance stage.

However, when the threat is not readily resolved, the stress response remains active, which means that all of those “non-essential processes,” like digestion and reproduction (your endocrine system), continue to take a back-burner. 

In other words, a chronic stress response drains your body and leaves it operating on a deficit. And this puts your body in the last stage of the stress response, exhaustion.

How Does Stress Affect Your Bones?

Chronic stress, due to its many downstream side effects, affects your bones by disturbing a process known as bone remodeling.

What Is Bone Remodeling?

Bone remodeling is a process that your bones are constantly going through, which involves two types of cells; osteoblasts and osteoclasts. While osteoblasts are responsible for building your bones, osteoclasts help to resorb (break down) old bone tissue. 

This process takes a concerted effort on the part of both cells to maintain healthy, strong bones. When the process of bone remodeling is disturbed, it can result in a loss of bone integrity.

How Does Stress Impair Bone Remodeling?

Chronic stress can negatively impact the process of bone remodeling through several mechanisms:

1. Cortisol’s impact on calcium
2. Suppression of hormones
3. Inflammatory chemicals

Cortisol and Calcium

As mentioned previously, cortisol is released when you experience stress and starts a cascade of chemical reactions in your body. Among the many side effects of these reactions is a reduction in the availability of the mineral calcium.

Specifically, high levels of cortisol can impair your ability to absorb calcium in your intestine, which means that you can consume all the calcium-rich foods you like, but that calcium may never make it past your gut. Simultaneously, cortisol inhibits your kidney’s ability to reabsorb calcium and bring it back into circulation.⁶

Calcium (and its salts) are vital to bone density, making up about 65% of bone tissue. Therefore, a deficiency in this mineral can dramatically impact the health of your bones.⁷

Suppression Of Hormones

Due to its impact on your nervous and endocrine systems, chronic stress suppresses hormones vital for the growth, maturation, and maintenance of your bones.

Research shows that high stress can specifically impact estrogen and progesterone, two sex hormones that play a crucial role in bone integrity.^{8 9}

Furthermore, high stress levels are associated with suppressed growth hormone, which plays a role in bone turnover. Studies show that growth hormone not only increases osteoblast number and function, but it also stimulates bone resorption as part of the renewal process.¹⁰

Inflammatory Chemicals

Inflammation plays a direct role in skewing the process of bone remodeling towards resorption (breakdown) and away from the building mechanisms of osteoblasts. 

Chronic inflammation over-activates osteoclast cells that break down and remove your bone¹¹ 

In fact, recent studies show that chronic inflammation can elevate your osteoporosis risk by increasing your levels of inflammatory cytokines — which can induce bone loss.¹²

Stress and Osteoporosis

When new bone creation cannot keep up with the process of bone resorption, it can result in osteoporosis. In osteoporosis (which means “porous bone”), the honeycomb-like structure of your bone tissue changes, with the areas of density slowly diminishing. This creates weaker bones that are more prone to fractures and breaks.

Research shows that chronic stress is associated with an increased risk for osteoporosis for all of the reasons previously mentioned.^{13 14}

This means that managing your stress response could impact your health far beyond your emotional well-being. 

4 Tips For Reducing Stress

#1 Physical Activity

When you exercise, your body rewards you with the release of feel-good chemicals called endorphins. In addition, research shows that physical activity may increase serotonin and dopamine, two neurotransmitters involved in mood regulation.^{15 16 17}

And mechanosensors in our bones called osteocytes are sent strong signals to build new bone. Even just getting out for a short walk can make a difference in the way you feel.

#2 Bone Breathing

As described above, when your nervous system is in a state of fight or flight, your hormones kick in, and one of the side effects is faster breathing.

In this way, short breaths signify to your body that there’s a threat around. But the good news is that you can lower your stress levels and reduce your risk of excess bone loss with a simple practice called bone breathing.

Bone breathing involves focusing attention on various parts of the skeleton as you take slow, deep breaths.

When you take these long, deep breaths you signal your body that you’re safe. And this triggers your “rest and digest” mode, also known as the parasympathetic nervous system.¹⁸ It also helps your body release built-up stress. And as we covered, lowering stress can reduce excess bone loss.

#3 Meditation

Meditation, particularly mindfulness meditation, has recently gained popularity for its ability to help calm and focus the mind. Many people assume that meditation is about emptying the mind completely, which can make efforts to meditate incredibly frustrating.

The truth is that the nature of your mind is to be active, and mindfulness meditation is simply a way to notice the activity of the mind, not turn it off altogether.

When you create enough space to notice the activity in your mind, it feels less personal, and you can more objectively view your own thought processes.

Ultimately, most people find that by doing this, their mind quiets down naturally.¹⁹ This skill is very helpful in a stressful situation because it gives you options on how to respond to stress instead of letting your mind and body take you on the stress-hormone roller coaster.

#4 Laugh More

Everyone loves a good laugh, but most people don’t realize that laughing can actually have a profound effect on stress. In fact, research shows that laughing can decrease levels of the stress hormone cortisol.

Furthermore, the same neurotransmitters released during exercise (serotonin and dopamine) are also released when you laugh.

So if you’re feeling stressed, call up your funniest friend or throw on one of your favorite comedies and allow the laughter to do its work.²⁰

Takeaway

During an acute stress or threat, the physiological changes that happen in your body help you deal with immediate danger.

However, if the stress response doesn’t turn off, you could get stuck in a sympathetic nervous system response that hampers vital aspects of health like immunity, digestion, and hormonal function. Ultimately, this could lead to a host of issues – including bone loss.

While avoiding stress altogether isn’t possible, you can incorporate habits into your life to help you deal with stressors as they come up. Having tools for dealing with stress can help you navigate difficult situations and calm down that stress response before it goes rogue.

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References

1. https://www.merriam-webster.com/dictionary/eustress               
2. R. McCarty, “The Alarm Phase and the General Adaptation Syndrome” 2016 https://www.sciencedirect.com/topics/immunology-and-microbiology/adaptation-syndrome            
3. Mary Ann C. Stephens, Gary Wand. “Stress and the HPA axis.” Alcohol Res. 2012; 34(4): 468–483. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3860380             
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5. https://www.frontiersin.org/articles/10.3389/fphys.2020.00200/full 
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7. https://my.clevelandclinic.org/health/articles/15049-osteoporosis-prevention-with-calcium-treatment.
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12. Lia Ginaldi, Maria Cristina Di Benedetto, and Massimo De Martinis “Osteoporosis, inflammation and ageing” Immun Ageing. 2005; 2: 14. Published online 2005 Nov 4. doi: 10.1186/1742-4933-2-14.
13. Wippert, Pia-Maria, et al. “Stress and alterations in bones: an interdisciplinary perspective.” Frontiers in endocrinology (2017): 96.
14. Azuma, Kagaku, et al. “Chronic psychological stress as a risk factor of osteoporosis.” Journal of UOEH 37.4 (2015): 245-253.
15. Jackson, Erica M. “Stress relief: The role of exercise in stress management.” ACSM’s Health & Fitness Journal 17.3 (2013): 14-19.
16. Harber, Victoria J., and John R. Sutton. “Endorphins and exercise.” Sports Medicine 1.2 (1984): 154-171.
17. Marni N. Silverman and Patricia A. Deuster, “Biological mechanisms underlying the role of physical fitness in health and resilience” Interface Focus. 2014 Oct 6; 4(5): 20140040. doi: 10.1098/rsfs.2014.0040
18. Perciavalle, Valentina, et al. “The role of deep breathing on stress.” Neurological Sciences 38.3 (2017): 451-458.
19. https://www.apa.org/topics/mindfulness/meditation
20. Yim, JongEun. “Therapeutic benefits of laughter in mental health: a theoretical review.” The Tohoku journal of experimental medicine 239.3 (2016): 243-249.