Osteoporosis and Stress Response
As I see it, our skeleton is a “maternal giver,” always ready to sacrifice itself for the higher survival needs of the whole. For example, if blood calcium drops to a threateningly low level, the skeleton immediately breaks itself down infusing a life-sustaining level of calcium into the blood. If blood pH takes even a slightly acidic tilt, again bone willingly sacrifices its alkalizing mineral compounds to reestablish the obligatory blood pH balance. Now scientists have discovered a new fascinating and unexpected way bone protects the whole-body system—the role that our skeleton plays when we face danger. Here’s the hot-breaking scientific story and what it might suggest for how our bones are weakened by stress.
For more than two decades, researchers at Columbia University have studied the bone protein known as “osteocalcin.” Osteocalcin is the bone-produced protein responsible for the formation of new bone. Osteocalcin forms new bone, but it also leaves bone to play many other roles well beyond its skeletal role—the most recently discovered of which is the role of osteocalcin in our response to stress. In short, scientists now report that our bones guarantee that we have the get up and go to either “fight or flee” when faced with life-threatening danger (1).
The chart below summarizes this biochemical tale:
- When faced with danger the brain registers a fear response in its amygdala.
- This alarm signal gives the call for the specific activated form of osteocalcin to be sent to the blood.
- To provide for this active form of osteocalcin (as opposed to the inactive form) the bone-forming osteoblasts increase their uptake of the neurotransmitter glutamate—this neurotransmitter prevents inactivation of the osteocalcin.
- Active osteocalcin is then sent flooding into the blood stream.
- Active osteocalcin then “turns off” the “rest and digest” parasympathetic nervous system.
- With the counter-balancing parasympathetic nervous system turned off, the “fight or flight” sympathetic nervous system is allowed to run full tilt without any brakes.
- The unrestrained “fight or flight” response fuels the body with high powered stress hormones fueling an immediate and robust response to the danger.
Few if any researchers expected bone to play a role in our stress response, but this new finding makes sense. During the long course of human evolution, immediate survival was the most compelling need, and certainly an area where there was redundancy would hold a selective advantage. Just as nature provided humans with two eyes, two sets of lungs, two kidneys, two sets of hands, etc., nature also provided for a bone-centered backup response to life-threatening danger. Our skeleton, we now know, serves along with the adrenals to guarantee a robust flight or fight survival response. In fact, this new research found that bone response to danger occurs before the adrenal hormones have time to kick in and it will occur even if the adrenals are removed or non-functional.
During three decades of clinical nutrition practice, I have documented the direct link between osteoporosis and stress response. Indeed, I was one of the first to say that stress could contribute to, and even by itself, cause osteoporosis. Now we have a mechanism to help explain this clinical observation. And interestingly enough, this new discovery of bone rescuing our stress response fits well with Traditional Chinese Medicine, which for thousands of years has held fear to be the emotion causing bone weakening.
Does bone suffer as it donates its osteocalcin to respond to acute stress?
It is obvious that the body has only a finite pool of resources and energy available for its use. In all its wisdom, and on a minute-by-minute basis, the body decides where to invest its energy and resources. Noting that so many of my bone health clients were anxious and extremely worried, I often speculated that the body might be spending its energy and resources on this fear response rather than building bone. Now we know that this is a real possibility. Activated osteocalcin is produced by the bone-building osteoblast cells. These cells can only produce so much osteocalcin, and I suspect that the expenditure of osteocalcin on the fear response will limit the osteocalcin available for building new bone.
Can our skeleton’s role in supporting acute stress contribute to osteoporosis?
While there is not likely to be a problem if our bone–building osteocalcin is called upon once in a while, when stress is all too often long-term and chronic as in today’s fast-paced society, when self-perceived danger becomes an everyday affair, and when the feeling of anxiety is more common than the feeling of ease, bone is likely to suffer. One entire step of the Better Bones, Better Body Program, in fact, is dedicated to stress and worry reduction.
In you are interested in creating emotional resilience in your life, check out a few of our materials on the topic.
- Berger, J. M., P. Singh, L. Khrimian, D. A. Morgan, S. Chowdhury, E. Arteaga-Solis, T. L. Horvath, A. I. Domingos, A. L. Marsland, V. K. Yadav, K. Rahmouni, X. B. Gao, and G. Karsenty. 2019. Mediation of the acute stress response by the skeleton. Cell Metabolism 30(5):890-902.e8.