Osteoporosis 6- Chronic Stress (addendum)

I wanted to another thought on cortisol and the influence on bone.  Many people have heard of cortisone.  You may have received a cortisone injection for a nagging tendinitis or recurrent musculoskeletal complaint.  Many physicians will limit the number of cortisone injections a person can receive at the same site per year.  In other words, if you have an injection in the elbow, most physicians will not allow more than 3 per year.  The primary concern is the potential side effects including bone loss and joint damage to the area it is administered.

The point here is not to discuss the correct use of cortisone injections.  Personally,  I feel they can be remarkably helpful in some situations.  But understand that cortisone and cortisol are biochemical siblings.  They are very similar in function.  If doctors worry about cortisone destroying bone, then we are right in our thinking that chronic cortisol production in the body (due to stress) also wreaks havoc on bone.

Osteoporosis 5- Chronic Stress

There are 2 types of stress responses in our lives; a short term response and a long term response.  The short term response is considered to be governed by the sympathetic nervous system.  The long term response characteristically involves the release of glucocorticoids, namely cortisol. 

We've already discussed the fact that many people have overactive sympathetic nervous systems.  This has an immediate impact on bone.  We saw in a previous post that sympathetic dominance will inhibit osteoblast activity and increase bone resorption (breakdown).   In fact, much has been written about the more typical stress response seen in America; a prolonged short term response layered over an ongoing long term response.  It's worth noting here the influence of the long term response on bone health.

A 2008 paper does a good job describing the role of stress.
"Cortisol excess inhibits bone formation, increases bone resorption, impairs calcium absorption from the gut, and affects the secretion of several hormones (in particular gonadotropins and GH), cytokines, and growth factors, influencing bone metabolism." 

Remember that cortisol is considered a "stress hormone" and is released in times of physical, emotional or psychological stress.  It is a normal response but in a stressed out world, tends to get hyperactive.  The authors continue,

"Subclinical hypercortisolism, a condition of impaired hypothalamic-adrenal axis homeostasis without the classical signs and symptoms of glucocorticoid excess, is a recently defined entity, which has been shown to be associated to increased bone resorption, bone loss, and high prevalence of vertebral fractures regardless of gonadal status."

You could still ask, "is this common or a rare event?"  The authors conclude,

"recent data suggest that subclinical hypercortisolism is a common and underrated finding in patients with established osteoporosis."   J Endocrinol Invest 2008 Mar;31(3):267-76

There are scores of papers the describe the role of stress in degrading bone health.  Attempts to manage osteoporosis without considering the stress response will likely fall short.

Osteoporosis 4- Magnesium

There's a lot of talk about the importance of calcium.  This is warranted.  But another very essential mineral often gets left behind in the discussion.  Magnesium has a huge role in maintaining bone health. Nearly 2/3 of your bodies magnesium is stored in bones.  Unfortunately...

"About 60% of adults in the United States do not consume the estimated average requirement for magnesium, but widespread pathological conditions attributed to magnesium deficiency have not been reported. Nevertheless, low magnesium status has been associated with numerous pathological conditions characterized as having a chronic inflammatory stress component."   Nutr Rev 2010 Jun;68(6):333-40

Among women, who are far more susceptible to osteoporosis, "the average dietary Mg intake... is 68% of the RDA, indicating that a large proportion of our population has substantial dietary Mg deficit."  This level of magnesium deficiency has the effect of, "decrease in osteoblasts and an increase in osteoclasts..." J Am Coll Nutr 2009 Apr;28(2):131-41

What's equally concerning is that researchers found that magnesium deficiency led to an increase in production of inflammatory signals like substance P, TNFalpha and IL1beta.  (We will address inflammation in a separate post).

It is clear that when dietary magnesium is low, there are a few ways that your bones suffer; bone making cells decrease activity, bone degrading cells increase activity, and inflammation will degrade bone. 

Pumpkin seeds, spinach, swiss chard, almonds, black beans and navy beans are excellent sources of magnesium.

Osteoporosis 3- Fight or Flight

The so called "fight or flight" response is mediated by something called your sympathetic nervous system.  It is considered your short-term stress response (your long-term stress responses is mediated by a different but very closely related system).  Many individuals experience chronic activation of this "fight or flight" system.  In reality, this physiological response is supposed to engage when needed and then turn off when there is no immediate need for it.  Unfortunately, our crazy world and busy lives often induce chronic activation of your sympathetic system.

For example, it is well known that obesity promotes excessive sympathetic activation.  We are still learning why this happens, but several ideas have been proposed.

"Several mechanisms have been proposed to explain the SNS activation in obese subjects; increased leptin concentration, hyperinsulinemia, obstructive sleep apnea, decreased arterial baroreflex sensitivity, elevated plasma angiotensin, obesity-related kidney disease and lack of exercise." Int J Hypertens 2011; Jan 20:642416.

Even in non-obese individuals, it is not uncommon to have excess sympathetic activation.  This is consistent with the dramatic rates of hypertension, fast resting heart rates, poor digestion, erectile dysfunction etc.  All these problems, while multi-faceted, have a layer of excess sympathetics.  Now let's consider bone health.

Does the sympathetic dominance commonly seen influence bone metabolism?  The answer is, yes.

"...increasing clinical and experimental evidence has driven attention towards the pivotal role of the sympathetic nervous system (SNS) in bone remodeling" Ageing Res Rev 2011 Jan 22.

"...sympathetic nervous system inhibits bone formation and increases resorption due to the binding of catecholamines to receptors located in osteoblasts."  Eur Rev Med Pharmcol Sci 2009 May-Jun;13(3):157-62

What does this mean for the average person concerned with their bone health?  It means calm down your sympathetic nervous system.  I realize this presents a big bag of worms that poses the question, "how do you calm down sympathetics?"  We'll address some of the science at a later point, but for now...a healthy lifestyle; eating lots of plants, regular exercise, stress management, lots of water and general avoidance of the "bad stuff."  I realize this isn't exactly a thrilling game plan.  But when you understand that a poor lifestyle influences bone health in a myriad of ways, it is my hope that that will be greater motivation for you to stick to it.  

If we were to stop this series right now, a healthy diet would help bones because:

1.  Decreasing sodium would decrease calcium excretion.

2.  You would calm down sympathetic dominance which would in turn, stop irritating the bones.

We'll continue on and expand our understanding of the many variables that influence bones.

Osteoporosis 2- Salt (& Hypertension?)

We all know that excessive amounts of salt are not good.  The link between sodium and hypertension is very well established although we're still learning more about the many ways that salt is damaging.  Salt can also adversely influence bone health. In fact, there is some suggestion that hypertension and bone health may be related.

Dietary calcium has long been considered an essential part of managing hypertension.  Researchers are unclear on exactly how calcium is helpful, but it seems to be necessary.  Calcium supplements have thus far been controversial in lowering blood pressure as several studies indicate no effect.  (As a side note, this is further evidence that food is far more important than supplements).  But why all the talk about hypertension when we're discussing osteoporosis?  Because the two conditions appear to be linked.

This paper cites a genetic link between the two conditions and it cites several studies that show that managing blood pressure can actually improve bone health.  ACE inhibitors are a common medication used to lower blood pressure; a helpful side effect is that they seem to help bone density.  Don't consider this my endorsement of a purely pharmacological approach to managing bone density.  Consider this as evidence that the biology of the two conditions are connected.  So what?

It has long been known that excess salt intake will increase calcium excretion through the kidneys.  In other words, the more salt you ingest, the more calcium you will pee out.  When so many Americans struggle to take in sufficient amounts of calcium, it would seem wise to keep as much of it in our body as possible.  In fact, people with higher sodium intake have been shown to have lower bone mineral density.

Step number 1 in improving bone health; watch your salt intake.  It may help lower your blood pressure too.