Bone Health and Immunity

Bone Health and Immunity

Let’s watch some TV!

This is going to be a little unique since, unusually, I am not going to prattle on. Instead, I’m just going to sit back, at least for a while, and let you watch a video. It is interesting on so many fronts, the politics of space, human immunity, the role of bone marrow in aging and immunity, to name a few. I assure you that this is worth watching.

The video is part of a series on the immune system from UCSF and published by UCTV on YouTube. Frankly, they are all worth watching and I recommend them to you. Meanwhile, sit back; enjoy the show; and I’ll catch you later. Oh, and credit for the image of the International Space Station above goes to NASA.

The key to bone health is simple: weigh more!


I loved the entire story; but here I want to focus on what emerges from this presentation concerning bone health, exercise, and immunity. Note that there appear to be two systems impacted by low gravity: bone and immunity, more specifically, osteoporosis occurs and monocyte differentiation to macrophages et al is limited. The lack of gravity is causal in the failure of monocyte differentiation. This feature of immunosuppression simulates human aging; that is, the lack of gravity accelerates the osteoporosis and lowered immunity of aging.

The micro-gravity of spaceflight plays a broad role in gene expression within cells of the immune system. Perhaps, it might be better to say this the other way round; that is, that the gravitational force on the surface of the Earth plays a strong role in gene expression within cells of the immune system.

The stem cells that go to the thymus, which creates the T-cells of the immune system, come from bone marrow. As we age, we lose about 3% of our thymus each year. Interestingly enough, this is about the same rate at which we lose other athletic capabilities; e.g., running speed, & muscle strength. If you consider this in the 40-year span from age 25 to age 65, the reduction is around 1.03^40 = 3.25; that is, aging reduces the size of your thymus (or the size of your athletic prowess) to less than ⅓ of what it was in your youth. By the time you hit age 85, this factor has increased to almost 1/6th. So, the thymus of a child is larger by far than that of someone, say, over 60 years of age. This, naturally, limits T-cell production in older individuals. This is just one aspect of the Gompertz-Makeham curve (the exponential trend in degeneration and mortality with age) that I’ve discussed elsewhere on this site.

The doctor making the presentation speculates that the ultimate issue might have to do with the impact of gravity on lipid rafts within the T-cells. That may be. The more pertinent comment, to my way of thinking, is the observation that just as lowered gravity accelerates aging and immunosuppression, an increase in gravity does just the opposite. This raises the question of how to increase gravity.

Increasing gravity

What is gravity? Well, without getting into Einstein’s Theory of General Relativity for a deep answer, it is measure in terms of acceleration, meters (or feet) per second squared. How do we increase the gravity on our bodies? Two ways: increase our weight or increase the acceleration of our bodies. How do we increase our weight? Simple, we add weight to our bodies; this is nothing more or less than weight-bearing exercise, like weight lifting. How do we increase the acceleration that our bodies, and especially our bones, experience? Again, we perform exercises that increase the g-forces on our bones; for example, we run. A fairly simple calculation suggests that the g-forces due to running peak at about 3g; that is, each running stride increases your effective weight by about a factor of 3 over what you experience just standing. Actually, this is more like a 6-fold increase since that increased weight goes to each stride individually whereas your standing weight is distributed between each foot.

Not only does aerobic exercise strengthen your bones (this isn’t just me saying so, check out the National Osteoporosis Foundation for their viewpoint), but it is also turning on genes that up-regulate your immunity. The opposite is also true; sitting around all day and letting your body slide into the comforts of a weightless condition is going to turn off the genes that improve your immunity. Again, not just me saying so, the good Dr. Millie Hughes-Fulford reports this in her talk based on decades of experience with space flight.

Here is a really critical observation, for your personal health. Exercise does not just change your body by, say, toning your muscles and dropping your weight due to some training effect and increased energy consumption. It is changing your genetic structure. What is the point of a gene is it is turned off? If you want your immunity back, in the condition it was in your youth, then it is your job to turn those genes back on. Dr. Hughes-Fulford just told you how to do this.

Start walking or running or weight lifting or a little of each.

Every day.

How can I weigh more?

Lift weights and run!

No Time to Exercise?

Ask me how you can earn income and have the time to enjoy it.