Life Extension Magazine®

A New Cardiovascular Threat: Ionizing Radiation

CT scans emit ionizing radiation that forms senescent cells in the linings of arteries, increasing cardiovascular risks.

Scientifically reviewed by: Dr. Shaylind Benson, ND, on February 2020. Written By Jean Halstead.

It is wise to avoid unnecessary radiation exposure, in order to reduce risks of leukemia and other radiation-induced cancers.

CT scans are routine medical diagnostic tools, but the question about their safety has been a subject of debate for many years.

The ionizing radiation emitted by CT scanners is a cancer risk concern.

Mainstream publications argue the majority of exposure levels to ionizing radiation are too low to produce the DNA damage needed to initiate a malignancy.1-4

This is disputed by other researchers.5

An analysis published in Consumer Reports estimated that the 80 million CT scans performed in 2015 will eventually cause an estimated 29,000 cases of cancer.6

Medical imaging is a $100 billion per year industry,7 meaning there are financial incentives to downplay potential risks from radiation-emitting imaging devices.

And cancer is not the only health concern.

Life Extension® has warned for decades8-10 that radiation-emitting diagnostics are also linked to increased heart disease risk.

What’s new is a specific mechanism by whichionizing radiation damages coronary arteries that feed the heart muscle.

In a recent review of preclinical research, scientists have found a possible link between radiation-induced cell senescence and acceleration of cardiovascular disease.11

Exposure to radiation can either:

  1. Kill cells outright (which is the objective when treating cancer),

  2. Damage cellular DNA in ways that lead to malignant changes, or

  3. Create senescent cells that contribute to degenerative aging.

In this Research Update we’ll review recent findings on how ionizing radiation can create senescent cells that accelerate heart disease and other common disorders.11-13

Cancer, Apoptosis, or Senescence

Woman holding kale

What happens to a cell when it is hit by a beam of radiation or a charged particle moving at near light-speed?

That’s the question radiation researchers have sought to answer for decades, in an effort to understand how ionizing radiation interacts with living matter.14

It has long been known that both acute high-level exposure to ionizing radiation, and low-level chronic exposure could induce cancers.15

Cancers arise when particles in a beam of ionizing radiation break DNA strands in a cell’s nucleus.16 This sets off a potential cascade of events that leads from DNA damage to mutated cancer suppressor genes, to chaotic cell replication, and from there to a malignant tumor.

But cancer isn’t the only outcome facing a cell after being exposed to a beam of ionizing radiation.

Another result of radiation exposure is that the cell dies by a normal process called apoptosis. This is the principle behind radiation therapy in cancer treatment, whereby apoptosis is induced in most of the cancer cells, leaving the tumor to shrink and eventually undergo destruction by the immune system.17

If a cell doesn’t turn malignant, or die from apoptosis, it has a third pathway—it can undergo cellular senescence.17

Deadly Impact of Senescent Cells

A senescent cell neither dies nor becomes malignant. Rather, it loses its ability to function normally. These senile cells do not replicate or contribute to normal tissue functions.13

Senescent cells instead are a chronic source of localized and systemic dysfunction.

These “zombie-like” cells linger in tissues throughout our maturing bodies and accelerate pathological aging processes.

Senescent cells secrete a wide range of destructive chemicals, including protein-degrading enzymes that harm surrounding cells,18-20 as well as pro-inflammatory-signaling cytokines.13

Threat to Cardiovascular Health

In a review of numerous preclinical studies, researchers found evidence that ionizing radiation plays a significant role in endothelial cell dysfunction preceding the development of cardiovascular disease.11

They found that cells exposed to ionizing radiation are converted to senescent cells at an alarming rate, producing an inordinate number of senescent cells—particularly in the inner lining of our arteries called the endothelium.

Cells lining blood vessels (the endothelium) play active and diverse roles in maintaining health, including detecting and managing circulation and blood pressure.21

In less than a microsecond after exposure to ionizing radiation, endothelial cells undergo a stress response arising from the formation of reactive oxygen species induced by the radiation.11,22

This can cause endothelial cells to undergo premature senescence, which has been linked in preclinical research with early onset of cardiovascular disease.23

Radiation-induced senescent endothelial cells likely contribute to premature cardiovascular problems.

In addition to losing their ability to replicate, senescent endothelial cells develop defects in their ability to sprout, migrate, and form capillaries,13 meaning that they cannot help repair damage to heart muscle.

Major Medical Journals Recognize Anti-Aging Potential of Senolytics

As seen in Viewpoint, from the Journal of The American Medical Association, September 17, 2018

Scientific Discovery and the Future of Medicine

Aging as a Biological Target for Prevention and Therapy1

“…many human pathologic conditions are associated with the presence of senescent cells.”

“Interventions aimed at eliminating those senescent cells, commonly called senolytic, have also been shown to improve health and extend life in various mouse disease models.”

Scientific Discovery and the Future of Medicine

Aging, Cell Senescence, and Chronic Disease: Emerging Therapeutic Strategies2

“If senolytics are shown to be safe and effective in humans, they could transform care of older adults and patients with multiple chronic diseases.”

References: 1. JAMA. 2018;320(13):1319-1320. 2. JAMA. 2018;320(13):1321-1322.


Published in Perspective, from The New England Journal of Medicine, October 31, 2019

Enabling Healthful Aging for All…

“Moreover, tremendous advances are being made in our understanding of the science of aging, yielding exciting potential treatments that may alter the course of this inevitable process.1 One aspect of this work relates to ‘senolytics,’ the study of ways to either eliminate senescent cells that may have deleterious effects or slow or reverse the aging process by restoring cells’ lost function.”2

References: 1. Nature. 2019 Jul;571(7764):183-192. 2. N Engl J Med 2019; 381:1699-1701.

Arterial Damage and Blockage

Senescent endothelial cells lose their ability to respond to nitric oxide, the body’s natural signal to relax blood vessel walls. This leaves arteries with a permanent “squeeze” that ultimately drives up blood pressure and reduces blood flow.13

These senescent cells in the endothelium also stop producing anticoagulant factors, while increasing secretions of those that promote clotting. This increases the risk of a disastrous thrombosis, or blood-flow-stopping arterial clot.13

If all this sounds like a recipe for a heart attack or a stroke, it is.

And what’s worse, all this damage is now understood to happen at radiation exposures far lower even than those known to induce cancers.11,13

How much lower?

Even Modest Doses Concerning

Radiation doses are expressed in grays (Gy). A high dose is defined as greater than 2 Gy. A moderate dose is 0.1 Gy to 2 Gy.11

Low dose radiation is at or below 0.1 Gy.11

A person can receive as much as 0.1 Gy from a single CT scan.23 This means that people undergoing repeated CT scans can be hit with 0.2, 0.3, or more Gy of radiation.

That’s well within the moderate range seen in nuclear plant workers and even some survivors of the infamous Chernobyl nuclear power plant disaster.11,23

Avoid Unnecessary Radiation Exposure

An estimated 30% to 50% of imaging tests are believed to be medically unnecessary.7 That’s an alarming amount of dangerous radiation for patients that could be avoided, especially when there are alternatives such as ultrasound and MRIs.

Be sure to ask your medical professional if either ultrasound or an MRI could provide the diagnostic information they are looking for. Many times, these are acceptable alternatives that do not expose you to ionizing radiation, or as much radiation.

Life Extension® has been covering the science of senolytics to safely remove senescent cells from the body.

Now that we know that CT scans promote cellular senescence, it becomes more important to learn about senolytics and discuss this with your physician.

Life Extension® has published several articles about approaches people are utilizing today to reduce their senescent cell burden. To review these articles, log on to: LifeExtension.com/senolyticinfo

Summary

plants growing in a beaker

It is wise to avoid unnecessary radiation exposure. This helps reduce risks of leukemia and other radiation-induced cancers.

But new evidence shows that radiation may represent an under-recognized threat as well: premature cellular senescence, especially in endothelial cells, the layer of cells lining our blood vessels.

Unlike cancer-inducing radiation, which damages DNA strands at moderate and high radiation levels, senescence-inducing radiation has been shown at much lower levels, including those plausibly received from several CT scans over the course of a year.

CT scans can be lifesaving, and the risk must always be balanced against the benefits. Always discuss with your medical professional whether there are acceptable alternatives that do not expose you to ionizing radiation.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

References

  1. Available at: https://www.washingtonpost.com/national/health-science/how-much-to-worry-about-the-radiation-from-ct-scans/2016/01/04/8dfb80cc-8a30-11e5-be39-0034bb576eee_story.html. Accessed October 30, 2019.
  2. Vaiserman A, Koliada A, Zabuga O, et al. Health Impacts of Low-Dose Ionizing Radiation: Current Scientific Debates and Regulatory Issues. Dose Response. 2018 Jul-Sep;16(3):1559325818796331.
  3. Available at: https://www.sciencedaily.com/releases/2017/06/170607123926.htm. Accessed November 6, 2019.
  4. Lin EC. Radiation risk from medical imaging. Mayo Clin Proc. 2010 Dec;85(12):1142-6; quiz 6.
  5. Available at: https://ratical.org/radiation/CNR/CNRtitles.html. Accessed November 6, 2019.
  6. Available at: https://www.consumerreports.org/cro/magazine/2015/01/the-surprising-dangers-of-ct-sans-and-x-rays/index.htm. Accessed October 30, 2019.
  7. Available at: https://khn.org/news/heavy-use-of-ct-scans-raises-concerns-about-patients-exposure-to-radiation/. Accessed October 30, 2019.
  8. Available at: https://www.lifeextension.com/Magazine/2005/10/awsi. Accessed November 6, 2019.
  9. Available at: https://www.lifeextension.com/magazine/2001/11/report_radiation. Accessed November 6, 2019.
  10. Available at: https://www.lifeextension.com/magazine/2010/8/Lethal-Danger-of-CT-Scans. Accessed November 6, 2019.
  11. Baselet B, Sonveaux P, Baatout S, et al. Pathological effects of ionizing radiation: endothelial activation and dysfunction. Cell Mol Life Sci. 2019 Feb;76(4):699-728.
  12. Lafargue A, Degorre C, Corre I, et al. Ionizing radiation induces long-term senescence in endothelial cells through mitochondrial respiratory complex II dysfunction and superoxide generation. Free Radic Biol Med. 2017 Jul;108:750-9.
  13. Wang Y, Boerma M, Zhou D. Ionizing Radiation-Induced Endothelial Cell Senescence and Cardiovascular Diseases. Radiat Res. 2016 Aug;186(2):153-61.
  14. Fournier C, Zahnreich S, Kraft D, et al. The fate of a normal human cell traversed by a single charged particle. Sci Rep. 2012;2:643.
  15. Available at: https://www.who.int/news-room/fact-sheets/detail/ionizing-radiation-health-effects-and-protective-measures. Accessed October 30, 2019.
  16. Shi L, Tashiro S. Estimation of the effects of medical diagnostic radiation exposure based on DNA damage. J Radiat Res. 2018 Apr 1;59(suppl_2):ii121-ii9.
  17. Maier P, Hartmann L, Wenz F, et al. Cellular Pathways in Response to Ionizing Radiation and Their Targetability for Tumor Radiosensitization. Int J Mol Sci. 2016 Jan 14;17(1):102.
  18. Bussian TJ, Aziz A, Meyer CF, et al. Clearance of senescent glial cells prevents tau-dependent pathology and cognitive decline. Nature. 2018 Oct;562(7728): 578-82.
  19. Kirkland JL, Tchkonia T. Cellular Senescence: A Translational Perspective. EBioMedicine. 2017 Jul;21:21-8.
  20. Xu M, Pirtskhalava T, Farr JN, et al. Senolytics improve physical function and increase lifespan in old age. Nat Med. 2018 Aug;24(8):1246-56.
  21. Available at: https://www.ncbi.nlm.nih.gov/books/NBK57148/. Accessed October 28, 2019.
  22. Azzam EI, Jay-Gerin JP, Pain D. Ionizing radiation-induced metabolic oxidative stress and prolonged cell injury. Cancer Lett. 2012 Dec 31;327(1-2):48-60.
  23. Yentrapalli R, Azimzadeh O, Sriharshan A, et al. The PI3K/Akt/mTOR pathway is implicated in the premature senescence of primary human endothelial cells exposed to chronic radiation. PLoS One. 2013;8(8):e70024.