New Under the Sun:
Volume 2, Issue 7
Greetings!! Summer is definitely here. Due to the heat during the day, outdoor activities at night may be more appealing. The book reviewed this month may give you a new perspective on star-lit nights; something to think about while you enjoy a glass of lemonade on the patio.
Working the Night Shift Affects Cancer Risk: A Harvard University team using data obtained from 78,562 women enrolled in the Nurses’ Health Study found strong associations between working at night and the development of breast or colon cancers. Nurses who worked a rotating night shift at least three times per month for 15 or more years had a significantly greater risk of developing colon cancer than those who did not work a night shift or had worked such a shift for fewer than 15 years. Those working the rotating night shift for 30 or more years had an increased risk of breast cancer. The researchers concluded that the cause of the increased risks was due to reduced melatonin production. One of the actions of the hormone melatonin is to prevent the growth and spread of cancerous cells. However, light exposure inhibits melatonin production. Therefore, individuals who work at night and who attempt to sleep during the day generally do not have any point during this period when they are in total darkness. In addition, melatonin is regulated by our biological clock with production of the hormone peaking in the middle of the night. Even brief light exposure during the middle of the night can inhibit melatonin production. Night shift workers need to be aware of this and attempt to find a truly dark room for sleeping. E. S. Schernhammer, F. Laden, F. E. Speizer, W. C. Willett, D. J. Hunter, I. Kawachi, C. S. Fuchs, G. A. 2003 Colditz Night-Shift Work and Risk of Colorectal Cancer in the Nurses’ Health Study Journal of the National Cancer Institute. 95 (11): 825-828. E. S. Schernhammer, F. Laden, F. E. Speizer, W. C. Willett, D. J. Hunter, I. Kawachi, G. A. Colditz. 2001 Rotating Night Shifts and Risk of Breast Cancer in Women Participating in the Nurses' Health Study Journal of the National Cancer Institute. 93 (20): 1563-1568.
Comment: While over-exposure to light results in reduced melatonin production and may play a role in the onset of breast and colon cancers, paradoxically, under-exposure to light, specifically UVB radiation, is strongly implicated in the onset of breast, colon, and prostate (something that couldn’t be analyzed in the Nurses’ study) cancers. Exposing unprotected skin to UVB radiation is the first step in the production of vitamin D. Inadequate vitamin D levels in our body have many health implications including increases in the incidences of breast, colon, and prostate cancers. The hormonal form of vitamin D is a tumor suppressant; therefore, inadequate levels would allow tumors to grow unchecked. What the Nurses’ study may actually be showing is that night shift work is problematic on at least two fronts. Due to working at night, melatonin production is depressed. Due to sleeping during the day (avoiding exposure to the sun), vitamin D production is depressed. This combination may provide the trigger to the onset of cancer.
Is Eradication of H. pylori a “Good Thing”?: A previous issue of AnthroHealth News (September, 2002) discussed the health issues associated with H. pylori infection including ulcers, heart disease, and infertility. It now appears that the H. pylori bacterium is on its way to extinction in humans. Good news? Most gastroenterologists would say, “Yes!” However, other researchers are not so certain. Our guts are a complex ecosystem of hundreds (perhaps 500 -1000) of species of bacteria. It may be that at low levels, H. pylori provides some benefits that could be lost by its removal from the micro-ecosystem. The balance of organisms may shift in unexpected ways. There are some indications that the body’s immune response to H. pylori may help prime the immune system to fight other conditions associated with different bacterial pathogens. H. pylori’s dampening effect on stomach acid may also fight esophageal disease. In the United States, we may soon find out whether or not eradication of H. pylori is without unexpected risk since it is fast disappearing from American guts. As Blaser, one of the researchers concerned about eradication points out, "Our indigenous organisms are part of our own physiology. Their extinction may play a role in some of our post-modern diseases." As with so many other things in nature, balance appears to be the key: what is harmful in one individual may provide some benefit to another individual in another environment. J. Whitfield 2003 Gut Reaction. Nature News Service.
Pain: Perception is Reality: Two recent studies have found support for those who say they feel pain more intensely than others do, thus countering those who say that intense sufferers simply do not have a sufficiently stiff upper lip. The first study found actual genetic differences in those who feel pain intensely compared to those who feel only moderate or little pain in the same situation. A gene affecting the modulation of pain called COMT (catechol-O-methyltransferase) has different alleles or variants associated with it. Those individuals who have two copies of the ‘met’ variant feel pain intensely. Those who have two copies of the ‘val’ variant react little to pain, whereas those who have one ‘met’ and one ‘val’ variant are in the middle in their reaction to pain. The val/val individuals have a highly efficient process of breaking down dopamine and noradrenaline. This means that pain receptors are quickly “cleaned up” and the pain signal shut down. On the other hand, the clean up process in met/met individuals is much slower and less efficient with the result that pain signals are activated for a much longer period of time. The majority of individuals have one copy each (val/met) and so have a pain response that is considered “normal”, although it is no more or less normal than are the other two responses. The second study on pain used functional magnetic resonance imaging analysis to show that the brains of those who feel pain intensely clearly react differently and more actively to pain than do the brains of others. There is now objective research to support the subjective perceptions of pain. Given this, medical personnel and others should take seriously what an individual says about his/her pain. Zubieta JK, Heitzeg MM, Smith YR, Bueller JA, Xu K, Xu Y, Koeppe RA, Stohler CS, Goldman D. 2003 COMT val158met genotype affects mu-opioid neurotransmitter responses to a pain stressor. Science 299(5610):1240-3. Coghill RC, McHaffie JG, Yen YF. 2003 Neural correlates of interindividual differences in the subjective experience of pain. Proc Natl Acad Sci U S A. [Epub ahead of print]
Book Review: For those who’ve finished the new Harry Potter, or don’t intend to read it, here is a new book that provides a great summer read: A Short History of Nearly Everything by Bill Bryson. While the title implies a weighty tome (the text length is 478 pages), it reads nearly as quickly as that other ‘weighty tome’: HP & The Order of the Phoenix. Bryson writes in a bright, breezy, very accessible style painting graphic and colorful verbal descriptions of the universe, life, and the scientists who study them. As an example of his writing style, this is from the chapter ‘Welcome to the Solar System’:
Bryson begins with the universe and then brings it down to Earth where we travel through time to the origins of life, finally ending with our own origins. Throughout, he discusses the development of the various fields of scientific endeavor, the major scientific figures in each field, and their idiosyncratic quirks, adding color and life to subject matter that all too often seems boring and dry when studied in school. The text is further enlivened by the inclusion of intriguing tidbits such as noting that when radioactivity was first discovered it was thought to be beneficial (it was natural, after all). Radioactive substances were added to many consumer products until the practice was banned in 1938.
For anyone interested in knowing more about Life, the Universe and Everything (another fun book, by the way), but who prefers to be entertained by their reading during the heat of summer, Bryson has written the ideal book. Grab it and a cool drink and jump on in.
AnthroHealth Tip of the Month: The next clear night in your area, try to find some place distant from city lights. Look up at the starry expanse, admire the patterns the starlight makes, breathe slowly and deeply, and think about the vastness of space and our own small, tiny, miniscule place in that vastness. Although the universe is vast, this world, this Earth, is and will be, our only home. We cannot separate ourselves from nature. We cannot ignore the destruction of nature and expect our lives, our children lives, to go on unchanged. As Chief Seattle once said, “Man did not weave the web of life, he is merely a strand in it. Whatever he does to the web, he does to himself.”
© 2001-2009 Kathleen E. Fuller, PhD. All rights reserved.