Benefits of Sunlight: A Bright Spot for Human Health 3

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Titled Evolution of the Great Solar Debate, this section of Benefits of Sunlight presents the anthropolical perspective on human development, vitamin D and sunlight.  Learn the biological evolution of humanity as they migrated from high sunlight regions of Africa to lower light regions in Europe.  Learn how the Industrial Revolution in Europe was plagued with rickets due to inadequate sunlight exposure from too much time spent indoors.  Learn how sunlight exposure was used to cure tuberculosis.

Benefits of Sunlight: A Bright Spot for Human Health

M. Nathaniel Mead
Evolution of the Great Solar Debate

In the 2002 book Bone Loss and Osteoporosis in Past Populations: An Anthropological Perspective, Reinhold Vieth, a nutrition professor at the University of Toronto, writes that early primates probably acquired their relatively high vitamin D requirements from frequent grooming and ingestion of oils rich in vitamin D precursors that were secreted by their skin onto their fur. The first humans evolved in equatorial Africa, where the direct angle of sunlight delivers very strong UVR most of the year. The gradual loss of protective fur may have created evolutionary pressure to develop deeply pigmented skin to avoid photodegradation of micronutrients and protect sweat glands from UVR-induced injury.

In the July 2000 issue of the Journal of Human Evolution, California Academy of Sciences anthropologists Nina Jablonski and George Chaplin wrote that because dark skin requires about five to six times more solar exposure than pale skin for equivalent vitamin D photosynthesis, and because the intensity of UVB radiation declines with increasing latitude, one could surmise that skin lightening was an evolutionary adaptation that allowed for optimal survival in low-UVR climes, assuming a traditional diet and outdoor lifestyle. Cooler temperatures in these higher latitudes resulted in the need for more clothing and shelter, further reducing UVR exposure. With shorter winter days and insufficient solar radiation in the UVB wavelengths needed to stimulate vitamin D synthesis, dietary sources such as fatty fish became increasingly important.

Over time, clothing became the norm in higher latitudes and then eventually a social attribute in many societies. By the 1600s, peoples in these regions covered their whole body, even in summertime. Many children who lived in the crowded and polluted industrialized cities of northern Europe developed rickets. By the late 1800s, approximately 90% of all children living in industrialized Europe and North America had some manifestations of the disease, according to estimates based on autopsy studies of the day cited by Holick in the August 2006 Journal of Clinical Investigation and the October 2007 American Journal of Public Health.

Doctors throughout Europe and North America began promoting whole-body sun-bathing to help prevent rickets. It was also recognized that wintertime sunlight in the temperate zone was too feeble to prevent rickets. For this reason, many children were exposed to UVR from a mercury or carbon arc lamp for one hour three times a week, which proved to be an effective preventive measure and treatment.

Around the time the solar solution to rickets gained widespread traction in medical circles, another historic scourge, tuberculosis (TB), was also found to respond to solar intervention. Tuberculosis (TB) patients of all ages were sent to rest in sunny locales and generally returned in good health. Dermatology professor Barbara A. Gilchrest of Boston University School of Medicine says that, whereas sun exposure was shown to improve cutaneous tuberculosis (TB), sanatorium patients with pulmonary tuberculosis (TB) likely responded as much or more to rest and good nutrition than to UVR. Nevertheless, a meta-analysis published in the February 2008 International Journal of Epidemiology found that high vitamin D levels reduce the risk of active tuberculosis (TB) (i.e., TB showing clinical symptoms) by 32%.

Almost overnight, as awareness of the sun’s power against rickets and tuberculosis (TB) spread, attitudes toward sun exposure underwent a radical shift. The suntan became valued in the Western world as a new status symbol that signified both health and wealth, as only the affluent could afford to vacation by the sea and play outdoor sports. Phototherapy quickly emerged as a popular medical treatment not only for tuberculosis (TB), but also for rheumatic disorders, diabetes, gout, chronic ulcers, and wounds. The “healthy tan” was in, and “sickly-looking” pale skin was out.



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This entry was posted on Sunday, May 5th, 2024 at 7:45 am and is filed under Articles.

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One Comment

tltandr said:

on October 10th, 2009

Biophotons activating our whole body DNA.

DR TAN tjiauw liat


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