Benefits of Sunlight: A Bright Spot for Human Health 2

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Part 2 of “The Benefits of Sunlight: Vitamin D Production” by M. Nathaniel Mead focuses on the importance of getting sufficient Vitamin D from sunlight and food sources.  Vitamin D is necessary for human health.  Learn how  Vitamin D is used by the body to build stronger bones and increase immunity.

Benefits of Sunlight: A Bright Spot for Human Health

M. Nathaniel Mead
Vitamin D Production

Unlike other essential vitamins, which must be obtained from food, vitamin D can be synthesized in the skin through a photosynthetic reaction triggered by exposure to UVB radiation. The efficiency of production depends on the number of UVB photons that penetrate the skin, a process that can be curtailed by clothing, excess body fat, sunscreen, and the skin pigment melanin. For most white people, a half-hour in the summer sun in a bathing suit can initiate the release of 50,000 IU (1.25 mg) vitamin D into the circulation within 24 hours of exposure; this same amount of exposure yields 20,000–30,000 IU in tanned individuals and 8,000–10,000 IU in dark-skinned people.

The initial photosynthesis produces vitamin D3, most of which undergoes additional transformations, starting with the production of 25-hydroxyvitamin D (25[OH]D), the major form of vitamin D circulating in the bloodstream and the form that is routinely measured to determine a person’s vitamin D status. Although various cell types within the skin can carry out this transformation locally, the conversion takes place primarily in the liver. Another set of transformations occurs in the kidney and other tissues, forming 1,25(OH)D. This form of the vitamin is actually a hormone, chemically akin to the steroid hormones.

1,25(OH)D accumulates in cell nuclei of the intestine, where it enhances calcium and phosphorus absorption, controlling the flow of calcium into and out of bones to regulate bone-calcium metabolism. Michael Holick, a medical professor and director of the Bone Health Care Clinic at Boston University Medical Center, says, “The primary physiologic function of vitamin D is to maintain serum calcium and phosphorous levels within the normal physiologic range to support most metabolic functions, neuromuscular transmission, and bone mineralization.”

Without sufficient vitamin D, bones will not form properly. In children, this causes rickets, a disease characterized by growth retardation and various skeletal deformities, including the hallmark bowed legs. More recently, there has been a growing appreciation for vitamin D’s impact on bone health in adults. In August 2007, the Agency for Health Care Policy and Research published Effectiveness and Safety of Vitamin D in Relation to Bone Health, a systematic review of 167 studies that found “fair evidence” of an association between circulating 25(OH)D concentrations and either increased bone-mineral density or reduced falls in older people (a result of strengthened muscles as well as strengthened bones). “Low vitamin D levels will precipitate and exacerbate osteoporosis in both men and women and cause the painful bone disease osteomalacia,” says Holick.



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This entry was posted on Sunday, January 28th, 2024 at 4:50 am and is filed under Articles.

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One Comment

tltandr said:

on October 9th, 2009

How the skin can produce VITAMIN D??????
Biophoton from our Mother SUN during SUNGAZING in the mornong hours of SUNRISE BUT NOT EXSEEDING 7 a.m. and by reflection of our surrounding during daytime sun rays where sunbiophoton entering our eyes, and ACTIVATING OUR DNA TO PRODUCE VITAMIN D

DR TAN tjiuaw liat


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