Dark skin, living in a Northern latitude in winter, avoiding the sun by staying indoors or slathering on sunblock, lowers ultraviolet skin exposure that is necessary to produce vitamin D. But even among populations with intense sunlight and extensive exposures, there are dozens of reports in the biomedical literature of individuals who are still deficient in vitamin D. So parading all of the kids in their bathing suits in the noonday sun will not solve the pandemic of vitamin D deficiency.
Vitamin D Prevents Inflammatory Degenerative Diseases
The list of diseases associated with vitamin D deficiencies is prodigious. Increasing serum levels of vitamin D by adequate supplementation has been reported to reduce the incidence of numerous cancers, cardiovascular disorders, autoimmune diseases and degenerative diseases. In all of these cases, there appears to be a link between vitamin D deficiency, inflammation and disease.
Global Pandemic of Vitamin D Deficiency Despite Adequate Sunlight
Researchers have recently rediscovered that vitamin D deficiency has been increasing for the last several decades. Rickets, accompanied by skeletal and dental deformities is returning, since it first brought the development of Cesarean sections to compensate for the pelvic deformities of the early twentieth century and vitamin D supplementation of milk and other foods. But vitamin D deficiencies are not limited to the Northern latitudes during winter. There are abundant reports of vitamin D deficiencies in populations throughout the world, who are routinely exposed to abundant solar radiation.
Sunlight on Skin (Normally) Produces Copius Vitamin D
Darker skin or cultural covering of skin for modesty, can reduce ultraviolet exposure and vitamin D production, but even under these conditions the production of vitamin D in even a limited area of exposed skin is prodigious. Exposing arms and face to direct sunlight can produce 1,000 IU of vitamin D per minute. Compare that to the recommended daily supplement of 500 IU that has, until recently been used to treat vitamin D deficiency. For many individuals, regardless of skin pigmentation, casual exposure to sun is adequate. Why do others suffer from vitamin D deficiencies that show the symptoms of rickets or increase the risk of degenerative diseases?
Is Rising Chronic Inflammation the Culprit?
One likely candidate is chronic inflammation. As vitamin D deficiencies became more severe during the last three decades, there was a parallel increase in chronic inflammation. Recent studies have shown that low levels of serum vitamin D are associated with high levels of the inflammatory cytokine, tumor necrosis factor-alpha. It is typically thought that vitamin D deficiency is responsible for inflammation. It may also be possible that diet-based chronic inflammation may be compromising the skin’s ability to produce vitamin D in sunlight. This would explain the rise in vitamin D deficiencies in countries with abundant sunlight, but a shift to modern, inflammatory diets.
reference:
Peterson CA, Heffernan ME. Serum tumor necrosis factor-alpha concentrations are negatively correlated with serum 25(OH)D concentrations in healthy women. J Inflamm (Lond). 2008. 5:10.
Join the Conversation