Can tanning beds or sunlight produce sufficient vitamin D to produce superbly strong bones? The answer appears to be “yes.”
I am part of an email list of persons who are intensely interested in vitamin D research and who share articles on vitamin D and sunlight as preventive therapies for various diseases. I recently received a most interesting email from Rufus Greenbaum, who lives in the UK and who organizes vitamin D symposiums there. He had met a man who had been using a tanning bed twice weekly since 1970 and who had just completed a bone densitometer test, known as a DEXA scan. On viewing the results of the scan, his doctor told him “You have the strongest bones that I have ever seen.”
That news certainly came as no shock. Conventional tanning beds produce vast quantities of vitamin D in short periods of time, and vitamin D is absolutely essential for optimal absorption of calcium in the gut.  Without calcium absorption, vast quantities of ingested calcium will make little difference to bone strength; much of the calcium will be passed through the intestine and flushed down the toilet. It is already known that people who use tanning beds have dramatically stronger bones and higher blood-vitamin D levels than those who don’t use them.
Both tanning beds and sunlight enhance the levels of vitamin D in the skin by producing UVB light, which converts cholesterol in the skin to vitamin D. In fact, ninety percent of the vitamin D produced in the US population is due to sunlight exposure.
Research has shown that daily sunlight exposure in elderly women, during a period of one year, increased serum vitamin D levels by 400% and decreased the risk of hip fractures dramatically. A control group, who did not receive sunlight exposure, had six fractures for each fracture experienced by the sunlight-exposed group. The message is that sunlight exposure may decrease the risk of osteoporotic fractures by 84%! Finally, and even more impressively, research from Spain showed that among women who actively sought the sunlight, the risk of fractures was only one-eleventh that of women who spent most of their lives indoors. This begs the questions: Should we really avoid sunlight and tanning beds like the plague? Is such avoidance worth the risk of dying from osteoporotic fractures?
The key to safe exposure to sunlight or sunlamps is to be sure not to burn. And for those who are frightened about melanoma, please read my previous blogs on the subjects: http://drsorenson.blogspot.com/2010/07/exposing-melanoma-fraud-part-1.html
 Grant, W. Personal communication with the author, June, 2006
 Heaney, R. et al. Calcium Absorption Varies within the Reference Range for Serum 25-Hydroxyvitamin D. Journal of the American College of Nutrition 2003; 22: 142–146.
 Heaney, R. Vitamin D and calcium interactions: functional outcomes. Am J Clin Nutr 2008;88(suppl):541S–4S
[4 Tangpricha V. et al. Tanning is associated with optimal vitamin D status (serum 25-hydroxyvitamin D concentration) and higher bone mineral density. Am J Clin Nutr 2004;80:1645-49.
 Reichrath J. The challenge resulting from positive and negative effects of sunlight: how much solar UV exposure is appropriate to balance between risks of vitamin D deficiency and skin cancer? Prog Biophys Mol Biol 2006;92(1):9-16
[6 Sato Y, Metoki N, Iwamoto J, Satoh K. Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure in stroke patients. Neurology 2003;61(3):338-42.
 Larrosa, M. Vitamin D deficiency and related factors in patients with osteoporotic hip fracture. Med Clin (BARC) 2008;130:6-9.