Study shows effects of vitamin D and skin's physiology

Researchers from Boston University School of Medicine (BUSM) have found that previtamin D3 production varies depending on several factors including skin type and weather conditions. The study will appear in the March 2008 issue of the Journal of Bone and Mineral Research.

Excessive exposure to sunlight does not result in Vitamin D intoxification because previtamin D3 and vitamin D3 are photolyzed to several photoproducts. During the winter at altitudes above ~35 degrees, there is minimal if any previtamin D3 production in the skin. Increased skin pigmentation, application of a sunscreen, aging and clothing have a dramatic effect on previtamin D3 production in the skin. It has been speculated that people living at higher altitudes may be able to more efficiently produce vitamin D3 in their skin because there is less ozone to absorb the UVB photons.

Forty-five nursing home residents who were taking a multivitamin that contained 400 IU of vitamin D2 showed a dramatic decline in their 25(OH)D levels from the end of summer to the beginning of the following summer. Forty-nine percent, 67 percent, 74 percent, and 78 percent of the nursing home residents were vitamin D deficient in August, November, February, and May respectively.

Fifteen healthy adults aged 20-53 received exposure three times per week from a commercial tanning bed that emitted five percent of its UV energy in the UVB range 290-320 nm to most of their body while in a bathing suit. 25(OH)D levels were determined weekly for a total of seven weeks.

Exposure of 7-dehydrocholesterol to tanning bed irradiation revealed -1 percent production of previtamin D after one minute and a linear increase to -10 percent at 10 minutes. After one week, there was a 50 percent increase in 25 (OH)D levels that continued to increase over a period of five weeks to -150 percent above baseline levels. The blood levels of 25 (OH)D plateaued after five weeks and were sustained out to seven weeks.

“Vitamin D deficiency is common in both children and adults worldwide,” said Michael Holick, PhD, MD, director of the General Clinical Research Center and professor of medicine, physiology and biophysics at BUSM and senior author of this study. “Exposure to lamps that emit UVB radiation is an excellent source for producing vitamin D3 in the skin and is especially efficacious in patients with fat malabsortion syndromes.”

It has been observed that living at higher altitudes and being more prone to vitamin D deficiency markedly increases risk of many deadly cancers including cancer of the colon, prostate, breast, and esophagus, according to Holick, who is also director of the Bone Healthcare Clinic and the vitamin D, Skin and Bone Research Laboratory at Boston University Medical Center. Living at higher altitudes also increase the risk of having hypertension, type I diabetes, multiple sclerosis and other autoimmune diseases, and infectious diseases including tuberculosis and influenza.

According to researchers, most experts now agree that a minimum of 1000 IU of vitamin D3 per day is necessary to maintain circulating concentrations of 25(OH)D.

Source: Boston University

Related stories:

Fortified cassava could provide a day's nutrition in a single meal
Scientists have determined how to fortify the cassava plant, a staple root crop in many developing countries, with enough vitamins, minerals and protein to provide the poor and malnourished with a day's worth of nutrition in a single meal.
Lack of sunshine vitamin may cloud survival odds
(AP) -- New research linking low vitamin D levels with deaths from heart disease and other causes bolsters mounting evidence about the "sunshine" vitamin's role in good health.
Vitamin D: New way to treat heart failure?
Strong bones, a healthy immune system, protection against some types of cancer: Recent studies suggest there's yet another item for the expanding list of vitamin D benefits. Vitamin D, "the sunshine vitamin," keeps the heart, the body's long-distance runner, fit for life's demands.
Get a Little Sun This Summer – It Could Help Save Your Life
As summer comes and people across America get ready to start slathering on the sunscreen, a note of caution is in order – a little sunshine is good for you.
Study links vitamin D, type 1 diabetes
Sun exposure and vitamin D levels may play a strong role in risk of type 1 diabetes in children, according to new findings by researchers at the Moores Cancer Center at University of California, San Diego (UCSD) and the Department of Family and Preventive Medicine. This association comes on the heels of similar research findings by this same group regarding vitamin D levels and several major cancers.
New ballast treatment could protect Great Lakes fish
A Michigan Technological University professor has developed a new water treatment that could help keep a deadly fish disease out of Lake Superior.
Potential therapy discovered for hypophosphatasia, a congenital form of rickets
Researchers at the Burnham Institute for Medical Research, led by José Luis Millán, Ph.D., have demonstrated in mice the first successful use of enzyme replacement therapy to prevent hypophosphatasia (HPP), a primary skeletal disease of genetic origin. This discovery lays the foundation for future clinical trials for HPP patients.
Good news for a fast-wrinkling generation: Some anti-aging methods work
Fine wrinkles, deeper creases, saggy areas around the mouth and neck – the sights in the mirror that make baby boomers wince – are not inevitable. They result from a structural breakdown inside the skin that some existing treatments effectively counteract by stimulating the growth of new, youthful collagen, University of Michigan scientists say.

News discussion:

Medicine & Health news