Researchers Test Vitamin D Production From Tanning Beds

After finding that vitamin D deficiency was common among elderly people during non-summer days, researchers at the University of Boston decided to see if exposure to UV rays from a commercial tanning bed could effectively stimulate production of this essential vitamin.

The first part of the study, led by Michael Holick, M.D., focused on 45 nursing home residents whose rate of 25(OH)D deficiency raised to 49 percent in August, 67 percent in November, 74 percent in February and 78 percent in May—despite the fact that participants took a vitamin D supplement containing 400 IU of vitamin D2 during the study.

For the second portion of the study, Holick and colleagues exposed 15 healthy adults aged 20 to 53 to UV rays from a commercial tanning bed three times per week for seven weeks and determined their 25(OH)D level on a weekly basis. The tanning bed emitted 5 percent of its UV energy in the UVB range 290 nm to 320 nm. Results from the study showed that exposure to tanning bed irradiation increased pre-vitamin D at a linear rate of 1 percent per minute. One week of exposure led to an increase in 25(OH)D by 50 percent, and five weeks of exposure increased the level by 150 percent. During the last two weeks, 25(OH)D leveled off.

“Vitamin D deficiency is common in both children and adults worldwide,” Holick says. "Exposure to lamps that emit UVB radiation is an excellent way to produce vitamin D3 in the skin and is especially efficacious in patients with fat malabsorption syndromes.”

The current recommended daily allowance for vitamin D is 400 IU for adults, which many experts now believe is too low.  According to the researchers, those experts would recommend 1,000 IU per day as the minimum daily intake.

The study was funded in part by the National Institutes of Health and the Ultraviolet Light Foundation and will be published in the March 2008 issue of the Journal of Bone and Mineral Research.