Does Indoor Tanning Produce Vitamin D?
For years Dr. Michael Holick, director of the General Clinical Research Center
at the Boston University School of Medicine, has talked about the theory of
"Vitamin D Winter" - a term he coined describing the fact that there is not
sufficient UVB outdoors from November through March in the Northeast for a
person to even produce vitamin D. This may explain why so much of the
population is vitamin D deficient.
Dr. Holick's work in the mid 1990s showed that there is no reliable source of
vitamin D in our diets, that vitamin D levels reported on milk cartons are
overestimated half of the time and that 15-20 percent of milk has no vitamin D
content at all. That leaves sun exposure and vitamin supplementation as the
only alternatives. Since it is not reasonable to assume that the entire
population will turn to vitamin supplementation, that puts sunshine back into
play as an important source of this important vitamin. "With adequate exposure
to sunlight, dietary vitamin D becomes unnecessary, according to Holick in an
article he wrote in The Lancet, " It is remarkable how exposure to sunlight a
few times a week can reduce the risk of osteoporosis, osteomalacia, muscle
weakness, fractures and maybe some of the common cancers, but also induce a
sense of well-being."
Sunlight is proving to be the most reliable source of vitamin D, but does a
tanning unit provide the same benefit? In 1998, Holick published a paper in the
medical journal The Lancet showing that 41 percent of hospital patients at
Massachusetts General Hospital were vitamin D deficient. Since that time, with
funding from ITA (International Tanning Association) and The International
Smart Tan Network, Holick has compiled data on another group of chronically
unexposed people: his own medical students, whose studies leave them little
time outdoors at all. "These are people who never see the light of day," Holick
explained. Sure enough, 41 percent of his medical students were vitamin D
deficient. But, upon exposure to the tanning beds in Holick's lab, the
condition was corrected. Holick plans to publish a paper on this data in the
near future. "It will show that indoor tanning is a very effective way to
maintain your vitamin D status," Holick said.
Dr. Holick also believes there may be a link between melanin production and
vitamin D production. Using a flash spectrometer Holick was able to "measure"
and chart the progress of the medical students' tans. Two hours after tanning,
the group showed immediate pigment darkening - a 2-3 percent increase in
pigmentation. Within 48 hours, melanin content increased up to 40 percent.
Holick believes This data will help him explore that theory.