The controversial study, published in the March edition of the Journal of Thrombosis and Haemostasis, and widely reported in international media, claims that extensive suntanning – including during the hottest part of the day, and in solariums – reduces the risk of developing blood clots by 30 percent.
The study claimed that Vitamin D is produced in the body with increased sun exposure, and it is the resulting high Vitamin D levels that are responsible for reducing the risk of blood clots.
The release of the report has sparked a wave of public interest, with Yvonne Brandberg – professor in care sciences at the department of oncology and pathology at the Karolinska University Hospital in Stockholm, and scientific secretary of the research board at the Swedish Cancer Foundation locking horns on morning television with one of the report’s co-authors, Håkan Olsson, professor of oncology at Lund University Hospital.
Brandberg has dismissed the report’s advice as dangerous: “For all of us involved in this kind of research, this is a very strange thing to say,” Brandberg told The Local.
She said there was clear evidence that extended time in the sun and in solariums is a risk factor for malignant melanoma, the most dangerous form of skin cancer, especially extensive suntanning and exposure that results in burning.
“It’s amazing they can make these claims,” Brandberg added.
Brandberg criticised the methodology of the study on a number of levels, suggesting that it failed to adequately control for healthy lifestyle choices of women who spend a lot of time out in the sun.
“I think the reason for the findings is that these women were behaving more healthily than those who didn’t sunbathe, and that’s the reason they found a lower risk of thrombosis in these women,” Brandberg said. The link made in the study between the subjects’ Vitamin D levels and their levels of sun exposure was also purely speculative, she added.
See also: Staying safe in the Swedish sun