For many years, we have been told to avoid prolonged exposure to the sun because of health risks like sunburn and, more seriously, skin cancer. Now a new study found that getting too little sun can cause problems as well. According to recent research, women who consistently avoided direct sunlight had a greater mortality risk from all causes, including skin cancer, than their counterparts with higher sun exposure.
Sunlight is the main source of vitamin D. Deficiencies in this vitamin are linked to multiple health threats, among them cardiovascular disease and aggressive types of skin cancer, the scientists involved in the study said.
The findings, which were published in the Journal of Internal Medicine, run contrary to recommendations by most experts. Excessive sun exposure is a known cause of skin cancer, which is now the most common form of all cancers, according to the Cleveland Clinic. The Centers for Disease Control and Prevention (CDC) urge people to take preventive measures such as wearing protective clothing and sunscreen to avoid skin damage at all times.
While the authors of this latest study acknowledge the importance of protecting the skin, they say that the established guidelines may be too restrictive, especially in regions of the northern hemisphere where sunshine is limited. In populations living in these areas, there is epidemiological evidence that all-cause mortality is related to low vitamin D levels, the researchers concluded.
For the study, nearly 30,000 Swedish women, ages 25 to 64, were recruited from 1990 for a 20-year follow-up period where their sun exposure habits were recorded and analyzed in connection with their overall health. At the end of the study, 2545 participants had died.
“We have found that all-cause mortality was inversely related to sun exposure habits,” wrote Pelle G. Linqvist, a researcher at the Department of Obstetrics and Gynecology, Cintec, Karolinska University Hospital in Stockholm, Sweden, and lead author of the study report. “The mortality rate amongst avoiders of sun exposure was approximately twofold higher compared with the highest sun exposure group. […] Following sun exposure advice that is very restrictive in countries with low solar intensity might in fact be harmful to women’s health,” she added.
The caveat here is that the study only involved women from Sweden who were presumably of light skin color. The amount of sun exposure each individual received was self-reported, and no blood samples for the determination of vitamin D levels, or information about the use of vitamin D supplements were collected.
Other experts have suggested that the importance of sun exposure as a vitamin D source has diminished due to fortification of many foods we consume today, including dairy products. Also, using supplements can make up for some deficiencies that may result from staying indoors or living in places with fewer sunny days.