Researchers, in a study published in the Journal of Internal Medicine, found that avoiding sun exposure may increase the risk for all-cause mortality in women.

In past blogs, we’ve covered the positive and negative aspects of sun exposure. Safe, moderate sun exposure is the natural and best way to meet your body’s requirements for vitamin D. On the other hand, intense, infrequent sun exposure may increase your risk for malignant melanoma (MM), the most severe form of skin cancer.

In recent decades, a “sun scare” has developed that has led  people to avoid sun exposure because studies showing increased risk of skin cancer due to intense sun exposure have received more public attention than ones showing the benefits of vitamin D and safe, moderate sun exposure.

There has been little research looking at the effects that sun avoidance may have on human health. We know that adequate vitamin D levels can help improve areas such as bone health, the immune system and the heart, but how might complete avoidance of the sun affect our health?

Recently, researchers out of Sweden conducted a study on Northern European women to determine the effects of sun avoidance on health.

The researchers looked at data from the Melanoma in Southern Sweden (MISS) study. The MISS study began in 1990 and included 29,518 women aged 25 to 64 years old. The women answered questions about risk factors for melanoma in 1990 and then again at a follow-ups in 2000 and 2011. The study aimed to compare the women’s viewpoints on risk factors for melanoma with the actual development of cancer and mortality over the 20 year period.

In the current study, the researchers looked at data of all the women from the MISS study who had no previous history of cancer or any malignancy. They looked at questionnaire responses in 1990 and again at the follow-up in 2000.

Among other lifestyle questions, the women were asked to answer four yes-no questions regarding sun exposure habits. To measure total sun exposure, the researchers scored each woman’s response by the number of times that they answered “yes” to these questions.

A score of 0 signified complete sun avoidance and a score of 4 signified the greatest amount of sun exposure.

The researchers wanted to know if avoiding the sun might affect the risk of all-cause mortality among the women.

After all data was collected and analyzed, the researchers found:

• The mortality rate among women who avoided the sun was double compared to those with the highest sun exposure.
• There was a dose-dependent inverse relationship between sun exposure and all-cause mortality. This means that the rate of all-cause mortality decreased with every increase in ratings of sun exposure.

The researchers concluded,

“The mortality rate was increased two-fold among avoiders of sun exposure as compared to those with the highest sun exposure habits. In this study focusing on avoidance of sun exposure, women with ‘normal’ sun exposure habits were not at significantly increased risk for MM or of MM-related death.”

In this study, the researchers looked at women of northern European descent. Many women of this region have light skin, and therefore are more sensitive to the sun. Because the researchers only looked at northern European women, we don’t know if these results would be the same in populations of different gender or ethnicity. Furthermore, the use of a questionnaire means that we don’t know if sun exposure habits were accurately reported by the participants, and due to the observational design of the study, we don’t know for sure if higher sun exposure decreases risk of mortality.

While this study cannot confirm that sun exposure reduces risk of mortality, it is more evidence that safe, moderate sun exposure is an effective way to produce vitamin D and maintain good health.

Source

Lindqvist, P. et al. Avoidance of sun exposure is a risk factor for all-cause mortality: results from the MISS cohort. Journal of Internal Medicine, 2014.