ACCORDING to news reports being widely circulated in social media, a study published this month in the Journal of Internal Medicine purportedly found that avoidance of exposure to the sun is “as dangerous as smoking,” due to a deficiency of vitamin D3.
Vitamin D3, important to human health, is produced in the body when the skin is exposed to solar radiation. It is also present in many foods, particularly milk. Research has associated a lack of vitamin D with increased risks of certain kinds of cancer, asthma, diabetes, cardiovascular disease, and possibly some autoimmune disorders such as multiple sclerosis.
Mothers in the Philippines and other Asian countries will often expose their newborn babies to morning sunlight to help activate their bodies’ vitamin D production.
One article turning up in social media feeds entitled, “New Study Shows Avoiding Sun Exposure Is As Dangerous As Smoking.” It appeared on the natural health website GreenMed Info and was written by Dr Michael Murphy, who stated: “According to a recent study published in the Journal of Internal Medicine, the life expectancy of people that avoided sun exposure was reduced by about 2 years compared to those who regularly sun bathed. In fact, nonsmokers who stayed out of the sun had a life expectancy similar to smokers who had the highest level of sun exposure.” (emphasis in the original)
The article went on to say: “The results showed that women that regularly sun bathed lived longer because they had a lower rate of death [from]cardiovascular disease (CVD) and deaths that were not due to cancer or CVD as compared to those who avoided sun exposure. However, as a result of living longer, these women did have a higher rate of cancer death.
“Because nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, the researchers concluded that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking.”
The article concludes by saying, “It is time we advocate sensible sun exposure instead of complete avoidance. Sunscreens have their place, but we need some sun exposure for our health. And, we also need to regularly check vitamin D3 levels.”
What the study really said
The study being cited, entitled “Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort,” was the second done by some of the researchers who authored it, and was conducted among a group of more than 29,000 women aged 25 to 64 years in southern Sweden, who were part of an earlier study on melanoma—a common form of skin cancer often caused by overexposure to the sun.
In its results, the study stated: “Women with active sun exposure habits were mainly at a lower risk of cardiovascular disease (CVD) and noncancer/non-CVD death as compared to those who avoided sun exposure. As a result of their increased survival, the relative contribution of cancer death increased in these women. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6-2.1 years.”
In the summary conclusion, therefore, the researchers said, “The longer life expectancy amongst women with active sun exposure habits was related to a decrease in CVD and noncancer/non-CVD mortality, causing the relative contribution of death due to cancer to increase.”
Those outcomes were what were reported in the article that GreenMed Info carried. However, in the more detailed conclusion not included with the research paper’s abstract, which is freely accessible online, the researchers made certain important observations that seem to have been overlooked.
First, they noted that the limitations of their study meant that other lifestyle factors could not be ruled out as contributing to the differences in life expectancy, and they noted that the characteristics of their study group—adult women, an overwhelming majority of whom were Caucasian, and all living in a relatively small area of one Scandinavian country—mean that the findings might not be the same for people not fitting that general description.
Finally, the researchers pointed out that the higher death rates from cancer among the longer-lived part of their study group that had more sun exposure were attributable in part to skin cancer in some cases, although they pointed out that determining the prevalence of fatal cancers brought on by melanoma—or actual fatal cases of melanoma, relatively rare though those are—would require further study.
The researchers also stressed that despite their findings showing some sun exposure is beneficial, excessive exposure to the sun is still a proven, serious risk factor for the development of melanoma or other forms of skin cancer, and that people should exercise caution.