Sunglasses, inscription vitamin D and shape of sun at beach

(© ratmaner -

SAN DIEGO, Calif. — Although sunbathing can potentially be bad for your skin, a new study finds catching enough rays may help lower your risk of one particular type of cancer. Researchers at the University of California-San Diego say a lack of exposure to ultraviolet light can raise someone’s chances of developing colorectal cancer.

In contrast, soaking up the sun increases levels of vitamin D, which protects against the disease. The findings come from a study of cancer cases and mortality rates from across the world. That review discovered individuals in countries that get less sun tend to have higher rates of colon cancer.

“Differences in UVB light accounted for a large amount of the variation we saw in colorectal cancer rates, especially for people over age 45,” says co-author Dr. Raphael Cuomo in a media release.

There are two types of ultraviolet rays that reach the Earth’s surface, UVA and UVB light. Both can cause skin cancer, but UVB is the main source for vitamin D — which strengthens bones, muscles, and even teeth. However, estimates show over four in 10 U.S. adults have a vitamin D deficiency.

“Although this is still preliminary evidence, it may be that older individuals, in particular, may reduce their risk of colorectal cancer by correcting deficiencies in vitamin D,” Dr. Cuomo adds.

Some nations have more trouble getting sun than others

In sunny nations, the study finds the number of cases fell. The phenomenon could lead to simple public health interventions. Light therapies that mimic the benefits of the sun – without the harm – may also be protective.

Unfortunately, there are some drawbacks to getting more sun. Overexposure to UVB rays can cause sunburn and even skin cancer. A protein in the skin converts this light into vitamin D. The nutrient is also believed to stave off breast, prostate, and lung tumors.

Dr. Cuomo and colleagues combined Global Cancer database figures with NASA satellite images of sun-blocking clouds and aerosols. Researchers discovered a “significant link” between less sun and more bowel cancer cases across all age groups. Older people appear to be particularly prone to this connection.

Researchers note their findings take into account other factors including skin pigmentation, life expectancy, and smoking. The United Kingdom, Norway, Denmark, and Canada are examples receiving fewer UVB rays. The United Arab Emirates, Sudan, Nigeria, and India are at the other end of the spectrum.

Dr. Cuomo adds future research could look directly at the potential benefits on colon cancer of correcting vitamin D deficiencies, especially in older age groups. The study in BMC Public Health did not look vitamin D supplements, clothing, and air pollution — which can also effect UVB exposure.

“Further studies are required to assess the need for adequate public health programs such as selective supplementation and food fortification,” researchers write in the study.

Vitamin D is also present in oily fish, egg yolks, cheese, and mushrooms. Colorectal cancer is the third most common cancer in the United States, according to the American Cancer Society.

SWNS writer Mark Waghorn contributed to this report.

Our Editorial Process

StudyFinds publishes digestible, agenda-free, transparent research summaries that are intended to inform the reader as well as stir civil, educated debate. We do not agree nor disagree with any of the studies we post, rather, we encourage our readers to debate the veracity of the findings themselves. All articles published on StudyFinds are vetted by our editors prior to publication and include links back to the source or corresponding journal article, if possible.

Our Editorial Team

Steve Fink


Chris Melore


Sophia Naughton

Associate Editor