Sunlight Exposure Reduces Risk of Non-Hodgkin’s Lymphoma, Study Finds

People with high exposure to sunlight or ultraviolet radiation are significantly less likely to develop non-Hodgkin’s lymphoma compared to those with low exposure, but vitamin D levels in the body have no impact on disease incidence, a new study shows.

The study, “Vitamin D status and risk of non-Hodgkin lymphoma: An updated meta-analysis,” was published in the journal PloS ONE.

The incidence of non-Hodgkin’s lymphoma (NHL) — one of the most common blood cancers — has been increasing in the last decade, underscoring the importance of environmental factors in its development.

One of the environmental factors that previously has been shown to be important in NHL is vitamin D. This is especially important as vitamin D deficiency has become a pandemic.

Vitamin D can be acquired a number of different ways. The most common method is through exposure to sunlight or ambient ultraviolet radiation (UVR), but vitamin D pills may also be used.

Prior studies have shown that sunlight exposure has a protective role on the incidence of NHL and its subtypes, but have failed to show an association between dietary vitamin D or the levels of its circulating form 25-hydroxyvitamin D (25(OH)D).

Because of the progress that has been made in the classification and diagnosis of NHL, as well as the persistent emphasis on the vitamin D-NHL association, researchers conducted a meta-analysis of published studies to determine the association between vitamin D status and the risk of NHL and all traceable subtypes.

The goal was to extensively investigate the association between NHL and various measures of vitamin D, including sunlight/UVR exposure, dietary vitamin D intake, and serum  25(OH)D levels.

Researchers reviewed data from 30 studies, including 56,458 NHL patients. Twenty-four studies investigated the impact of sunlight/UVR exposure, nine examined dietary vitamin D intake, and three looked at serum/plasma 25(OH)D levels.

As previously shown, results indicated a significant protective effect of overall sunlight/UVR exposure on NHL and all its subtypes, with a 20% lower risk among patients with high exposure compared to those with low exposure.

In contrast, neither dietary vitamin D intake nor serum/plasma 25(OH)D levels had consistent or significant effects on the risk for NHL or any of its subtypes.

“A consistent protective effect of sunlight/UVR exposure on NHL and the various subtypes was observed, while inconsistent or non-significant association was found for dietary vitamin D intake and serum/plasma 25(OH)D levels,” researchers concluded.