I like it when a paper begins by assuming sunlight and vitamin D both help prevent internal cancers, not just vitamin D. Recently, that is exactly what Dr. Han van der Rhee and colleagues from the Netherlands did in asking an important question, which is better to prevent cancer, sunlight or vitamin D?
They report the following:
- Evidence is quite strong that sunlight prevents colorectal, breast, prostate and lymphoma.
- Most studies of melanoma show that chronic sun exposure decreases the risk of melanoma.
- The association of vitamin D deficiency and cancer is strongest for colorectal cancer.
- Besides vitamin D, sunlight may prevent cancer by regulating the circadian rhythm, the body’s internal clock, as studies show disruption of that clock is associated with cancer.
- Sunlight exposure can increase melatonin secretion at night and melatonin has anti-cancer effects.
- In breast cancer, melatonin increases the sensitivity of cancer cells to the anti-cancer effects of vitamin D.
- Sunlight degrades folic acid in the skin and this may play a role in preventing cancer.
The authors summed up by saying,
“The evidence that chronic (not intermittent) sun exposure decreases the risk of colorectal, breast, prostate cancer and lymphoma is accumulating and gradually getting stronger. We therefore think that, particularly in countries with moderate climate, intermittent sun exposure (and sunburn) should on the one hand be discouraged, because of skin cancer prevention, while on the other hand (moderate) chronic sun exposure possibly should be advised.”
In fact, we believe that avoidance of sunlight and UV is so unnatural, that we recommend sunbathing in the summer and sunbed use in the winter as a natural way of maintaining natural vitamin D levels. Just be sure the sunbed you choose in a suntan parlor is an old-fashioned low-pressure sunbed.