Vitamin D/Pancreatic Cancer Link Illuminated
Do you live in the Northern Hemisphere? Is it often cloudy where you live? If so, you’re accustomed to experiencing progressively shorter hours of daylight in the fall and winter. At the same time, your skin’s ability to generate vitamin D, with the help of the sun’s ultraviolet radiation, quickly falls and then stops completely in winter. Accordingly, people who live at higher latitudes tend to have low levels of vitamin D circulating in their bloodstreams during the cold, gray months of fall and winter.
In recent decades, it’s become increasingly clear that vitamin D plays an enormous role in regulating immunity, among other functions. Scientists have begun to pay attention to these oscillations in levels of natural vitamin D, and have begun comparing them with rising and falling risks for various diseases. Could falling vitamin D levels be linked to the likelihood that one will develop diseases such as multiple sclerosis, influenza, or even pancreatic cancer? The answer may be yes, at least in some instances.
Maps that show ultraviolet levels at various latitudes, compared with maps showing the prevalence of various diseases, suggest a relationship between these two factors. Previous research has noted a link between the risk that a person will be diagnosed with the neurological disorder, multiple sclerosis, and the latitude at which a person lives. To be sure, people who live in northern latitudes—as opposed to tropical latitudes—are significantly more likely to contract multiple sclerosis. Of course, correlation does not prove causation. But experts agree that low seasonal vitamin D levels undoubtedly play a role in MS risk. The increased risk is probably due to alterations in immune system function due to falling vitamin D levels.
Now investigators have noted a similar association between seasonally low vitamin D levels and the risk of being diagnosed with pancreatic cancer. That’s alarming, because pancreatic cancer remains one of the most feared, and deadly, of all cancers. Most patients die within 5 years of diagnosis, and few treatments are available that appear to make much of a difference in the course of the disease.
"People who live in sunny countries near the equator have only one-sixth of the age-adjusted incidence rate of pancreatic cancer as those who live far from it. The importance of sunlight deficiency strongly suggests—but does not prove—that vitamin D deficiency may contribute to risk of pancreatic cancer,” said first author Cedric F. Garland, DrPH, in a new report published in the Journal of Steroid Chemistry and Molecular Biology.
In a previous report, Garland and other vitamin D experts noted recently that the Institute of Medicine, which sets standards for nutrients that are recommended by the U.S. government, made a mathematical error when computing the daily requirements for vitamin D. Rather than aiming to consume about 600 IU from all sources, say the investigators, people should be getting about ten times that much—or about 7,000 IU vitamin D3 daily. "This intake is well below the upper level intake specified by IOM as safe for teens and adults, 10,000 IU/day," Garland said.
Cedric F. Garland, Raphael E. Cuomo, Edward D. Gorham, Kenneth Zeng, Sharif B. Mohr. Cloud cover-adjusted ultraviolet B irradiance and pancreatic cancer incidence in 172 countries. The Journal of Steroid Biochemistry and Molecular Biology, 2015; DOI: 10.1016/j.jsbmb.2015.04.004
Paul Veugelers, John Ekwaru. A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients, 2014; 6 (10): 4472 DOI: 10.3390/nu6104472