Sunlight, a cancer drug?

 

At the age of 18, I believed the healthiest choice was to avoid the sun almost entirely. I wore sunscreen everyday, reapplied it religiously, stayed in the shade;it felt responsible at the time. Years later, a routine blood test showed I had developed a vitamin D deficiency. Not long after, I came across this video on Youtube of a young Japanese woman whose situation was even more intense. She had taken sun protection to an extreme level, avoiding sunlight almost entirely, and eventually developed five spinal fractures due to severe low bone density. Doctors mentioned her bone density resembled that of someone with osteoporosis, despite her being 26. Her story didn’t surprise me. Without adequate sunlight, the body can’t properly synthesize vitamin D, which is crucial for bone health, immune function, and proper cell regulation. 

What surprised me the most was learning that vitamin D may play a role in lowering the risk of cancer. Researchers have found that higher blood levels of vitamin D are associated with reduced incidence of several cancers including breast, prostate, and colorectal cancers (Garland et al, 2006), This is due to vitamin D’s ability to reduce abnormal cell differentiation, promote apoptosis in certain malignant cells, and restrain the formation of new blood vessels that feed cancer (Feldman et al, 2014). 

This doesn’t mean unlimited sun exposure is harmless, as we already know excessive UV exposure is linked to skin cancer. However, other studies showed that regions with higher sunlight exposure tend to have lower rates of several cancers, and this is attributed to greater vitamin D synthesis (Grant et al, 2009). 

This made me rethink my relationship with the sun. Like most things in life, it’s about balance. People often talk about the dangers of too much sun, but we rarely talk about how too little sun can also affect our health in ways that aren’t obvious until later. 

References 

Garland, C. F., Garland, F. C., Gorham, E. D., Lipkin, M., Newmark, H., Mohr, S. B., & Holick, M. F. (2006). The role of vitamin D in cancer prevention. American Journal of Public Health, 96(2), 252–261. https://doi.org/10.2105/AJPH.2004.045260

Feldman, D., Krishnan, A. V., Swami, S., Giovannucci, E., & Feldman, B. J. (2014). The role of vitamin D in reducing cancer risk and progression. Nature Reviews Cancer, 14(5), 342–357. https://doi.org/10.1038/nrc3691

Grant, W. B., & Mohr, S. B. (2009). Ecological studies of ultraviolet B, vitamin D, and cancer since 2000. Anticancer Research, 29(9), 3495–3506.