Ask most people what they fear most and the answer is almost always cancer. That’s because cancer rivals heart disease as our number one killer. We now have highly effective treatments for heart disease and even if people experience a heart attack, doctors can frequently intervene to save their lives. Cancer, on the other hand, is still mysterious. Skin cancer is especially challenging. We have all been told that we can reduce our risk dramatically if we just slop on the sunscreen and/or avoid sunlight. Why is skin cancer continuing to increase?
The Evolution of Sunscreens vs. Sunlight:
Do you like medical mysteries? We find them fascinating. Most dermatologists would prefer not to address this one.
If you are as old as we are you may remember the day when there were no SPF (sun protection factor) sunscreens. An old Coppertone ad featured a little girl with pig tails and a dog pulling down her bathing suit. Her butt was white but the rest of her body was tanned. Some of these original tanning lotions contained cocoa butter and coconut oil. They did not block out ultraviolet rays.
If lifeguards wanted to avoid burning their noses every day, they had to smear them with very white zinc oxide cream. It was the only effective protection against sunlight’s damaging UV radiation. But it was cosmetically unappealing. The white-nose look may have worked, but it was unappealing.
Before 1974 creams and lotions could not advertise an SPF number. But Sunscreens have improved dramatically over the last 50 years. We have seen a proliferation of sunscreen products providing SPF levels of 50 or higher. There are even products with an SPF of 100. People can spend all day in the sun without getting burned or even tanned.
Are Sunscreens Preventing Cancer and Saving Lives?
The mystery is that skin cancer has been increasing despite the widespread availability of highly effective sunscreens. Both basal and squamous cell carcinomas have been going up. More alarming, the rate of potentially life-threatening melanoma has also been rising rapidly over the last several decades despite increasing use of highly effective sunscreens.
There are lots of hypotheses to explain this inconsistency. Some experts have proposed that using sunscreen may give people a false sense of protection against sunlight and damaging UV radiation. People may just spend way too much time outside, especially during the middle of the day.
Dermatologists frequently assert that people do not use enough sunscreen to protect their skin. We hear that one a lot! It’s unlikely that people are using less sunscreen these days then they were 30 years ago, though.
Other scientists point to a depletion of the ozone layer which allows more ultraviolet (UV) sunlight to get through the earth’s atmosphere. At the end of the day, though, leading dermatologists admit that the data are perplexing (Cancers, Dec. 2023).
There is something even more challenging for American dermatologists. A recognition is growing abroad that some sun exposure may be beneficial. That seems like an oxymoron and contradicts the position of the American Academy of Dermatology (AAD).
Avoid Sunlight or Slather on the Sunscreen!
The AAD recommends no sun exposure. Everyone must use highly effective sunscreen, stay out of direct sunlight between 10 a.m. and 2 p.m. and wear sun-protective clothing at other times of day.
To make up for a lack of sun exposure that could lead to vitamin D deficiency, patients are advised to take vitamin D supplements. But how helpful are vitamin D supplements really?
Bursting the Vitamin D Bubble:
The trouble is that a study in the New England Journal of Medicine (July 28, 2022) demonstrated that vitamin D supplements did not reduce the risk of fractures. An editorial in the same issue pointed out:
“…vitamin D supplementation did not prevent cancer or cardiovascular disease, prevent falls, improve cognitive function, reduce atrial fibrillation, change body composition, reduce migraine frequency, improve stroke outcomes, decrease age-related macular degeneration, or reduce knee pain” (NEJM, July 28, 2022).”
This is certainly a disappointment, but not a big surprise. It is consistent with other randomized controlled trials of vitamin D supplementation.
Can Some Sunlight Be Beneficial?
A group of Australian public health experts have taken a step away from the complete sun avoidance camp. It has issued some new guidelines for cautious, customized time outdoors in a white paper titled, “Balancing the Harms and Benefits of Sun Exposure.”
Acknowledging that skin cancer prevention must remain a high priority, the authors continue, “completely avoiding sun exposure is not optimal for health.” There are, for example, data that suggest some UV light exposure helps control inflammation and an overactive immune system.
Some American dermatologists may find this position difficult to accept. It would mean crafting a more complex public health message and taking more time with each patient to discuss whether and when to allow a little bit of sun exposure.
Is Vitamin D Helpful for Cancer Prevention?
Preventing cancer and prolonging life after a diagnosis is the primary goal. Could vitamin D provide an important element in an anticancer strategy? There is growing evidence that the sunshine vitamin might play a far more important role in both cancer prevention and survival than most people realize.
What Does Sunlight Have to Do with Cancer?
Vitamin D is made by human skin when it is exposed to sunlight. Epidemiologists have known for a long time that people who live in areas where there is a lot of sunshine have a lower likelihood of coming down with cancer and people who live in areas of less sunshine have a higher likelihood of developing cancer (Cancer Causes & Control, March, 2005; Anticancer Research, Sept, 2009; Epidemiology and Genomics Research, National Cancer Institute, May 7-8, 2007; BJU International, Nov. 2011).
Evidence is growing that people with adequate vitamin D levels are less likely to be diagnosed with cancer and more likely to survive a cancer that occurs (Dermato-Endocrinology, Apr/May/June, 2012). Women with higher vitamin D levels had better survival after diagnosis with breast cancer (Carcinogenesis, online May 24, 2012).
A large study showed higher vitamin D levels associated with a lower likelihood of lethal prostate cancer (Journal of the National Cancer Institute, May 2, 2012). One protocol showed benefit for men with prostate cancer taking 4000 IU of vitamin D3 daily (Journal of Clinical Endocrinology and Metabolism, online Apr. 16, 2012). This dose is high, so no one should undertake such a dose without medical supervision!
More recent research is beginning to clarify how vitamin D fights cancer. It inhibits the stem cells that give rise to cancer and pushes cells to differentiate (Journal of Steroid Biochemistry and Molecular Biology, online Dec. 3, 2016). When cells differentiate, they are far less likely to become out-of-control tumor cells. In addition, the vitamin D receptor is crucial in preventing inflammatory bowel disease and colon cancer (Current Medicinal Chemistry, online Dec. 2, 2016).
Sunlight or Pills?
Which is better, sunlight or vitamin D3 pills? This is a highly controversial topic, and there isn’t good evidence currently available to answer this question. Some vitamin D experts believe that 10 to 15 minutes of sun exposure three or four times a week is the best solution to the vitamin D dilemma. As mentioned above, most dermatologists believe that going out in the sun without a high SPF sunscreen is just plain dangerous.
Dutch scientists have pointed out that sunlight may go beyond providing adequate vitamin D (Medical Hypotheses, Dec., 2016). In addition, sunlight affects our natural clocks (circadian rhythm), and through that has an impact on the immune system. They point out that in Europe people with intermittent sun exposure are more prone to the deadly skin cancer melanoma, while those with more regular exposure are at lower risk.
Symptoms of Vitamin D Deficiency
- Asthma
- Fatigue
- Fractures
- Insomnia
- Joint aches
- Mood swings
- Muscle pain
To read more about testing for vitamin D levels (and what is now considered prudent), the safest dosing range, preferable vitamin D formulations, and a variety of other practical you may wish to check out our Guide to Vitamin D Deficiency.
Meanwhile, make sure you are getting the right amount of sun or the optimal amount of vitamin D from a supplement. It just might save your life! Please share your own thoughts about sunlight in the comment section below.
