Why You Should Ignore Anyone Who Tells You to Have Unsafe Sun this Summer. The Myths about Vitamin D, sunlight and your overall health.
Every once in a while, an article on sunscreen use pops up and I get the dreaded feeling that it’s going to be a popular one. Articles like this recent one from Outside Online, by Rowan Jacobsen, are especially problematic because they are on the surface, pretty persuasive. It’s not the first of its type that I’ve seen and I have the feeling it will become a trend this summer. The problem is that it cherry picks facts throughout history and geography and misconstrues some essentials. The real danger is when parents start making decisions for their young children based on this glib treatment of facts. These decisions can impact their child’s health for their entire life so it’s worth hearing the other side. Here are just a couple of issues with this specific article but also the general argument on a whole:
One of the article's main premise is based on the supposed failure of Vitamin D supplementation vs. the Vitamin D you would get through sunlight exposure. For supplementation to be considered a failure in my mind, it means that it does not replicate the same end product in our bodies that the natural means of sourcing provides. Either your body does not absorb the vitamin properly or gets converted into another end product that is not as beneficial. Entire demographics of people rely on Vitamin D supplementation as their only means of getting it and thus preventing issues with improper calcium absorption and associated diseases like rickets. Breastfed infants rely on it. People of colour also benefit from it as the melanin in their skin prevents ideal absorption from the sun. If Vitamin D supplementation is truly failing then it's something we need to address, not gloss over with a shrug of our shoulders.
The author quotes a recent study from the New England Journal of Medicine suggesting that Vitamin D supplements are a failure. It’s actually a very impressive study in its scope and findings. However, if you take the time to read the whole study and not just the title, you'll see that the Outside Online article misinterprets the findings. The study concludes that Vitamin D supplements failed to prevent incidences of certain forms of cancer and cardiac disease vs. the placebo in their study population. It's been suggested in the past that Vitamin D, in higher doses of 2000 iu or more, could lower your risk of these diseases. The study essentially refutes that. However, it did not compare supplementation from vitamins to naturally sourced Vitamin D (from the sun). Therefore, it’s not a critique of supplementation specifically. It’s a critique of Vitamin D in general. It also clearly discloses that while past observational studies have shown that low levels of Vitamin D in blood correlates with increased risks of cancer and cardiac disease- correlation is not the same as causality. The study’s own introduction suggests that factors like outdoor activity and exercise, someone’s body weight, someone’s diet etc. all may be of import. It acknowledges that it can be easy to make ‘spurious protective associations’ about Vitamin D in general since these other factors were not accounted for in the past.
In short, past studies that saw a correlation between Vitamin D and lower risks of certain diseases may have also been outside more and leading a generally healthier lifestyle, be of a healthy body weight, exercising and eating well. The study did show one silver lining about Vitamin D supplementation- most participants did have an increase in their 25-hydroxyvitamin D levels in their blood after taking the supplements. This means that supplementation worked in terms of getting absorbed and being properly converted. Furthermore, it showed that while it did not lower the overall incidence of cardiac and cancer events, increased levels of Vitamin D did show some improvement in the end outcomes, i.e. less people died from these incidents.
The article has traces of similar forms of rationalization as some anti-vaxxer arguments. Popular opinion has turned recently against the anti-vaxxing argument because people have seen how it involves an over idealization of what is considered a ‘natural’ state and a misunderstanding of scientific facts to the detriment of people’s health. Any argument that begins with any kind of nostalgia about how cavemen used to roam free and lived in this ideal naturalist state should be put on pause. We do not know what types of chronic diseases our early ancestors lived with since we did not have the faculty to diagnose them. More likely than not, most of our ancestors did not have the luxury of having chronic, long term diseases as they had more pressing urgent life crises to deal with, like not getting eaten by a bear. We don’t know what kind of Vitamin D levels our ancestors were getting or not getting and what the impact was on their overall health. Very often, it’s this false sense of nostalgia that leads to the next more dubious part of the argument- that it’s man’s modern scientific inventions, like sunscreen, that have led to their ultimate fall from natural grace.
To be clear- the author does not dispute the benefits of sunscreen in terms of the reduction of skin cancer. He seems to buy the argument that overall sunscreen most likely does help prevent skin cancer. Phew! Except he argues that skin cancer prevention is less critical than the prevention of other cancers or cardiac disease since it has lower death rates than these other diseases. Yikes. He makes the cost/benefit analysis that you should not try to prevent the one with a lower death rate to the detriment of the others. This is again a rather cavalier analysis. If you ask any MOHS surgeon or dermatologist about the impact of skin cancer on a person’s life, they will be the first to tell you it’s more than just a quick visit and having a bad mole removed. Skin cancer can be debilitating, disfiguring and create a sense of anxiety that follows survivors for the rest of their life.
At one point, the article also concedes that Vitamin D from sunlight might not be magic bullet that reduces these diseases but rather that sunlight is providing other unmeasured benefits like in the form of nitric oxide. He cites the work of one dermatologist who exposed patients to 30 mins of sunlight and showed an increase of nitric oxide and a decrease in blood pressure. However, Wells did not compare the 30 mins exposure to other possible means for lowering blood pressure. Laughing- just pure laughter, has been shown to decrease blood pressure by 10 points in 20 minutes.
Both the author and Wells are quite dismissive of alternative methods for preventing cancer and cardiac incidents. Remember- increased Vitamin D levels are only correlated with lowering these diseases. There has been no direct causal link. There are other means for potentially lowering these incidences that do not come with an associated price tag of potentially giving you skin cancer. For example, exercise, meditation improving your diet, losing weight, or simply getting out in nature while still protecting your skin have never been studied against unprotected UV exposure in terms of their impact on these incidences.
The author also makes one very common mistake that we see with increasing frequency and is based on a misunderstanding of how the body even gets Vitamin D from sunlight. We continue to see some ‘experts’ advocate for strategy of getting a light tan, as opposed to a sunburn, in order to ensure they are getting adequate amounts of Vitamin D. This is a fundamental myth that we keep trying to address. Tanning in skin is predominantly associated with UVA exposure. Vitamin D synthesis in the skin from natural sunlight is predominantly associated with UVB light. This means that in order to get something like 2000 iu of Vitamin D from sunlight, someone would need to get a sunburn instead of a tan. When people uses strategies to optimize their tan instead of getting a sunburn, they are actually recreating the experience of sun tanning booths. They are exposing themselves to the long wave UVA rays that penetrate the skin more deeply and have been shown to suppress the body’s immune system and create a cascade of events that lead to DNA mutations leading to skin cancer and photo-aging. Meanwhile, they have not maximized their Vitamin D synthesis.
People of colour with Fitzpatrick skin types 4-6 actually are the best proof of this, despite the authors claims that western medicine is somewhat racist in claiming that everyone should be universally protecting their skin. People of colour have been clinically shown to be less likely to synthesize Vitamin D from sunlight due to the melanin in their skin. Pigment can provide up to a SPF 15. People with darker skin colour therefore have extra protection against sunburns, however they are impacted by the longer wave UVA light to the same degree as people with lighter coloured skin. This is why photo-aging is a problem for people with darker skin tones. However, as mentioned, people of colour do not synthesize Vitamin D from the sun as adeptly as those with lighter skin. The protective nature of their melanin disrupts synthesis of Vitamin D because it protects against UVB and sunburn.
The strategy of getting a tan is a flawed one and one that disproportionately would negatively affect a child versus an adult. There is data to suggest that children’s immune systems are less primed than adults to repair UV damage and immune suppression than healthy adults. This might be why we have seen how sunburns in childhood can greatly increase your chance of skin cancer later on as an adult. I’ve personally seen Facebook comments where parents ask how long they can reasonably keep their young, red headed child outside unprotected. I worry most about already conflicted parents forgoing their child’s sun protection because of fears of Vitamin D absorption.
In the end, articles like this have the potential for great harm because they are so convincing but they are also ill informed and sweeping in their generalizations. The overall take-away from this article is that a certain amount of common sense goes a long way. I do not believe in being puritanical about anything in life. I don’t think people need to live under rocks from fear of exposure to sunlight. I think hats, clothing and shade are still the best forms of protection and I’m the CEO of a company that makes sunscreen. Sunscreens are not perfect but some are definitely infinitely better than others. I truly believe that we have made great steps to making sunscreen the best that they have historically ever been. We as an industry can’t be faulted for making mistakes when we had gaps in knowledge in the past but we can certainly be held accountable if we do not adapt to the evolving science as we continue to learn more. Having said that, let’s not dismiss all scientific progress- that makes for lazy journalism. Some might say the margarine equivalent…