It’s summertime, and by now you’ve no doubt come across reminders and warnings to stay safe in the sun. Excessive sun exposure and sunburns are linked to increased risk of melanoma and skin damage (1), and for decades sunscreen and sunblock have been promoted in protecting the body from excessive solar radiation. That’s great! Nobody wants melanoma and sun-damaged, wrinkly skin, so anything that might help prevent that is awesome, right? Not so fast. While avoiding sunburn is important, sunscreen is not a cure-all, and in some cases, may actually be doing more harm than good. Let’s take a look at some risks and benefits to using sunscreen, and how we can take an informed approach to healthy sun exposure.

What Does Sunscreen Do, and Why Do We Have It?

To put it simply, sunscreen creates a physical or chemical barrier between the skin and the sun’s UV rays. The sunscreen will either absorb or reflect UV rays, protecting the skin from being affected by the UV radiation. Theoretically, this is great. If excessive sun exposure leads to sunburn, and sunburns increase risk of skin cancer or skin damage, sunscreen can be a great way to enjoy the sunshine while reducing the risk. However, this is just theoretical; researchers have not found that sunscreen prevents melanoma or basal cell carcinoma, two types of skin cancer, and, surprisingly, melanomas don’t even usually appear on parts of the body that get regular sun exposure (2). Furthermore, using sunscreen doesn’t guarantee you won’t get burned and it doesn’t protect from all types of sun damage.

One fact that is not debated is that lots of sun exposure can lead to premature aging of the skin. Our own Tawnee Gibson knows about this first-hand, and shares her own story:

“I didn’t consistently use sunscreen in my teens or 20s, and I often left my face and body exposed to the sun day in day out, especially during summer months and my triathlon years (those long brick workouts and swims especially) where even if I did wear sunscreen it’d wear off. To be honest, I loved having really tan skin and face and didn’t care about the ramifications back then; I even went to tanning salons in high school more than I care to admit, sigh. I’m only 32 and my skin isn’t horrible by any means, but you can tell a difference in my signs of sun-related aging and increased freckles/spotting versus my friends of the same age who spent more time inside and who were better with their sunscreen habits. When I was around 30 I felt like sun damage was accelerating faster than ever, so I decided I better do my best to protect my face especially, and hopefully repair some sun damage and slow down signs aging (it worked). My dermatologist said it’s never too late to start and, to some degree, you can repair skin damage related to sun exposure, or at least not let it get worse. That said, nowadays I still don’t always wear sunscreen on my body unless I know I’m going to be outside for a really long time or in a tropical location where the sun is more intense; I’m not fair-skinned and don’t easily burn so I can handle that.”

Sunscreen is not unequivocally necessary in all situations, and it’s not going to outright save you from risks. Like Tawnee, you can pick and choose when you need sunscreen the most and also decide based on your skin tone. Excessive and chronic sun exposure and burning are all bad, but we actually need some unprotected sun exposure for our health—like anything, the dose makes the poison. On top of that, there are ingredients in sunscreens that are potentially bad for us, so we don’t want to keep applying it willy-nilly when we don’t need it, and the bottle of sunscreen that we buy matters. More on this later.

Benefits of Unprotected Sun Exposure

The main (and arguably most talked-about) benefit of direct sun exposure on our skin is the production of Vitamin D. We produce Vitamin D when unfiltered UV rays from the sun interact with our skin, and this process is interrupted when we wear sunscreen. Vitamin D does amazing things for our body, and has been linked to reduced all-cause mortality, reduced risks of many cancers, and lower incidence of metabolic syndrome and type 2 diabetes (1). For athletes we often “use up” our D more than the average population and maintaining adequate D levels may improve performance. Vitamin D can be supplemented if needed, but sun exposure is the ideal way to make it if possible.

The time in the sun needed to make Vitamin D varies due to location, time of year, time of day, and the individual. If you want to get an estimate of when you personally can make Vitamin D based on your location, check out the D Minder app on your smartphone.

Can Sunscreen Be Harmful?

Although sunscreen is great at preventing sunburn, there may be some problematic ingredients that have a possible link to disrupted endocrine function and toxicity (3). Most studies so far don’t prove direct causation, and there is still a lot we don’t know, but chemical ingredients (listed below) may pose threats. Until we learn more it’s probably safe to use sunscreen only when necessary, and don’t go crazy with it if you aren’t going out in the sun for a prolonged period of time. There’s a great Ask the Doctors episode of Endurance Planet where Dr. Minkoff shares his own opinion on sunscreen and the risks associated. The audio starts at 17:30, and the main point of his argument is below (4).

“If you try to deliver a drug, and you compare what dose you need orally, versus what dose you need to deliver it through the skin, the skin absorbs it way better than the GI tract does,” says Minkoff. “The skin is very absorbent, a lot of the toxicities that people get, they get through their skin. So, I think you do have to watch what you do put on your skin. I think that the sunscreen thing is so overdone, because we have an epidemic in this country of Vitamin D deficiency. There has been such a scare from the dermatology community about skin cancer and using sunscreen, that there’s now the epidemic of Vitamin D deficiency. Most of the sunscreens that are sold have a lot of toxic crap in them, and it does get absorbed in the body. So there are more body-friendly sunscreens, and they’re ‘natural  sunscreens’ and they work just as well, but they may not be as pretty or they might not smell as good. If you’re acclimated to the sun and you’re outside, you don’t need sunscreen most of the time, and if you’re out to the point where you’re going to burn, that you wear sunscreen to protect you under those circumstances, but you wear a good one.”

Common chemicals in sunscreen with toxicity risks; best to avoid (5):

  • Oxybenzone – acts like estrogen; may cause hormone disruption in children and adults
  • Octinoxate – hormone-like activity
  • Homosalate – disrupts hormones
  • Octocrylene – higher skin allergy risk
  • Octisalate – mild toxicity concern

Common chemicals with lower toxicity risk; should be ok to use (5):

  • Titanium Dioxide
  • Zinc Oxide
  • Avobenzone
  • Mexoryl SX

Inactive ingredients, i.e. the extra “fillers” that don’t necessarily provide protection are also of concern, one such is methylisothiazolinone (5). Read labels and go for the brands with minimal ingredients and names you can pronounce or recognize

Practical Guide to Sunscreen Use

Now that we’ve covered the risks and benefits to sun exposure and sunscreen, here is what you can do to reap the benefits of both:

  • Choose mineral-based sunscreens over chemical sunscreens when buying and wearing sunscreen.
    • Mineral-based formulas will usually contain zinc and/or titanium dioxide as active ingredients.
  • Buying guide: For the best and safest sunscreen choices, look no further than this fabulous “safe sunscreen” guide put out by the Environmental Working Group (EWG)… Why would we ever try to compete with their brilliant work?! They work tirelessly to investigate ingredients in all common brands, rate sunscreens and provide recommendations for adults and kids. (Beyond sunscreen, they also do great safety ratings for household and personal care products to make your world less toxic and much cleaner.) ON this guide, green boxes with a “1” are your best choices!
  • More SPF is not better! You really only need 30-50 SPF, regardless of how long you plan to be out or how sweaty you’ll get (6).
  • Skip the sunscreen sprays. While they may seem more convenient and offer better coverage, those are myths and often they have more harsh chemicals and inferior protection. (If you ever boat, you will hear that these aren’t allowed because they stain the deck and cause other problems; why would you want this on your body?!)
  • Cover your lips too! Even coconut-oil-based lip balms will provide protection; don’t neglect this part of your body.
  • Get into the sun without sunscreen for about 10-20 minutes around midday for a Vitamin D boost. This is not enough to cause damage!
  • Use clothing as a barrier between you and the sun: If you’re going to be outside long enough to burn, or you’re visiting a location that has stronger sun than where you live, your best bet is to keep your body and face covered with light clothing and hats. From there, use sunscreen on all your exposed skin, especially your face, ears and neck, to help prevent a burn.
  • Use sunscreen prior to long races. If you’re doing a summer marathon or an Ironman, take the time to reapply sunscreen in T1 and/or T2 if you can (despite claims, sunscreens are not waterproof and only water resistant for a short time frame). Race day is for going fast, not working on your tan. Not to mention, it can result in some brutal tan lines if you’re not careful. 😉
  • Know your body—on a day-to-day basis, if you’re going to be outside but know you won’t burn, especially if you tan well, you’re probably ok skipping the sunscreen.
  • Don’t depend on sunscreen to save you. Make smart decisions like avoiding sunburns, which are linked to cancer risks. Sunscreen alone won’t save you from burning.
  • Go see a dermatologist you trust if you notice something out of the ordinary on your skin and are concerned.
    • Tawnee once recorded a podcast with a melanoma expert with tips and advice for those in the sun a lot e.g. athletes, listen here.

—Frank Nordaby