A recent post by Sarita Coren called for an open discussion about sun protection. Concerns were voiced and questions were raised; vital because our relationship to the sun is still an open book despite seemingly conclusive evidence supporting widespread sunscreen use. Questions persist that may reveal research gaps that could bring us closer to an understanding of how we can benefit from the sun without compromising our health.
The principle behind sunscreen is simple: cover the surface of the skin with a substance that prevents UVA/UVB radiation from damaging the skin. Analogous to clothing, sunscreen functions like a second skin shielding it from the sun while allowing it to breath. However, unlike clothing, this type of dermal covering has problemmatic issues that are still unresolved. The benefit of clothing, especially loose fitting cotton is that it does not disrupt the micro environment of the skin, allowing the body to function normally. It is a mechanical approach to suncare that does not impact the body as a system.
Chemical sunscreens, however, work through the use of carbon based compounds, such as oxybenzone, octinoxate, octisalate and avobenzone that create a chemical reaction changing UV rays into heat and then releasing that heat from the skin. These compounds may not be altogether stable and can degrade when exposed to UV radiation, causing them to oxidize and fall apart, release free radicals which, in turn, attack healthy skin cells. A double whammy. Avobenzone is one such compound that has to be photo-stabilized through the addition of Oxybenzone or delivered through liposomal encapsulation (a bubble that delivers an ingredient to a specific surface area of the skin or subcutaneous level). This process is so problemmatic that I won’t even delve into the myriad questions I have about how the body is affected. Instead, I will focus on mineral sunscreens.
Mineral sunscreens such as Zinc oxide and Titanium dioxide work by physically deflecting, scattering or even absorbing (in the case of nano particles) the sun’s rays. Due to their flat molecular structure, these minerals can be spread thin enough to cover large areas of the skin at concentrations between 15-25% for Zinc oxide and 5-15% for Titanium dioxide. However, the physical characteristics of these molecules, particularly Zinc oxide, causes them to clump together resulting in holes and/or uneven coverage. The medium used to suspend these minerals must allow for minimal clumping (viscosity, polarity, surface tension are all factors) which makes homemade sunscreens a poor DIY option. Sunscreens really need to be manufactured in a controlled environment and tested for efficacy which is why they are considered an over-the-counter drug. Even then, one cannot rely on the stated SPF for a variety of reasons: not applying enough product (to avoid the white skin effect), failing to reapply, perspiration causing product to run, product being rubbed off, etc.
The use of nano particles reduces the white tone imparted to the skin but is less protective since the particles are so small. The smaller diameter, the thinner the shield. They are also occlusive (blocking pore openings). This can prevent perspiration and the release of toxins, a function of the skin as an excreting organ. Research is still inconclusive about nano particles that are absorbed transdermally. Once these particles enter the bloodstream, they obviously have to be metabolized. Zinc oxide is a mineral that can help boost the immune system, but not Titanium Dioxide. How would it be metabolized? Would it be excreted? What would be the rate of excretion? Would it bio-accumulate? If so, where would it be stored; in major organs, bones or fatty tissue? Would it be reactive to other elements in the body? Would it bind with other elements? Could it be chelated?
Our bodies have evolved over millions of years to be hairless and exposed to the sun. This allows for efficient perspiration, cooler basal temperatures and better use of calories with greater physical output. Our bodies are designed to function consistently throughout the day, which means we are meant to be exposed to sunlight, especially at midday. In addition, Homo Sapiens, regardless of geographic location or climate conditions have the same hairless bodies. This might be a clue that sunlight is desirable for our well-being. The difference in skin tone is due to melanin production, a reaction that evolved into a genetic trait. Melanin production is the way our skin prevents UV damage. Conversely, burning is our bodies way of telling us it is being damaged by the sun. UVB rays are the ones that burn, but UVA rays are the ones that damage.
The main benefit from exposure to sunlight is the production of vitamin D which promotes healthy immune function and protects the body from osteoporosis, heart disease, cancers of the breast, prostate, and colon. Sunlight has other benefits; protecting against depression and insomnia by promoting melatonin production which regulates our sleep/wake cycles. Sleep is key to remaining healthy as it allows resting metabolic states and elimination (mostly through the skin) to take place. If we do not get quality sleep each night our bodies experience systemic stress through unbalanced hormones which can lead to chronic illness.
Light skinned people are most receptive to sunlight, their skin thirsty for every last ray in a sun starved climate. They can get their daily Vitamin D dose through 15 minutes of total body exposure at midday when the sun is high in the sky (that’s when UVB rays penetrate the atmosphere). Conversely, darker skin needs longer exposure in order to receive the same benefits. As the skin tans it needs longer exposure to generate enough vitamin D3 for the body, so tanning is not necessarily beneficial.
Supplementation is the only other alternative to getting enough of this vital hormone (yes, Vitamin D is a hormone). However, most commercial supplements are synthetically derived, which could be a factor to consider. In addition, supplements can also tax the body’s metabolism. Knowing that every body is different (age, size, sex) it’s hard to gauge exactly what the body needs at any given time. A one size fits all approach may not be the best approach.
It turns out we know very little about the skin’s surface and the microbiome that covers approximately 2 square meters of our body. While our skin acts as a shell to simultaneously contain and protect the body, it’s also a membrane that allows the release of toxins and vapor (perspiration). It also produces sebum which protects the skin.
Our skin is home to trillions of bacterial (probiotic) colonies like Staphylococcus epidermidis and fungi that vary from region to region, from moist armpit to larges surfaces like the back. These bacterial strains offer protection by secreting antimicrobial peptides (small proteins that kill harmful invaders) to protect themselves. In protecting themselves, they also protect us. The bacterial strains residing on the skin are unique to EACH individual and are acquired at birth (1/10 of the cells in our body are human, 9/10 are bacterial). The only sterile environment is the womb but once a baby passes through the birth canal, it acquires its first bacterial strains. That is why it’s important to not wash the vernix off a baby, especially since washing not only removes bacteria, it changes the pH of the skin which can allow hostile bacteria (like Staphylococcus aureus) to flourish. The total number of bacteria is constantly in flux depending on age, immune function, sex, sun exposure, diet, hygiene and environment. In general, the more diverse these bacterial colonies are, the more protection they offer. Over zealous hygiene and antibacterial products wreak havoc and can lead to potentially dangerous situations (resistant, hostile strains, etc.).
With this in mind, the basic problem with sunscreen as a second skin is that it does not recognize the epidermis as a protective/excreting organ. Some further questions come to mind.
Zinc oxide is a potent antimicrobial that can be used as a stand alone preservative in emulsions. In fact, sunscreen products containing zinc oxide are often self preserving. How does the use of Zinc oxide affect healthy skin flora, especially when it is formulated in a waterproof base? Do probiotic bacteria need sunlight in order to function properly? My guess is “yes”. In which case, covering large expanses of the body with a mineral that impacts friendly bacteria and prevents sunlight from reaching them, potentially changing the skin’s pH could have an adverse effect (the way antibiotics wipe out intestinal bacteria).
When sunlight hits the skin a chemical reaction takes place. Could friendly bacteria help our body protect itself from the deleterious effects of UV radiation? Sebum lubricates and waterproofs the skin, maintaining its acid mantle. More importantly, it has anti-oxidative properties that play an integral role in photoprotection by preventing UV-induced free radical damage to skin and offering anti-inflammatory attributes. This is probably one of the most exciting aspects that could point to a useful area of research. There are several potent anti-inflammatories like raspberry seed oil, carrot seed oil, avocado oil that could offer a simple solution to a complex problem of how to help our skin benefit from the sun with minimal damage.
The other proactive option is to cleanse with oils and bathe less frequently or wash “petty” parts between weekly hammam style baths (deep cleansing, full body exfoliating, relaxing, nourishing). With all of the healthy attributes provided by sebum and our own probiotic colonies, why would we want to wash them away? Sunburns are more accute after swimming or bathing due to Sapienic acids (naturally occurring in sebum) being removed when sebum is washed away. More proof to preserve what the body works so hard to produce.
There is still much we need to learn about the skin’s micro environment and how the body has evolved to exist in a complex world. A major part of this equation has always been the sun. After millions of years of evolution we owe it to our bodies to understand how it works before prescribing solutions that can compound the problem.
Take a fantastic voyage across the surface of your body and don’t forget to ask questions. Lots of them.