Sunscreen Myths Debunked
Intro
I’ve been seeing a lot of skincare posts on social media (probably because of the algorithm), and I’ve been seeing some interesting claims from various health and wellness influencers on the internet. And since I usually take most things on social media with a grain of salt, I like to do deep dives on the many skincare myths that I’ve seen circulate social media and beyond in the internet. Most recently, I’ve been seeing a lot of myths about sunscreen, and I want to address them today and share what science has indicated.
In this blog post, I am addressing 4 sunscreen myths that I’ve seen circulate social media:
Myth 1: Sunscreen causes vitamin D deficiency
Myth 2: Dietary antioxidants can replace sunscreen
Myth 3: Oxybenzone & avobenzone UV filters are the same as benzenes
Myth 4: Sunscreen is toxic since it can be absorbed
NOTE: THIS BLOG POST IS MEANT TO BE EDUCATIONAL ONLY, AND IS NOT MEANT TO DIAGNOSE, PREVENT, TREAT, OR CURE. PEOPLE SHOULD ALWAYS CONSULT THEIR TRUSTED LICENSED PROVIDER BEFORE TRYING ANY NEW TREATMENTS
Myth 1: Sunscreen causes vitamin D deficiency
This myth makes me ask the question: Does sunscreen really cause vitamin D deficiency?
Well, in order to answer this, we first need understand how sun exposure and vitamin D are connected, and how sunscreen could inhibit that connection.
How vitamin D is made from sun exposure:
According to literature, vitamin D production needs sun exposure. Cholesterol is first undergoes transformation to a vitamin D precursor called 7-dehydrocholesterol in the skin. After the skin is exposed to UV-B rays from sunlight, the vitamin D precursor is transformed into previtamin D3, then into Vitamin D3 (but this form of Vitamin D3 is not active). Once Vitamin D3 ends up in the liver, it turns into 25-hydroxyvitamin D3, aka 25(OH)D, (still not an active form of Vitamin D3). And finally, 25-hydroxyvitamin D3 ends up in the kidneys to turn into the active form of vitamin D called 1, 25-dihydroxyvitamin D3.
In short: Sunlight helps make inactive Vitamin D3, which then needs to go through the liver and the kidneys to turn into active Vitamin D3.
So, it could be theorized that blocking sunlight exposure may lead to vitamin D deficiency… But, what does science say?
Does sunscreen cause vitamin D deficiency?
Scientific evidence indicates that normal usage of sunscreen “does not generally result in vitamin D insufficiency.” Additionally, a scientific review published in 2019 indicated that there is “little evidence that sunscreen decreases 25(OH)D concentration when used in real-life settings.” And authors of this 2019 review continue to write, “while the experimental studies support the theoretical risk that sunscreen use may affect vitamin D, the weight of evidence from field trials and observational studies suggests that the risk is low.”
Takeaway:
Scientific literature suggests that normal use of Sunscreen does not generally lead to reduced vitamin D
Myth 2: Dietary antioxidants can replace sunscreen
This myth makes me ask the following: What do antioxidants do, and why are they important for skin health? How could dietary antioxidants replace or mimic the effect of sunscreen?
What are antioxidants & what do they do?
Antioxidants are compounds that neutralize reactive oxygen species (ROS), also known as “free radicals”. Free radicals are compounds that are naturally made intrinsically by cells when doing normal biochemical processes, such as making cellular energy, but can also be formed when the cells and tissues are exposed to external factors, like sunlight.
When looking at free radicals in the skin, research indicates that signs of photo-damage and photo-aging can take place, such as wrinkles, melasma, hyperpigmentation, non-melanoma skin cancer, and more. And when looking at free radicals at a more-global perspective, free radicals have been implicated in heart health, neurodegenerative issues, and more.
Now, how could antioxidants support skin health?
How do dietary antioxidants affect skin health?
A 2012 review suggests that there is a link between nutrition and skin aging, indicating that “fruit and vegetables consumption may represent the most healthy and safe method in order to maintain a balanced diet and youthful appearing skin.” Another study completed 2017 on animal models investigating the effect of astaxanthin, a type of antioxidant, and UV-induced skin damage saw that “dietary astaxanthin accumulates in the skin and appears to prevent the effects of UVA irradiation.”
And more recently, a 2021 longitudinal study looking at the long-term effects of oral consumption of foods with high antioxidant capacity on skin health showed that adults 45 years and older who ate foods with high antioxidant capacity “experienced approximately 10% less photoaging over 15 years than those who ate foods with low antioxidant capacity.”
So, literature seems to suggest that dietary antioxidants have a positive effect on skin health… But, how do dietary antioxidants compare to sunscreen products for photo-protection and preventing photo-damage and photo-aging?
How do dietary antioxidants compare to sunscreen?
After going through the literature, I was not able to find many studies that have compared dietary antioxidant intake to sunscreen use. I did find one article that looked at sunscreen use and oral supplementation of 30 mg of beta-carotene, a type of antioxidant
In this 2013 study, they divided the 903 subjects into 4 groups: 1) daily use of broad-spectrum sunscreen + 30 mg of beta-carotene supplementation; 2) daily use of broad-spectrum sunscreen + placebo supplementation; 3) “discretional use” of sunscreen + 30 mg of beta-carotene; and 4) “discretionary use” of sunscreen + placebo. Researchers found that daily use of sunscreen led to “no detectable increase in skin aging after 4.5 years”, and that beta-carotene supplementation had “no overall effect on skin aging.” And from this, researchers concluded that regular sunscreen use slows down skin aging and that beta-carotene supplementation had no effect on skin aging. It should be noted that the researchers acknowledge that some outcome data was missing. Given that this was the only study I could find, and given that there were some flaws in this 2013 study, more studies are needed to better understand how dietary antioxidants compare to sunscreen use.
There are many studies that look at topical antioxidants and sunscreen though!
In regards to topical antioxidants, a 2017 review indicated that topical antioxidants may be helpful for reducing the effects of free radical damage in the skin. And, studies completed in 2011, 2017, and 2019 concluded that antioxidants add protection to sunscreen through a synergistic mechanism for improved photo-protection.
Takeaway:
There are limited-to-no studies to conclude that dietary antioxidants can replace sunscreen. Current evidence indicates that topical antioxidants improves the protective effect of sunscreen.
Myth 3: oxyBenzone & Avobenzone UV filters are the same as benzene
This myth makes me ask: How did this myth even start, what is oxybenzone, & what are benzEnes?
How the myth started
This myth that oxybenzone and avobenzone are the same as benzene started when the Valisure study came out in May 2021 that showed that some popular sunscreens contained benzene in them. With the sensational hype of the Valisure study, many people were confusing the chemical UV filters oxybenzone and avobenzone with benzene, and started to have concerns (and come to believe) that oxybenzone and avobenzone are the same as benzene.
So, what are these benzone UV filters and what is benzene?
What is oxybenzone & Avobenzone?
Oxybenzone and avobenzone are common chemical UV filters used in sunscreens, and I have found no reports that say that oxybenzone and avobenzone turn into benzene.
Oxybenzone and avobenzone are also chemically different from benzene, with benzone UV filters having multiple aromatic rings in their chemical structure them while benzene has only 1 aromatic ring in its chemical structure.
Click here to see the oxybenzone structure
Click here to see the avobenzone structure
Click here to see the benzene structure
What are benzenes & why are they important to know?
According to the National Library of Medicine, benzene is “used as a solvent, as a chemical intermediate, and is used in the synthesis of numerous chemicals,” and it’s important to know about benzene since it is a “known human carcinogen and is linked to an increased risk of developing lymphatic and hematopoietic cancers, acute myelogenous leukemia, as well as chronic lymphocytic leukemia.”
With that, sunscreens that contained benzenes were contaminated with benzene, and contamination could have taken place during any step of the manufacturing process of those sunscreen products. Click here to see all of the sunscreens that Valisure found to have benzene.
Takeaway:
Oxybenzone & avobenzone are not the same as benzenes, and benzene contamination in some sunscreens is due to an issue in the manufacturing process.
Myth 4: Sunscreen is toxic since it can be absorbed
This myth makes me ask the following: What does the term “toxic” mean in the medical realm? What are the different UV filters commonly used in sunscreen, and are they all absorbed?
Definition of toxicity
According to MedicineNet, the medical definition of “toxicity” is: “The degree to which a substance (a toxin or poison) can harm humans or animals.” And according to MedicineNet, toxicity can be classified into 3 different types of toxicity, such as: Acute toxicity, subchronic toxicity, and chronic toxicity. Additionally, environmental medicine is a field of medicine that looks at the effects of environmental substances & exposures and their toxicity on health. According to the American Academy of Environmental Medicine (AAEM), environmental medicine considers the “total load” of toxicants in addition to various internal factors when looking at how substances could lead to changes in health.
Types of UV filters commonly used in sunscreen products
Ultraviolet (UV) filters are necessary in sunscreen products to protect the skin from UV radiation from the sun. There are different types of UV rays, and the ones important to look at are UV-A and UV-B rays. According to research, UV-A rays can go into the deeper layers of the skin (the dermis) to cause symptoms of photoaging and UV-B rays are mainly absorbed by the upper layer of the skin (the epidermis) to cause sunburn. With this, it is important to have a sunscreen product that is broad-spectrum and provides protection against both UV-A and UV-B rays.
There are 2 classes of UV filters that can be found in sunscreen products: Inorganic filters and Organic filters.
Inorganic filters (also called physical filters) are mineral-based, such as zinc oxide and titanium dioxide. Organic filters (also called chemical filters) are synthesized chemicals, and some common ones that can be found are: Oxybenzone, Avobenzone, Octinoxate, Octisalate, and Trolamine salicylate. However, there are many more types of organic filters that can be found in various sunscreen products.
The two different types of filters also work differently to protect skin from UV rays. Inorganic filters work by reflecting and scattering light to protect the skin and organic filters absorb energy from UV rays to protect the skin.
So, now we know the different types of UV filters found in sunscreen. Now, how well are these UV filters absorbed and what conditions have these filters been linked with?
Absorption of physical UV filters
When looking at zinc oxide absorption, a small study completed in 2010 on human subjects showed that an overwhelming amount of zinc from “nano sunscreen” and “bulk sunscreen” was not absorbed and that only a small amount was absorbed, with female subjects using “nano sunscreen” showing more zinc in urine. A small 2019 study further investigated zinc oxide nanoparticles and its safety in humans, and researchers found that repeated application of zinc oxide nanoparticles “appears to be safe, with no evidence of [zinc oxide nanoparticles] penetration into the viable epidermis nor toxicity in the underlying viable epidermis.” When looking at the absorption of titanium dioxide, a 2020 scientific review concluded that “limited quantities of [titanium dioxide nanoparticles] may be absorbed systemically.” And, a 2018 study reviewing both zinc oxide and titanium dioxide concluded that “studies both in vivo and in vitro have found that these minerals do not permeate the skin to any significant degree.”
Absorption of Chemical UV filters
A 2007 in vitro study completed on animal skin and human epidermis looking at the absorption of 5 chemical UV filters (2-ethylhexyl-4-methoxycinnamate/octinoxate, 4-methyl benzylidenecamphor/enzacamene, butyl methoxydibenzoylmethane/avobenzone, 2-ethylhexyl-2,4,5-trimethoxycinnamate, and di(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate) showed that octinoxate, enzacamene, and avobenzone were absorbed through animal skin, and octinoxate and avobenzone were absorbed through human epidermis.
And, a 2019 study completed on human subjects investigating the effects of real-life use of chemical UV filters (octocrylene and avobenzone) for 1 day found that” urine detection rates of avobenzone and octocrylene were low.” This study also looked at urinary markers for a metabolite of octocrylene, called 2-cyano-3,3-diphenylacrylic acid (CDAA), and they found that “CDAA showed a high detection rate” in urine. And, authors of this study concluded that “metabolite CDAA in particular showed a markedly increased renal excretion over the whole sampling period and indicated high internal exposure to [octocrylene].”
Conditions associated with UV filters
A 2012 review looking at the toxicity of UV filters indicated that chemical UV filters are “known to be allergenic triggering photoallergic contact dermatitis,” and explain that photo allergic contact dermatitis is a “skin allergy reaction to light mediated by contact with some chemical compounds.” And, authors of this 2012 review explain that this skin allergy reaction may occur because of the unstable degradation of chemical UV filters when these chemical UV filters absorb UV radiation.
Beyond skin reactions, UV filters have been linked to hormone disruption. A 2016 review reported that benzophenone-type UV filters have hormone-disrupting effects, acting on estrogen receptors, androgen receptors, and progesterone receptors in vivo and in vitro. The authors of this 2016 review also note that certain chemical UV filters can also affect thyroid function in animal models. A 2018 review looking at the endocrine-disrupting properties of UV filters indicated that octylmethoxycinnamate/octinoxate exert “estrogenic, anti-androgenic, anti-progestenic and anti-thyroid activity.”
Researchers have also investigated maternal exposure to UV filters in a 2018 study. Using urine samples from pregnant females in their second trimester, researchers looked for 2 chemical UV filters: benzophenone-1 (BP-1) and benzophenone-3/oxybenzone (BP-3). Researchers also looked at blood levels of 4-hydroxy-benzophenone (4-HBP), a type of chemical UV filter. Beyond looking for these UV filters, researchers also checked maternal blood levels of thyroid hormones (T3 and T4) and growth factors in addition to checking birth outcomes. What researchers found were that:
There were no significant association between BP-1 and BP-3 with maternal thyroid hormones or growth factors
There was a significant link between higher 4-HBP and higher thyroid hormone and higher growth factors in mothers with male fetuses
There was a significant correlation between higher 4-HBP and lower free T4 levels in mothers with female fetuses
Mothers with medium 4-HBP exposure had male infants with “significantly lower birth weight and smaller head and abdominal circumferences.” And for female infants, “there was no significant association between maternal serum 4-HBP concentrations in the second trimester and any of the recorded birth outcomes”
With these findings from the 2018 study, it could be concluded that 4-HBP is linked to changes in maternal thyroid hormone and growth factors and that dose-dependent exposure of 4-HBP is linked to changes in fetal growth. Although, it should be noted that correlation does not mean causation, and that these observations were just links and associations. More studies need to be completed to understand how these chemical UV filters play a role in fetal and human health.
In 2019, the FDA proposed new rules on sunscreen and categorizing them in new categories: Category I - GRASE (Generally Recognized as Safe and Effective); Category II - non GRASE; and Category III—insufficient safety data to make a positive GRASE determination. From this proposed new category system, only zinc oxide and titanium dioxide are categorized as Category I - Generally Recognized as Safe and Effective, while all other UV filters are either Category II, Category III, or have not been given a GRASE rating.
Takeaway:
inorganic filters (zinc oxide & titanium dioxide) have been the only UV filters designated as “Generally Recognized as Safe and Effective.” And, LITERATURE indicates that Zinc oxide & TITANIUM dioxide do not permeate the skin to any significant degree. In regards to organic filters, more studies need to be completed as these chemical UV filters have been linked to skin allergy, hormone disruption, and more.
Shopping for sunscreen
I have been fortunate to try many sunscreens, and have learned what I personally like and don’t like in a sunscreen when shopping for a new sunscreen. This section is just my opinion and I explain what I look for when shopping for a sunscreen and I list my top 4 sunscreens that I have tried and liked. By no means is this meant to be taken as medical advice, and is not meant to treat, prevent, or cure. And, always speak to your doctor before buying or trying any new skincare products or treatments.
When shopping for sunscreen, I consider 3 things:
Type of UV filter: I tend to only shop for physical UV filters, which are mineral-based sunscreens (such as zinc oxide and titanium dioxide).
Feel of the product: I don’t like products that feel too heavy on the skin and won’t blend in well with my skin tone. The issue with mineral sunscreens is that they tend to be thick and tend to leave a white cast. Because of this, I sometimes choose mineral SPF tinted with iron oxide.
Antioxidants: If there are antioxidants in the product, that’s a plus to me! (Since we spoke about how science shows that antioxidants add protection to sunscreen)
My top 4 sunscreens
Here are my top 4 sunscreens that I have tried from brands that I have no financial ties to, and always remember to speak to your trusted doctor before starting any new products or treatments.
1) Farmacy Green Defense Mineral Sunscreen SPF 30
Pros: This mineral sunscreen does not leave a white cast on my skin with my skin tone (Fitzpatrick Type V). I also appreciate that it has it has moringa-based antioxidants in it, and I like how light it feels on the skin compared to other mineral sunscreens I have tried in the past.
Cons: There are a lot of excipients in the product.
2) Naturopathica Calendula Essential Hydrating Lotion Broad Spectrum SPF 30 Sunscreen
Pros: Much like the Farmacy sunscreen above, this product didn’t leave a white cast on my skin with my skin tone. I also liked that it felt light on my skin (lighter than the Farmacy sunscreen) and that its ingredient list had antioxidants and less chemicals compared to Farmacy.
Cons: Price point - this product is an investment at $68 for 1.7 ounces (as of October 2021), while the Farmacy sunscreen is $36 for 1.7 ounces (as of October 2021). This price point is the main reason why Naturopathica is number 2 for me on my list. Beyond that, this product is absolutely amazing, and if it was closer in price to the Farmacy sunscreen, I would choose this one from Naturopathica.
3) Josh Rosebrook Nutrient Day Cream SPF 30 (click here for the tinted version)
Pros: This is one of the cleanest sunscreens I have put on to date, and has the least amount of chemicals in it compared to Farmacy’s and Naturopathica’s sunscreens. I have had the opportunity to try both the regular and the tinted versions of this product, and with my skin tone, I preferred the tinted version since the regular version did leave a white cast on my skin.
Cons: This product did feel heavier compared to Farmacy and Naturopathica. Additionally, the price point of the product is $80 for 1.7 ounces (as of October 2021) for the regular version and $90 for 1.7 ounces (as of October 2021) for the tinted version. So, this product is definitely an investment, but you can’t really beat how clean the ingredient list is!
4) SurfDurt “The OG” SurfDurt Sunscreen in Neutral Tan SPF 30
Pros: Out of the 3 sunscreens above, this sunscreen from SurfDurt is the cleanest with just 8 ingredients in its ingredient list. EIGHT! This product does have a tint from the iron oxide, and from my experience, if you put too much on, it leaves some sort of cast on the skin (not a white cast though) that doesn’t blend in too well with my skin tone. It’s also great that this product is a solid sunscreen, which makes it really great to travel with due to carry-on liquid restrictions. Lastly, this product is the cheapest out of all of the sunscreens listed here at $24.99 for 2 ounces (as of October 2021).
Cons: This product is thick and doesn’t blend in well with my skin tone despite it being tinted with iron oxide. Other than that, it’s a great product and a great option for those traveling!
The Skin Cancer Foundation recommends using broad spectrum sunscreen that protects against both UV-A and UV-B radiation that is SPF 15 or higher for everyday occasional sun exposure and SPF 30 or higher for extended outdoor activities. They also recommend using 2 tablespoons (or 1 shot glass’ worth) to the exposed areas of the face and both, and that a nickel-sized amount is necessary for the face alone. In regards to application and going out, the Skin Cancer Foundation recommends applying sunscreen 30 minutes before sun exposure and to reapply every 2 hours.
Summary & Takeaways
The main takeaway from this post is that you shouldn’t always believe what your favorite wellness influencer on social media says. And, I feel that it’s important to keep wellness influencers accountable and ask them for the research behind the claims they are preaching.
So, here’s a run down of the sunscreen myths I’ve seen on social media and what science says:
Myth 1: Sunscreen causes vitamin D deficiency
What science says: Normal use of sunscreen does not generally lead to reduced vitamin D.
Myth 2: Dietary antioxidants can replace sunscreen
What science says: There are limited-to-no studies to conclude that dietary antioxidants can replace sunscreen.
Myth 3: Oxybenzone & avobenzone UV filters are the same as benzenes
What science says: Oxybenzone & avobenzone are not the same as benzene, and benzenes are a contaminant found in some sunscreens due to an issue in the manufacturing process.
Myth 4: Sunscreen is toxic since it can be absorbed
What science says: Inorganic filters (zinc oxide & titanium dioxide) have been the only UV filters designated as “Generally Recognized as Safe and Effective.” And, literature indicates that zinc oxide & titanium dioxide do not permeate the skin to any significant degree. In regards to organic filters, more studies need to be completed as these chemical UV filters have been linked to skin allergy, hormone disruption, and more.
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