IEver since the turn of the 20th century, when vacations to tropical destinations became more accessible to more people, a deep tan has been a fashionable sign of health and vitality. Unfortunately, decades later it was discovered that the sun exposure needed to create this bronzed glow also generated free radicals that heavily damage dermal structures. We now know that sun exposure is somewhat bittersweet, in that it does stimulate the production of Vitamin D in humans (which is a very good thing from a health point of view), but it also generates free radicals in the skin (which is a very bad thing from an anti-aging point of view). All ultraviolet (UV) light exposure does some amount of damage, which accumulates through years of continual exposure. However, there are ways to utilize sun exposure to maximize the benefits (such as Vitamin D production) while minimizing skin damage (particularly free radicals).
How Photoprotection Works
There are two main types of ultraviolet radiation in direct sunlight that impact the skin. UVB radiation is the one people tend to be most familiar with because it initiates the tanning response and induces sunburn. UVA radiation, on the other hand, damages the skin in a more silent way as it isn’t accompanied by sunburn or other more immediate signs of exposure. So while exposure to UVB can result in more immediately apparent damage, it’s UVA that is most associated with long-term consequences such as skin cancer and wrinkles.
UPF & Broad-Spectrum Photoprotection
People often turn to high-SPF sunscreens to shield themselves from this UV exposure. Unfortunately, what many individuals don’t know is that the SPF rating system used for sunscreens is rather outdated when it comes to protecting the skin from the full UV spectrum. According to the United States FDA, a product's SPF (Sunscreen Protection Factor) numerical value indicates only how long a person can stay in the sun before getting burned, but does not refer to how much the product protects the skin from overall radiation. In other words, it only refers to how long it will take a person to become pink or red (which is variable to the amount of pigment in the skin already). If you can normally stay in the sun 15 minutes before starting to turn pink then a SPF 15 product will let you stay in the sun for approximately 3 hours and 45 minutes before beginning to burn. If you begin turning pink after 10 minutes, an SPF 15 will let you stay in the sun approximately 2 ½ hours before beginning to burn. The formula for determining this is: Minutes x SPF = total exposure time before beginning to burn. For example: 10 (minutes) x 15 (SPF) = 150 (minutes before beginning to burn), or 2 ½ hours. If you're swimming or perspiring this obviously will diminish the protection a topical sunscreen can offer (even if it claims to be waterproof). This is how the SPF rating system works.
This SPF rating system only relates to UVB radiation and the amount of time it takes to begin to sunburn. While protection from UVB and sunburn is important, for anti-aging purposes protection from the UVA light spectrum is also critical (which many sunscreens on the market either do not offer or only partially offer). For more complete coverage the UPF system was created. UPF is a relatively new rating system that is an acronym for Ultraviolet Protection Factor, Ultraviolet Photoprotective Factor, Universal Protection Factor, or Universal Photoprotective Factor (depending on the organization the exact term slightly varies). While the exact name has some fluctuation depending on the institute that is referencing it, the UPF rating system itself is quite standardized and takes a wide spectrum of light into account.
This system works in a very similar manner to the SPF system, but takes into consideration the broader light spectrum when calculating its ratings, instead of just UVB. For instance, a UPF rating of 2 shields the skin from about 50% of the broader UVA/UVB spectrum, a UPF 10 filters out about 85%, a UPF 15 stops about 95%, and an UPF 30 stops about 97%. A UPF that's higher than 30 really doesn’t provide much more shielding. Even using the old SPF rating system a value over 30 doesn’t offer that much more benefit. For example, a regular sunscreen using the SPF rating system that has a SPF 50 still can let approximately 3% of UVB rays through to your skin. The FDA has only recently stated that it plans to limit the SPF rating of a product due to the inability to calculate protection after a certain amount. While that is related to the SPF system, it also has implications for the UPF rating system since the two closely parallel. Given these facts, it seems that the most benefits a topical product can offer will peak in the UPF 15 to 20 range (any higher offers very little benefit versus the amount of the photoprotective ingredients used).
Only a few substances, both natural and synthetic, are available that defend against the broader spectrum of sunlight exposure. The most popular are: Zinc Oxide, Titanium Dioxide, Avobenzone (also called Parsol 1789, but please note it is not the same as Oxybenzone), Mexoryl SX, and Tinosorb. Zinc Oxide and Titanium Dioxide are the only truly natural compounds from that list and these earth minerals are considered classic sunscreen ingredients since they have been used in natural skincare products since before any of the others were created in a lab. The others are artificial, “chemical sunscreens” that either have only limited long-term safety testing behind them or have had safety concerns with long-term use. Mexoryl SX and Tinosorb are legally only available in products sold outside of the US.
According to the Skin Therapy Letter published by the Division of Dermatology at the University of British Columbia (vol. 2, no. 5, 1997), and the US FDA, the light frequency range of UVA is 315-400 nanometers and the UVB range is 280-315 nanometers. These are the frequency parameters by which those two spectrums of light are transmitted. So the full UVA and UVB light frequency range is 280-400 nanometers. The range of protection for the following sunscreen ingredients is listed as: Avobenzone (Parsol 1789) is 320-400 nanometers; Titanium Dioxide is 290-700 nanometers; and Zinc Oxide is 290-700 nanometers. Mexoryl and Tinosorb also have protection in the 290-400 nanometer range, but once again they are not allowed by the FDA in the US and are also patented chemicals. As one can clearly see, the natural minerals Zinc Oxide and Titanium Dioxide are not only superior ingredients for dealing with virtually the entire UVA/UVB range but are also the least potentially irritating, especially on sensitive skin. So why use anything else?
These protective effects of Zinc Oxide and Titanium Dioxide are compounded with the application of topical antioxidants, especially Vitamin C, Vitamin E, and Alpha Lipoic Acid, which work synergistically in the skin to mitigate free radical damage. Carotenoids (photoprotective plant pigments), Seaberry Extract, Red Raspberry Extract, and Rosemary Extract have also been shown to have photoprotective effects on the skin, especially when combined together with mineral sunscreens.
The manner in which a photoprotective product is applied is just as critical to its overall function as its SPF/UPF rating. Probably the most important thing to remember is that this type of product should be applied liberally. Most people only apply about 50% of what is needed to attain the actual SPF/UPF value they think they are getting. If you are applying several skincare products then a general rule is to always apply a photoprotective product last. Another similar rule is to go from “thinnest to thickest.” In other words, a thinner serum that is more aqueous should go on first because it will be best absorbed, while as a thicker lotion or cream will seal in the thinner serum product and also stay on the top of the skin better. Products with a UPF value should come in a thicker consistency since you want the photoprotective compounds to stay on top of the skin or be absorbed only minimally into the epidermis.
It is important to note that if you are using more than one photoprotective product the two do not add up to one UPF number. In other words, applying a product with an UPF 5 and a product with an UPF 10 do not add up to an UPF 15. The same is true when using traditional sunscreens; applying a product with a SPF 5 and a product with a SPF 10 does not add up to a SPF 15. Though using two photoprotective products will increase the overall protection, there is no way of knowing quantitatively by how much. But really you should not be focused on the exact number of an SPF/UPF rating so much as knowing that the product is designed to protect the skin from UV damage based on a natural formulation (since the chemical sunscreens in most mainstream products are far for damaging to the skin than the sun’s UV radiation).
What about applying liquid makeup foundation (one that doesn't contain photoprotective ingredients) over a photoprotective product? If it is a thin, watery type foundation that doesn't have any photoprotective properties then you would in all likelihood be reducing the potency of the photoprotective product underneath. However, if you are applying a standard liquid foundation that is very thick and opaque then there is less risk of affecting the formula underneath. In reality, though, the use of liquid foundations for most individuals is no longer needed with the advent of mineral makeup pressed and loose powders. They go on like any other powder makeup and often offer photoprotective properties of their own. They give even coverage in the same way as a liquid foundation but tend to look more natural and blend in better since they are a powder, and don’t come with the risk of diluting active ingredients from skincare formulas that have already been applied.