Sunscreens – Do They Work to Protect Your Skin?

June 16, 2023

As temperatures are heating up and the first day of summer is upon us, this blog looks into sunscreens and how we can safely get our Vitamin D without burning or damaging our skin!

Natural vitamin D synthesis via the skin is an incredible process we humans possess. We require UVB to synthesize vitamin D. However, sunscreens SPF30 and above absorb 95-98% of UVB leading to lowered Vitamin D levels. This led to researching sunscreen and how it should be best utilized or not!

As a quick reminder, in order to optimize vitamin D production via natural sunlight:

  • Check the UV index is a 3 or higher on a weather app
  • Expose a decent amount of unprotected skin to the sun between 10A-2P until your skin is pink in color or approximately 15-20 minutes a day.

UV Radiation Quick Facts

UV radiation is produced by the sun and is associated with skin cancer. Both UVA and UVB can cause different types of damage to the skin.

UVA rays have wavelengths ranging between 320-400 nm. These rays are present at all daylight hours, penetrate clouds and even windows. UVA rays are very powerful and cause more damage as they penetrate further into the skin. UVA is associated with skin aging and proven to contribute to skin cancer development.

UVB rays have wavelengths ranging between 290-320 nm. These rays gift us the initial step in activating vitamin D synthesis. UVB is mostly responsible for sunburns and does not penetrate further than the epidermis, or outermost layer of the skin. Though UVB rays do not penetrate the skin as deeply as UVA, they can still cause damage.

Depending on the ingredient(s) used, sunscreen products either block, reflect or scatter various wavelengths of light to offer protection.

The Problem with Sun Protection Factor, SPF

Sun protection factor (SPF) products were first invented to simply protect against sunburn. The problem is SPF is only a measurement of UVB, not UVA.  As research continued, it was found UVA is linked to immunosuppression and carcinogenesis. Hence, an SPF value is an unreliable measure of sunscreen’s effectiveness against skin damage as it only reflects protection from UVB.

While there are methods to measure protection from UVA in sunscreen products, currently there is no international standardized method.

Sunscreens on the Market in the US

A 2021 peer-reviewed study of 51 different sunscreens purchased in the US assessed via lab-measured UV absorption found them to exhibit only 59% of the labeled SPF listed on the bottles. The majority also provided only half of the expected UVA protection. Of sunscreens tested, only 34% passed the UVA protection test required of products sold in Europe; whereas our FDA passed  94% of the same products. This is a problem as users have a false sense of protection. The authors conclude, increased market access to UVA protection standards equivalent to SPF protection standards is urgently needed in the US to help consumers reduce harmful UVA and UVB exposure.

People feel more protected with higher SPF values but unfortunately, this provides a false sense of security and does not protect against UVA damage resulting in immunosuppression, formation of free radicals, and possible development of cancer. There is no evidence that an SPF of 50 or higher is more effective than an SPF lower than 50. High SPF products also contain higher concentrations of chemicals than lower SPF products which may pose health risks as many are shown to be endocrine disruptors.

UVA Protection in the US: Broad-Spectrum Sunscreen

The standard label in the US to denote protection from both UVA and UVB is “broad-spectrum.” Broad-spectrum is determined by looking at the critical wavelength (CW), when the sunscreen reaches 90% absorption when exposed to radiation. To be considered broad-spectrum, the CW must be at least 370 nm. Note, having a minimum of 370 nm leaves out 370-400 nm wavelengths of UVA. How much protection do we receive from broad-spectrum products?

The FDA published a study in 2019 assessing 32 broad-spectrum sunscreens of which 40% had suboptimal UVA protection. They conclude sunscreen users in the US may unknowingly receive up to 36% more transmitted UVA when selecting between various broad-spectrum products. This study led to an FDA proposal to bring sunscreen up to date with latest science by identifying maximum SPF, requiring a minimum level of UVA protection, properly labeling, and recognizing sunscreen ingredients as safe. The proposed order has not taken effect and does not require sunscreens to be removed from the market.

UVA Protection in Other Countries

The US is behind the world when it comes to proper UVA protection. In Europe, there is a mandated minimum level of UVA protection in terms of SPF values. Europe’s first UVA measurement system is called the Boots Star System, developed by a UK company called Boots Company in 1992. This system is based on the percentage of UVA absorbed compared to UVB in vitro. The closer the level is to 1, the more UVA protection it exhibits and the more stars it receives: 1 minimum, 2 moderate, 3 good, 4 superior, 5 ultra.

The standard method for UVA protection adopted in Japan is the Persistent Pigment Darkening (PPD) method. PPD is the dose of UV required to produce a slight darkening of the skin with exposure. The PPD value is required to be at least 1/3 that of the SPF value. A PPD of 2-4 offers low UVA protection, 4-8 moderate and 8 or more high. This has been adopted by European nations and is accepted in the US though not commonly used.

Using the PPD method, the UVA protection factor (UVAPF or PA) is used on a graded scale. This coincides with the minimal PPD dose and is graded as follows: PA+ low UVA protection, ++ moderate, +++ high. Korea requires both an SPF (UVB) value and PA (UVA) value on sunscreen products.

The following table summarizes UVA protection systems:

The Problem with Sunscreen Ingredients

Commonly found in many sunscreen products today are the following ingredients: avobenzone, homosalate, oxtinoxate, octisalate, octocrylene, oxybenzone, ensulizole, meradimate, dioxybenzone, sulisobenzone, titanium dioxide and zinc oxide. Sunscreens are approved by the FDA via outdated 2011 safety standards and all ingredients receive a “passing grade.” In the FDA’s 2019 proposal, only two of these ingredients could be classified as safe and effective: titanium dioxide and zinc oxide.

The following table summarizes these chemicals:

According to studies published by the FDA, octinoxate, octisalate, octocrylene, oxybenzone, homosalate and avobenzone are systemically absorbed in the body after just one use and could be detected in the blood and skin weeks after use has ceased. Various studies show these chemicals demonstrate the potential to disrupt hormones, are measurable in the blood, urine and breast milk.

July 7, 2022 the European Commission published updated regulation on the safety of oxybenzone, octocrylene and homosalate due to endocrine disruption and health concerns. They found the current levels of oxybenzone and homosalate were not safe and proposed a limit of 2.2% and 1.4% respectively. In the US, sunscreen products can contain both of these chemicals at concentrations up to 6-15%. Why?

How to Choose a Safe and Effective Sunscreen Product

Look for mineral based products such as titanium dioxide and zinc oxide. These are the only two ingredients recognized as safe as per the FDA. You also want to be sure to read the inactive ingredients as these are typically loaded with various chemicals.

For best UVA protection, you want the following: PA+++, PPD 8-16, a minimum CW of 370 nm, star rating of at least 4.

An excellent resource to use when determining what sunscreen to use or any skin product, search all products in the EWG’s Skin Deep Database. This is backed by scientific research and gives you a hazard score of the product. If you google “top sunscreens” and search them on EWG’s system, they are all hazardous! Beauty counter’s sunscreen cream without minerals or tinting were not hazardous and are effective. Note Beauty Counter’s sunscreen with minerals, tint, or spray delivery system were hazardous as per EWG’s evaluation.

Other Potential Sun Protection   

Carotenoids are pigments in algae, plants and bacteria producing yellow, orange and red colors. A variety of foods from carrots to tomatoes to salmon achieve their color from carotenoid content. Carotenoids boost the immune system, are potent antioxidants and provide a host of health benefits. In vitro and in vivo studies show carotenoids have the ability to suppress UVA and UVB induced damage. While no oral agents will prevent you from getting a sunburn, daily supplementation with carotenoids in addition to sunscreen has been clinically shown to be protective against UV radiation.

Astaxanthin is an antioxidant protective for you from the inside out. Its antioxidant effects are more potent than other carotenoids. It is what gives flamingos and salmon their nice pink color! It is a natural sunscreen for marine plants! It can make you more resistant to skin damage and skin aging from the sun. When applied to skin cells in culture, astaxanthin prevented UV-induced damage. An added bonus is eye protection, anti-inflammation, mitochondrial protection, immune modulation, improved skin elasticity and wrinkle reduction. Dosages range between 4-12 mg/day.

Lycopene is a powerful antioxidant and is found in high amounts in tomatoes and many red or pink colored fruits. In vitro studies show lycopene reduced UVB induced lipid peroxidation or damage to lipids caused by radiation. Studies demonstrated the following using dosages ranging between 10-16 mg/day:

Beta-carotene has also shown evidence of photoprotection:

  • Pre-treatment with 24-30 mg/day of beta-carotene before sun exposure reduced the intensity of redness
  • Subjects with Fitzpatrick skin type II given 24 mg oral beta-carotene daily had reduced severity of UV induced redness

Lutein and zeaxanthin have also demonstrated anti-carcinogenic and anti-aging properties against UV damage. Oral supplementation with lutein has shown a reduction in damage caused by UVA radiation and photocarcinogenesis.  Dosages include: Lutein 10mg, zeaxanthin 2mg.

Topical melatonin has been shown to protect against UV-induced skin damage and sunscreen products can be enhanced with melatonin. Other potential photoprotective agents include nicotinamide (vitamin B3) and green tea polyphenols (EGCG).

While optimizing your vitamin D levels via natural sunlight, always remember to protect yourself from burns.  Enjoy the warmth and benefits of the sun. Happy Summer!

Have an awesome day!  Dr D

Posted in Sunscreen