Everything you need to know about Sunscreen: A Full Spectrum Guide

Summer is here!

Summer is quickly approaching and so is our exposure to the sun. While sunlight is essential for vitamin D production, it’s also responsible for sunburn, photoaging, and skin cancer. There are two types of ultraviolet (UV) radiation that reach the earth’s surface: UVB and UVA. UVB is responsible for sunburn, freckles, and cancers, while UVA is responsible for photoaging, tanning, and skin cancers as well.  Protecting yourself against UVA and UVB radiation includes: avoiding the sun during peak hours, wearing sun-protective clothing, and sunscreen(1).

When it comes to sun exposure, smart, common sense knowledge can be used here.  To avoid skin damage and sunburn, avoid spending extended time in the sun and seek shade, avoid tanning beds, and tan gradually, without burning.  Wear brimmed hats, protective clothing, and use extra caution near water, snow, and sand. We want to avoid sunburns because history of severe sunburns is associated with an increased risk of melanoma, the most deadly skin cancer(2).  UV exposure may account for up to 80% of visible signs of aging of the skin(3).  

What to Look For in Sunscreen

When extended sun exposure is unavoidable, it is recommended that you protect yourself with sunscreen(4).  There are a few details to look out for when purchasing a sunscreen:

  • Broad-spectrum protection: protects us against both UVA and UVB rays.  

  • Look for a mineral based product with ingredients such as zinc oxide, avobenzone(5), or Mexoryl SX because these are the only ingredients that provide true broad-spectrum protection.  AVOID products containing oxybenzone and retinyl palmitate.

  • SPF (sun protection factor) of 30 or higher.

  • Water-Resistant

  • Sunscreen Cream is superior to spray because they do not pose an inhalation risk and are more likely to provide a thick and even coating on the skin.

How to Appropriately Apply Sunscreen

Studies show that you are likely not applying sunscreen sufficiently7.  According to the American Academy of Dermatology(8):

  • Use enough sunscreen to generously coat exposed skin

  • Mantra “1 ounce, enough to fill a shot glass,” which is considered the amount needed to cover exposed areas of the body.  Adjust according to your size.

  • Apply sunscreen to dry skin 15 minutes BEFORE going outdoors.

  • Skin cancer can also form on the lips to protect your lips with a lip balm of 30 SPF or higher.

  • Reapply every two hours or after swimming or sweating.

Avoiding Oxybenzone and Retinyl Palmitate

According to the Environmental Working Group, 2/3 of sunscreen products contain worrisome ingredients such as oxybenzone, a hormone disruptor, or retinyl palmitate, a form of vitamin A that may harm skin(9).  In fact, government data shows more skin tumor and lesions on animals treated with vitamin A and then exposed to sunlight10.  We want to avoid use of oxybenzone because it has been shown to cause damage and deformation of coral by acting as a hormone disruptor and damaging DNA of coral larvae.  It has also been shown to cause coral bleaching and even coral death. Oxybenzone is widely used in non-mineral sunscreens despite these findings. I do not recommend using any type of hormone disruptor on your skin, and especially not on the skin or your baby.  

A Word on Vitamin D

To ensure that you are getting proper vitamin D levels (because sunscreen blocks vitamin D synthesis), I recommend that you know your levels!  In the meantime, enjoy about 20 minutes of sun exposure without the sunscreen, integrate fish into your diet, and supplement appropriately. Please note that too much vitamin D is just as bad as too little.  

Thank you for reading!


  1. UpToDate: Selection of Sunscreen and sun-protective measures by Elma D Baron MD.  Last updated 4.10.2018

  2. https://www.ncbi.nlm.nih.gov/pubmed/27045074

  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344124/

  4. https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs

  5. https://www.ncbi.nlm.nih.gov/pubmed/20806994

  6. https://www.ncbi.nlm.nih.gov/pubmed/18717957

  7. https://www.ncbi.nlm.nih.gov/pubmed/24313722

  8. https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs

  9. https://www.ewg.org/sunscreen/report/executive-summary/

  10. https://www.huffingtonpost.com/2011/08/18/vitamin-a-for-skin_n_927450.html