Friday, July 24, 2015

Retinyl Palmitate (Just When I Thought.....Part 2)

In this post I wanted to address the claim from the Environmental Working Group's (EWG's) sunscreen guide that retinyl palmitate is a toxic ingredient.

What is retinyl palmitate?
Retinyl palmitate is an ester, consisting of vitamin A and palmitic acid. It is included skin care preparations as an antioxidant and cell regulator. It is also approved by the FDA for use as an additive in food, as well as a supplement. For our purposes we'll be focusing only on its use in sunscreen.

Claim: Vitamin A in sunscreen causes skin damage and is can cause skin cancer.

This is good time to introduce a term called "cherry picking".
From wisegeek.com: 
"Cherry picking has a few different definitions, but it is most often thought of as the process of selecting a small amount of information or data to attempt to prove a point, while ignoring contradicting information. When cherry picking information, a person may end up with a faulty theory or position on a topic because all relevant information was not considered. A person might choose information in this way either on purpose or inadvertently, such as when a person might inadvertently only look at data that is easy to find, presenting a false impression. The term is more commonly used with someone who purposefully ignores contradicting information, however."
The first claim is that retinyl palmitate is carcinogenic. The implication is that the FDA funded National Toxicology Program (NTP) study from 2000 showed this to be true. Here are the problems:
  • study was done on mice, with retinyl palmitate isolated, not in a cosmetic preparation or sunscreen
  • the hairless mice used have a thin epidermis, which allows for more UV penetration, and have a propensity to develop more cancerous tumors
  • the study actually failed to show a link with statistical significance, and even if it had, you then have to assume the findings are 100% comparable to a human reaction

The second claim is that retinyl palmitate causes free radical activity and damage to skin cells. There have been studies linking retinyl palmitate to free radical damage in the skin (1, 2) but it's important to note three points.

  • The studies were again done isolating retinyl palmitate's reaction to UV, not in a skincare or sunscreen formula. 
  • This does not take into account the natural antioxidants in the the skin that counteract free radical activity, not to mention the antioxidants that would be within a well formulated sunscreen
  • Our bodies encounter (and make!) free radicals all the time. It's a complex stew of interactions and vitamin A acts like an antioxidant within this structure. Touting results that were created in a vacuum just doesn't make sense, the skin doesn't work that way.

I believe the concerns about retinyl palmitate are not supported by the science. But, if you only read the cherry-picked elements out of the studies that the EWG presents, I see how it could be alarming at first. Bottom line? Retinyl palmitate was, is and will continue to be a valuable ingredient in our arsenal of chemicals used in skin care formulations. I've linked to all the complete studies above and listed some additional sources below if you want to dig in. Next up is Oxybenzone!

Links to more info/sources:

http://www.paulaschoice.com/cosmetic-ingredient-dictionary/definition/retinyl-palmitate
http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0781.2011.00557.x/full
http://www.personalcarecouncil.org/node/1029


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