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Do you need to reapply sunscreen indoors? episode 205


It’s a special episode with Perry and Sarah Bellum. On today’s episode we’re going to be answering your beauty questions about 

  1. Do you need to reapply sunscreen if I’m indoor all day?
  2. Why is ferulic acid used with vitamin C?
  3. Are vampire facial good for your skin?
  4. Why isn’t there more recycling?
  5. Does Revitalash really work?
  6. Are cosmetician brands really better?
  7. What other podcasts do you listen to?
  8. What are some trends you see in new technology for beauty products?

Beauty News

How accurate are those beauty product DNA tests

This article was title How accurate are those beauty product DNA tests and it was posted on the Huffpost. They were pondering whether beauty products formulated with your DNA profile in mind were effective. They gave examples of the company Strands Hair Care which gets your DNA profile from a sample of your hair to formulate hair products for you and ORIG3N which offers beauty product advice based on beauty DNA tests.

They did the standard two sides thing where the expert in favor of the technique was, of course, selling products and DNA consultations. She used a lot of “sciencesplaining” and concluded that it definitely worked. The article also offered a reference to a 2018 paper published in the Journal  Clinical, Cosmetic and Investigational Dermatology and suggested that research supported the use of individual DNA testing for cosmetic application. I read the article and that was not the conclusion. The authors merely said it might be possible.

At present, I don’t think it is possible. There are a lot of things going against DNA testing for your skin or hair but the main one is that we formulators have no idea what to do with the information. Formulating is not a high-precision activity. We find ingredients that generally work and make educated guesses to how much should be included in a formula. Even if a formulator knew everything about your DNA sequence we don’t know what specific genes matter for your skin or hair, how they interact to produce collagen, elastin, or to grow hair. And it says nothing about the external environmental effects on your skin and hair. Identical twins might not respond the same to identical treatments. For example, if one twin got their hair bleached and the other didn’t, their genetics would not tell you what type of hair products were best for them.

No doubt these types of products will continue to gain in popularity. Or at least more companies are going to be launching them.  But it’s still just a marketing gimmick and you aren’t going to get any significant benefit by having a product designed specifically for your skin or hair DNA.

Question 1 (Audio question)

If sunscreen isn’t exposed to the sun can it last all day? Do I need a product to reapply sunscreen if I’m inside all day?
The idea of reapplying sunscreen is not primarily because the sunscreen breaks down. In fact, sunscreens mostly do not break down upon exposure to sunlight. According to Dr. Steven Q. Wang, the director of dermatology at Memorial Sloan-Kettering Cancer Center the advice to reapply sunscreens every two hours was mostly because people don’t put enough on initially. This was a way to get people to apply closer to the right amount. I also think that when you’re at the beach and you’re sweating and going in the water, the sunscreen film can get broken so it makes sense to reapply.  

It is probably not necessary to reapply if you are just going to be indoors however. Sunscreen is pretty stable when not exposed to UV light and even then the sunscreens are stable. Zinc oxide certainly isn’t going to stop working.  So, I don’t think you really need to worry about reapplying sunscreen if you are just going to be indoors. I highly doubt you will notice any difference especially if you are in a standard office building and don’t have any exposure to UV light.

Question 2
Ayu asks – What is the science behind the claim that Vitamin E and Ferulic Acid stabilize Vitamin C (L-ascorbic Acid)? And is there ever a shelf-stable formulation of L-ascorbic Acid?

There was a paper published in the Journal of Investigative Dermatology in 2005 titled “Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin.” It claimed that a 15% solution of Vitamin C and a 1% solution of Vitamin E were stabilized and the photoprotection of skin was improved by adding 0.5% Ferulic acid. They showed some interesting results when the product was applied to the skin of weanling white Yorkshire pigs. Animals that got the treatment the combination of three antioxidants experienced less sun burn than animals that didn’t. So, there is some synergistic effect with ferulic acid and Vitamin C+E. 

Unfortunately, this doesn’t mean that products on the market with these three ingredients in them are more shelf stable. It wasn’t clear but the researchers likely made the solutions right away and applied them to the test subjects. Any product that you can buy in the store has been sitting for a number of weeks or maybe even months. By the time you get it, the Vitamin C no doubt will have broken down and the fact that Ferulic acid is in there probably won’t have much impact. There are companies that claim they have shelf stable l-ascorbic acid formulations but I’m skeptical. Especially if the product has water in it and is not in an opaque container. Both water and UV exposure can break down ascorbic acid. In fact, I read in one paper in the November 2019 issue of Food chemistry that showed a significant amount of vitamin C broke down within 1 hour of making the aqueous solution. 

Question 3

Vampire facials and using your blood in creams… Is this really a good thing? No, it’s a terrible idea. It’s unregulated and potentially dangerous.

Question 4

Recycling – from your episode with Sarah a while back I got the impression that recycling isn’t that common in the States. Here in the UK we recycle everything, it’s ingrained into us to recycle as much as possible. And when you both mentioned paper straws on holiday this has been the case for a while in the UK, it’s been widely accepted. I just wondered if the cultures are very different.  

I think the difference is just based on the cultural norms of where you are. Recycling is done more in some places, less in others. In Chicago, we don’t really have a good recycling program. Unfortunately, even the stuff that is recycled is often not getting recycled. It used to be that China would take garbage and sort it for recycling. But these days, that doesn’t happen much. So all those shampoo bottles and skin lotion containers mostly just end up in landfills (at least in the US). 

Question 5

Products like revitalash- eyelash growth serums, how do they work, what is the magic ingredient? Is this a good long term solution? The story behind how this brand came about is incredibly touching but could it really be recommended to those not in surgery? 

We covered eyelash growth products way back in episode 149. The quick answer is the only one that is approved (and proven) to work is the product from Allergan called Latise. 

Question 6

What is your opinion on cosmetician brands as opposed to the big beauty brands? For example DCL, skinceuticals, zelens Vs Estée Lauder, clarins, elemis etc. – With big company brands you will find products that will work for most people. Cosmetician brands are more niche targeted so there might be some consumers who like them more but they might not appeal to a typical consumer. I always say when in doubt, stick with the big beauty brands. 

Question 7

Which other beauty or scientific podcasts do you listen to?

Fat Mascara
The Eco Well
The Skeptics Guide to the Universe
The Reality Check
Science for the People
Science Magazine podcast
Mintel Little Conversations

Question 8

What are the latest advancements in cosmetic technology? I know 2019 was a trend year of retinol and biomes, what else are scientists working on? What are the big cosmetic brand scientists working on?
Sustainability
New anti-aging actives
Stabilizing ingredients
New preservatives

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{ 2 comments… add one }
  • fiona January 23, 2020, 1:43 pm

    I used to read your blog every day….until you moved to podcasts. As someone with hearing issues, this doesn’t work for me. It seems the show notes are not always posted and when they are they are incomplete. Please go back to blogging instead of podcasting!

    • Perry Romanowski January 30, 2020, 7:57 am

      Thanks for the feedback Fiona. I’ll try to do a better job of posted the show notes.

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