This post is sponsored by Grant Industries. Silicones are one of the Big Bad ingredients in skincare, make-up and haircare. They’ve been demonised by natural brands, and there are more warnings about them than you can count. So I was delighted when Grant Industries (ingredient manufacturer, maker of Granactive Retinoid, physical sunscreens and of course, silicones) asked me to do a …
You’ve probably seen the recent influx of articles about the new FDA sunscreen study, usually titled something like “sunscreens can make it to your bloodstream!” The study itself is fine and good and necessary as a first step in the FDA’s new zeal for sunscreen regulation. But the more I read the coverage around it, the more annoyed I get, …
I’ve made a new video about antioxidants in skincare – it’s based on this post from a while ago: Antioxidants in Skincare: What Do They Do? In the video, I talk about: What free radicals are How they’re linked to skin damage Where free radicals come from How antioxidants work Which antioxidant ingredients have been studied in clinical trials Tips on …
I’ve posted a new video on vitamin D and sun exposure. Like most skincare addicts I’ve long thought that the sun was evil and should be avoided at all costs, but it turns out that’s an outdated viewpoint! Vitamin D is important for pretty much everything in your body, and a lot of people are deficient in vitamin D. Does sunscreen …
Supplements are one of the big new “it” categories in beauty, and collagen supplements are one of the most popular. Oral collagen supplements are supposed to be anti-aging, get rid of wrinkles and plump up skin so it looks younger. What’s the science behind them and do they really work?
I made a video on the topic! In it I talk about the way collagen supplements could theoretically work, and then break down the clinical studies on eating and drinking collagen.
Gio of Beautiful With Brains suggested that I do a post on this after an Instagram conversation about SPF, and how it doesn’t actually tell you how much longer you can stay in the sun without burning. So what exactly does a sunscreen’s SPF mean in terms of sun protection?
I’ve touched on this topic a few times in my other posts on sunscreen like How SPF Changes With How Much Sunscreen You Use and my video on Why DIY Sunscreen Doesn’t Work, but I’ve never tackled it directly before. So here it is!
SPF testing of sunscreens is performed on actual human volunteers in a laboratory. The sunscreen is applied at 2 mg per cm2 (equivalent to around ¼ teaspoon for the face, or a shotglass full for the entire body). A UV lamp is shone on bare skin and sunscreened skin, and the times required for redness (erythema) to show up are fed into this formula to work out SPF:
(MED stands for minimum erythemal dose, i.e. how much UV was required for red sunburn to occur.)
For example, if a volunteer normally gets burned in 5 minutes under the lamp, a sunscreen that stops them from burning for 75 minutes (15 times longer) would be classified as SPF 15:
(There’s ongoing research to replace this into an in vitro test that doesn’t require exposing people to cancer-causing UV rays, but right now they’re not reliable enough.)
So SPF means how many times more UV your skin can handle before burning with sunscreen on, compared to nothing at all.
Here’s a new video on why DIY sunscreen doesn’t work. It’s a much more detailed version of my post on DIY sunscreen from a while ago. It’s a topic that’s quite important to me, since it’s one of those cases where having the wrong information can cause serious harm!
This video has been a bit delayed due to the rest of my life getting a bit hectic, but I managed to get it out before the Northern Hemisphere summer finished, so go me…
I bought a lapel microphone and some new editing software, so everything is a bit more polished I hope! Check it out here.
Since I know there are a lot of nerds out there who like references and extra information, here are some of the sources for specific things I mention in the video (I got lazy with my citation style, sorry):
Skin cancer stats are sourced from the Cancer Council Australia and the Skin Cancer Foundation, who list the original sources at the bottom of their respective sites.
SPF testing guidelines: FDA (USA), TGA (Australia), EC (EU).
Dangers of UVA: Blog Post: Why You Should Protect Yourself From UVA
More info on sunscreen formulation
Sunscreens are very unlikely to cause endocrine disruption in practice: Journal of the American Academy of Dermatology (open access – quote: “Mathematic modeling indicated that it would take 277 years using a sunscreen containing 6% oxybenzone used at 2 mg/cm2 (the dose recommended for sun-protection factor [SPF] testing by the FDA) or 1 mg/cm2 (reported real-life use) to achieve the systemic levels of oxybenzone achieved in the study in rats”), Australasian Journal of Dermatology (looks at other filters apart from oxybenzone)
Nanoparticles in sunscreens are safe: TGA Literature Review (very comprehensive)
More (open access!) papers on zinc oxide: Nanotechnology Science and Applications, Science and Technology of Advanced Materials
People stay in the sun for longer when wearing sunscreen: JID paper (open access)
Reporting illegal medicines: FDA report form, TGA report form
This is a topic that I thought deserved a longer write-up.
It’s pretty obvious that psychological stress impacts on your physical health and skin, but exactly how they’re linked isn’t well understood. “Stress” is a bit vague and difficult to measure. But there’s more and more research on how stress impacts your body, and how reducing stress can help.
A small amount of stress can actually be a good thing. Humans have evolved over thousands of years to become quite adept at dealing with short-term acute stress, like escaping from alligators and mammoths. As part of our adaptation, a lot of our bodily functions actually perform better in periods of acute stress: your heart beats faster to transport more oxygen to your body, your liver products more glucose to fuel your muscles for a fight-or-flight response – your body essentially adjusts to give you the best chance of survival, and once you’re away from danger, your body can recover and replenish the stores it used up.
However, humans haven’t evolved to handle constant activation of the stress response. Late night emails, work deadlines, traffic jams and all the other irritating aspects of modern life contributes to a prolonged background of chronic stress. This leads to problems with your heart, immune system, digestive system, and of course, your skin as well.
Stress has been linked to flare-ups of psoriasis and atopic dermatitis, as well as breakouts. However, even if you don’t have these issues, your skin can still suffer when you’re stressed out!
Chronic stress decreases the amount of lipids your skin secretes. Remember the brick and mortar structure of your skin, where the dead outer layers (stratum corneum) consist of dead cell “bricks” with oily lipid “mortar” in between? The oily lipids are necessary to keep your skin flexible and hold in water. Additionally, your skin produces less of the proteins that hold your cells together (corneodesmosomes). These effects combine to make the skin less cohesive and more susceptible to damage.
