Most replayed moment: How to Balance Sunlight and Suncream | Professor John McGrath

**SPEAKER_1** (0:01)
Hello, and welcome to ZOE Recap, where each week, we find the best bits from one of our podcast episodes to help you improve your health.
Today, we're talking about skin and sunlight. Skin and sunlight have a complicated relationship. Sunlight helps our bodies produce vitamin D, which is essential for overall health. However, too much exposure can accelerate skin aging and increase the risk of skin cancer. So how much sun is enough? Are most of us getting too little or too much? Where does sunscreen fit into a healthy daily routine? I'm joined by Professor John McGrath to explore how sunlight affects our skin and how to strike the perfect balance.
What's actually happening on the surface of my skin every day?

**John McGrath** (0:49)
Well, this amazing organ that you have, the skin. As an adult, you've got 1.8 square meters of amazing carpet, which we recognize as this barrier that keeps the outside out and the inside in, and also has its own appearances too.
It's a very dynamic structure. The outer layer of your skin is replacing itself every four weeks in reaction to the external environment. You really have to build up this barrier to protect yourself. It's rather amazing what skin can do in terms of its function. It's there not only to look nice, but it also protects you. It protects you against inflammation, against infection. It makes hormones, it makes vitamins, it has its own immune system. It's a fabulous organ. And so it's worth thinking about and worth preserving.
And of course, over the course of our lifetime, it does change a little bit. And sometimes it doesn't always work as well as it did in earlier life. But that's part of a natural process for this amazing organ, our skin.

**SPEAKER_1** (1:52)
What happens when sunlight hits our skin?

**John McGrath** (1:57)
So, sunlight, as we know, is composed of lots of different wavelengths, and these will penetrate the skin. Many of your listeners will have heard of UVA, UVB, UVC, visible light, and all of these will have different penetration capabilities through your skin. But ultimately, what they're doing is either causing damage to your genetic material, the DNA, or directly some of the structures and fibers in your skin.
So, it is an enemy on one level, but actually, in moderation, sunlight is good for you. There have been many epidemiological studies that show sunlight is really good for your heart.
So, cardiovascular health can be improved by sunlight exposure. So, that probably means next time you're not in the gym and you're lying on the beach and somebody phones you up and you say, just doing a bit of cardio. It actually may be telling the truth. So, dermatologists are always worried about DNA damage, about cancer, about molds turning malignant, what we call melanoma, and some other skin cancers. But there are other clinical and human health issues that are beneficial. We all feel good, of course, because of the endorphins that sunlight releases into our skin.

**SPEAKER_1** (3:12)
I was actually going to ask John, could you explain for a minute, how can sunlight be good for my heart? In fact, then I'd love you to explain how sunlight can make me feel good, because it definitely does.
What's going on?

**John McGrath** (3:22)
So let's take the skin part first of all. So when you shine sunlight on your skin, it is damaging the DNA in your skin. So tanning, I prefer the word DNA damaging. So you're actually damaging the DNA. When you have damaged DNA, it will produce a chemical, which we call POMC, Pro-Opio Melanocortin. Pro-Opio Melanocortin, POMC, is then broken down into various other subchemicals.
Some of which will stimulate the suntan, something called alpha melanocyte stimulating hormone. But one of the other breakdown products of POMC, believe it or not, is beta endorphins. So everybody knows about endorphins being a sort of stimulus to making us feel good, to feel better. Exercise can stimulate endorphins. Other things can stimulate your endorphins.
Sunlight can stimulate beta endorphin in the skin.
And maybe this is one reason why people like lying in the sun or going to tanning salons, because you're becoming almost a natural junkie with your endorphin release in the skin. And so that's why we feel good to some extent. In terms of your cardiovascular health, it's the chemistry and the science is much more deep than that. You're controlling inflammatory chemicals called nitric oxide and other destructive antioxidant quenching as well can be useful. We don't know it for sure, but from population studies, we know it's good for your heart. You can save a lot of lives from cardiac ill health by having sun exposure.