WHY SUNSCREEN IS IMPORTANT AND HOW IT WORKS
The weather is getting nicer, and thankfully we are able to spend more time outside. After this (extremely) long winter indoors due to Covid restrictions, I am really excited about hanging out in nature and breathe some fresh air.
Nice weather and sunlight means also that we can finally top up our vitamin D levels without the need of supplementation. This vitamin is an important nutrient that helps rebalancing the immune system, it is involved in bone metabolism and promotes skin health (read more here); hence we really want to achieve optimum levels. Can we still synthetise vitamin D if we apply sunscreen?
SUNSCREEN AND VITAMIN D
Sunscreen is the best tool that we have to prevent skin cancer, slow down photoaging (skin aging due to UV ray’s exposure) and avoid sunburn. UV rays (UVA=aging and UVB=burning) increase oxidative stress in the body promoting an imbalance between free radicals and antioxidants. This reaction increases DNA damage, inflammation, and disrupts collagen’s synthesis. Collagen is a protein that acts as a glue for the skin, keeping it elastic and plump. When collagen levels are impaired, the skin might look saggy and dry.
Over the years, many medical studies have tried to understand if the use of topical sun protection decreases vitamin D synthesis. Theoretically it does, but the reality is that we still synthetise enough to be able to reach healthy levels. Here is why: even if sunscreen acts against UVB rays (which are the same ones that trigger vitamin D synthesis), this is not a complete protection. An SPF15 can block around 93% of UVB rays, while an SPF30 could reach 97% and an SPF50 around 98%. A 2019 review confirms the beneficial use of sunscreen, stating that (at the time of writing) there is an extremely low risk of impaired vitamin D intake when using sun protection.
This should encourage us to spend time outdoors whenever possible, and expose our skin to the sun with sunscreen. To top up vitamin D levels even further, you can choose to consume foods like salmon, sardines, mushrooms, and eggs that have a small amount of the sunshine vitamin. Some processed foods are also fortified with it, make sure to read the nutritional label to find out more.
MINERAL VS CHEMICAL SUNSCREEN
There are 2 different types of sunscreen, chemical and mineral. The mineral one, usually has titanium dioxide or zinc oxide, which creates a physical barrier between the sun and the skin. This prevents the UV rays from penetrating the skin, although not all of them are blocked (as mentioned before).
The chemical type has oxybenzone, octocrylene or other similar ingredients, which allow the UV rays to penetrate the skin. Thanks to a chemical reaction, the rays are converted into heath, which is then dispersed. The problem with certain chemical sunscreens is that some of the active ingredients are absorbed into our bloodstream in levels higher than recommended. Although not all of them pose this risk, I would choose the mineral ones as a safer choice.
For adequate protection, the amount of sunscreen applied for the whole body, should be around 2 tablespoons (amount recommended by the NHS for an average adult). Also ensuring to follow the manufacturer instruction on how often to reapply sunscreen is particularly important. If not reapplied as instructed, its protection is compromised.
SUN PROTECTIVE FOODS
Although foods cannot replace topical sunscreen, they can be a great addition when consumed as part of a heathy diet. It seems that certain foods can increase the protection against UV rays. One possible mechanism, is by providing antioxidants, partially counteracting the UV ray’s oxidative stress. Another mechanism is based on the absorption of some UV rays by certain phytochemicals.
One of the most famous sun protecting nutrients is lycopene, found in red coloured fruit and vegetables like tomato, guava, and watermelon. In several human studies, consumption of lycopene rich foods over the course of 10 to 12 weeks, shows a reduction of skin redness and sunburn (erythema) due to sunbathing.
Beta carotene is another skin ally when it comes to sun exposure. It is the precursor of vitamin A and it is found in orange/yellow fruit and vegetables like sweet potatoes, carrots, butternut squash, pumpkins, apricots, and dark leafy greens. Its effects are dependent on the amount ingested and their frequency. A minimum of 7 weeks is necessary to see any results, hence following a diet rich in beta carotene foods long term, it is beneficial.
EGCG is a chemical compound found in green tea. Over the past 2 decades, research has investigated its role in contrasting the effects of UV radiation. EGCG seems to offer some protection against skin damage on keratinocytes and Langerhans cells (a type of macrophage) and decreases the likelihood of sunburn.
Do not reach for food supplements yet, prioritise whole foods unless advised by your medical practitioner.
SUN PROTECTIVE LIFESTYLE
What else can we do to stay safe?
On top of sunscreen and sun protective foods, a good idea is to stay in the shade during the hottest hours of the day (this is particularly important to avoid sunburning and sunstrokes). The use of hats and appropriate clothing can also mitigate harmful exposure reducing the chances of getting sunburns. You can also find UPF (ultraviolet protection factor) clothing up to 50+, especially helpful for vulnerable individuals. Sunglasses help to protect your eyes from irritation and burn, select a type that clearly state their protection against UV rays.
Try not to rely on just one method, a combination of SPF, foods, and lifestyle tips can ensure higher protection allowing you to enjoy a safer summer!
REFERENCES
Köpcke, W. and Krutmann, J. (2008), Protection from Sunburn with β‐Carotene—A Meta‐analysis†. Photochemistry and Photobiology, 84: 284-288. https://doi.org/10.1111/j.1751-1097.2007.00253.x.
Matta MK, Zusterzeel R, Pilli NR, et al. (2019). Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA. 321(21): pp.2082–2091. doi:10.1001/jama.2019.5586
Neale RE, Khan SR, Lucas RM, et al. (2019). The effect of sunscreen on vitamin D: a review. The British Journal of Dermatology, 181(5): pp.907-915. doi: 10.1111/bjd.17980. Epub 2019 Jul 9. PMID: 30945275.
NHS (2019). Sunscreen and sun safety. www.nhs.uk/live-well/healthy-body/sunscreen-and-sun-safety [Online].
Parrado, C. Philips, N. Gilaberte, Y. et al. (2018). Oral Photoprotection: Effective Agents and Potential Candidates. Frontiers in medicine, 5, pp.188. doi.org/10.3389/fmed.2018.00188.
Passeron, T. Bouillon, R. Callender, V. et al. (2019), Sunscreen photoprotection and vitamin D status. Br J Dermatol, 181: pp.916-931. doi.org/10.1111/bjd.17992.
Skin Cancer Foundation (2021). www.skincancer.org/blog/ask-the-expert-does-a-high-spf-protect-my-skin-better. [Online].
Stahl, W. Sies, H. (2012). β-Carotene and other carotenoids in protection from sunlight, The American Journal of Clinical Nutrition, 96, (5), pp.1179S–1184S, doi.org/10.3945/ajcn.112.034819.
Xu, Y., Zhu, J., Zhou, B., & Luo, D. (2012). Epigallocatechin-3-gallate decreases UVA-induced HPRT mutations in human skin fibroblasts accompanied by increased rates of senescence and apoptosis. Experimental and therapeutic medicine, 3(4), 625–630. https://doi.org/10.3892/etm.2012.466.
