Updated: Oct 29
In some ways, you can think about safe sun protection similar to sex education. In other words, abstinence or avoiding the sun and photo sources is probably the only way to truly decrease the negative impact of UV exposure. However, the sun does have benefits as well that we have to balance. Barrier methods such as sunscreens, clothing, sunglasses, and hats are the clearest and most obvious methods to block UV, but they have their limitations. There is a world of antioxidants in photoprotection that can decrease the impact of UV damage on the skin. They are not perfect and should be combined with traditional sunscreen and sun-protective clothing. However, they can play an important role in sun safety. Read more...
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What are reactive oxygen species (ROS)?
Photoaging of the skin and photocarcinogenesis is defined by the impact of light, both visible light and ultraviolet light, on the skin through the creation of molecules that can damage our cells, the DNA of our cells, and proteins in our skin. Photoaging is considered premature aging of the skin secondary to light exposure while photocarcinogenesis is the development of changes in the cells of our skin that lend themselves to the development of cancer of the skin. The intermediates created by light exposure that impact our skin and its cells are what is referred to as ROS or reactive oxygen species.
The ROS impacts cells by activating cell pathways involved in cells both dividing and dying. ROS can also directly damage cells triggering an inflammatory response.
How does reactive oxygen species (ROS) impact the DNA of cells?
Reactive oxygen species affect the DNA of cells through a few different pathways.
The DNA of our cells can absorb UV light, UVB in particular. When UVB is absorbed by DNA, the energy of this light can directly damage our DNA leading to the risk of cancer development. UVB can also trigger the development of changes in our DNA that make our cells resistant to cell death leading them to continually divide. This also places our cells at risk of cancer development.
How does reactive oxygen species (ROS) trigger inflammation from UV exposure?
When our skin interacts with UV exposure, there is an increase in blood flow to the skin because our blood vessels dilate with the release of factors in our skin that trigger this. This vasodilation along with other factors brings in inflammatory cells. This will initially be felt as sensitivity, pain, and/or itching as well as seen as redness, swelling, and possible blistering. This can also result in a decrease in immunity or immunosuppression in the skin.
How does UV affect the extracellular matrix?
UV activates different factors in our skin that lead to decreased collagen synthesis amongst other changes.
How does infrared affect the skin?
IR can reach our subcutaneous tissue. Redness, mottled hyperpigmentation, broken blood vessels, decreased collagen, and increased development of new blood vessels.
How does visible light affect the skin?
Visible light can cause redness, heat damage, and ROS to develop which promotes indirect DNA damage in skin cells. These changes are similar to UV exposure.