Sun Exposure - The good and the Bad
1. Vitamin D production - this begins when UV rays hit our skin, and then there are a series of reactions involving the kidneys and liver to make active form of Vitamin D. Note- aging, increased cutaneous fat, skin coverage from clothing, darker skin, liver or kidney issues, and sunscreen use all limit or impair Vitamin D production.
Vitamin D is very important! It preserves bone mass, regulates calcium absorption, regulates the immune system, and new research is implicating its role in mental health, cardiovascular disease, hormonal health, diabetes, and many other chronic conditions.
2. Mental health – Sunshine positively affects mood. Interestingly, keratinocytes in our skin produce beta endorphins (our ‘feel good’ neuropeptide) in response to UV light. It can actually create addiction (to tanning) in susceptible individuals. We also release serotonin - our happy hormone.
3. Cancer protection – A systematic review from 2013 found that chronic, non-burning sun exposure reduced risk of developing Non-Hodgkin’s lymphoma (NHL), breast, colorectal, and prostate cancers. Non-burning sun exposure also decreases melanoma risk (the most aggressive and invasive type of skin cancer.)
1. Melanoma risk – This is the most aggressive form of skin cancer. Although melanoma risk may be decreased with healthy sun exposure, the risk sky rockets with history of sun burns. For instance, the risk of melanoma doubles when you've had more than 5 sunburns. Risk also increases with total number of lifetime sunburns, especially blistering burns. This delayed consequence emphasizes the need to protect and educate children/teens. One of the best ways to do so is to be a good role model so don’t downplay or normalize sun burns. And of course, nag and force sunscreen on them.
2. Skin aging –Frequent, excessive UV radiation (a.k.a. sun burns) will contribute to wrinkles, sun spots, and overall sagging. If UV radiation is in excess (whatever that means for your skin type,) it is literally killing the cells in your skin and up-regulates inflammatory pathways.
3. Eye damage – Wear your shades because UV radiation can induce cataract formation and increase risk of macular degeneration.
The ozone layer in the stratosphere absorbs UV radiation from the sun but since it’s becoming increasingly depleted (thanks to human activity,) more UV radiation than ever before is reaching Earth. So yes, the sun is getting “stronger” – but only because we are losing our protective barrier.
A safe amount of sun exposure really depends on a lot of factors. Determine your Fitzpatrick skin type here and check the UV index on the weather network before going out. With prolonged sun exposure, use a broad-spectrum sunscreen (more on this topic soon) and take note that ~80% of UV rays pass through clouds so don’t let your guard down on overcast days. There are also certain drugs and herbs that make the skin more sensitive to UV radiation so ensure you’re informed of your medication side effects.
Bottomline with sunshine - common sense is required. Enjoy it. Get enough, but not too much.