Quantcast
ZME Science
  • News
  • Environment
  • Health
  • Future
  • Space
  • Features
  • ZME & more
    • About
    • The Team
    • Advertise
    • Contribute
    • Our stance on climate change
    • Privacy Policy
    • Contact
No Result
View All Result
ZME Science

No Result
View All Result
ZME Science
Home Health

Revisiting sunlight exposure guidelines: balancing Vitamin D with skin cancer risks

Too little sunlight will make you Vitamin D deficient. Too much and you risk sunburns and skin cancer.

by Tibi Puiu
October 21, 2021
in Health, News
Share on FacebookShare on TwitterSubmit to Reddit
Image credits: Nick Page.

Our bodies need regular exposure to sunlight in order to synthesize optimal levels of Vitamin D, sometimes nicknamed the “sunshine vitamin”. At the same time, excessive and unprotected regular exposure to ultraviolet radiation (UVR) can significantly increase the risk of developing skin cancer.

In order to balance the two, there are public health guidelines on optimal sunlight exposure. However, a new study has found that these guidelines, based on three-decade-old research, may require a revisal in light of new findings.

A delicate balancing act

When the skin is exposed to the sun, the presence of UV rays triggers a biochemical reaction that transforms provitamin D3 (or 7-dehydrocholesterol) into previtamin D3, which then enters the bloodstream where it becomes converted to 25-hydroxyvitamin D3 by the liver, also known as 25(OH)D — it is this latter form of vitamin D that your doctor can measure when you take blood tests. Later, 25(OH)D is further broken down by the kidneys and other specialized tissues in the body into a biologically active form of vitamin D, which performs numerous important duties, including promoting bone health and immune function, regulating calcium and phosphorus levels, and much more.

The amount of Vitamin D produced for a given timeframe of sunlight exposure can vary greatly, depending on factors such as skin tone, location, time of the year (close to the equator there are more UVR frequencies that are involved in Vitamin D synthesis), time of day, whether or not there are sunscreen or skincare products applied on the skin, age, and air pollution.

For those with light skin or low melanin levels, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma — the three most common types of skin cancer, in this order — frequently occur in sun-exposed areas of the body, which suggests UV exposure may be to blame.

ALSO READ:  Scientists find a way to genetically modify cats that don't cause allergies

The most important UVR frequency band in Vitamin D synthesis is UVB, a shorter wavelength of ultraviolet radiation that has higher energy levels. UVB is also associated with sunburn, darkening, and thickening of the outer layer of the skin. Although it comprises only 5% of ultraviolet radiation, short-wavelength UVB radiation is responsible for over 80% of sunburns.

Three decades ago, scientists exposed human skin cells (ex vivo) to various UVB levels, finding for the first time an association between these short-wavelength rays and the production of Vitamin D in the human body. Ever since then, these findings have been used as the basis for official solar exposure guidelines, which advise sun exposure at least 3 times a week during daylight (between 10:00 A.M. and 3:00 P.M.) on 20%–30% of the body surface area for about 30 minutes per session.

But a new study from researchers at King’s College London suggests there’s a different relationship between UVB and Vitamin D, which may prompt the revision of current standards and guidelines.

The team of researchers measured blood vitamin D levels in 75 healthy young volunteers, before, during, and after partial or full-body exposure to five different artificial UVR sources with different amounts of UVB radiation. The goal was to find the sweet spot between the pros of solar exposure (Vitamin D synthesis) and the cons (risks of sunburn and skin cancer).

The Vitamin D levels were compared to those that would be predicted from the old ex vivo vitamin D research. This comparative analysis showed there were important discrepancies between the actual measurements in live subjects and the predicted values based on ex vivo lab tests.

ALSO READ:  MDMA's miserable comedowns may actually be caused by impurities, not the drug itself

“An improved action spectrum based on serum 25(OH)D3, rather than cutaneous previtamin D3, will result in more refined assessments of risks and benefits of solar exposure that should result in better public health advice,” the authors wrote in their study published in the Proceedings of the National Academy of Sciences.

The study is timely considering the Commission internationale de l’éclairage, the global technical committee that is in charge of setting UVR exposure standards will soon convene to discuss these findings and re-evaluate the wavelength dependency of Vitamin D.

ShareTweetShare
ADVERTISEMENT
ADVERTISEMENT
  • News
  • Environment
  • Health
  • Future
  • Space
  • Features
  • ZME & more

© 2007-2021 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • News
  • Environment
  • Health
  • Future
  • Space
  • Features
  • ZME & more
    • About
    • The Team
    • Advertise
    • Contribute
    • Our stance on climate change
    • Privacy Policy
    • Contact

© 2007-2021 ZME Science - Not exactly rocket science. All Rights Reserved.

Don’t you want to get smarter every day?

YES, sign me up!

Over 35,000 subscribers can’t be wrong. Don’t worry, we never spam. By signing up you agree to our privacy policy.