Sun exposure guidelines for vitamin D may need to be revised
- The researchers used blood samples from 75 people to assess vitamin D levels against current sunlight guidelines, which scientists initially based on skin samples.
- Their results suggest that current sunshine guidelines may need to be revised.
- More calculations and research are needed before health experts can create new sunlight guidelines.
Vitamin D is a fat soluble vitamin that plays a vital role in human health. It gets better
Ultraviolet (UV) radiation from sunlight is a major source of vitamin D, accounting for approximately
Sunlight contains two types of UVRs: ultraviolet A (UVA), which makes up about 95% of the sun’s rays, and ultraviolet B (UVB), which makes up about 5% of the sun’s rays. Both UVA and UVB cause tanning, skin aging, and the development of skin cancer, but only UVB leads to the production of vitamin D.
The current sun exposure guidelines for vitamin D derive from
It’s important to update sunshine guidelines to make sure people are getting enough vitamin D while not putting themselves at risk for sunburn and skin cancer.
In a recent study, researchers at King’s College London (KCL) in the UK conducted a study to test current guidelines on vitamin D. They compared levels of serum 25-hydroxyvitamin D3 – the gold standard for assess vitamin D – in healthy volunteers after exposure to UV rays with levels suggested in current guidelines.
They found that current guidelines did not accurately predict vitamin D production from UV exposure. However, adjusting the vitamin D calculations could solve this problem.
“The old spectrum of vitamin D will work if we subtract 5 [nanometers (nm)]of each wavelength, so that the entire spectrum is shifted 5 nm to the left, ”said Professor Antony Young of Experimental Photobiology at KCL and lead author of the study. Medical News Today.
The study appears in PNAS.
Researchers recruited 75 healthy young volunteers during the winter and spring of 2011-2014, when ambient UVB levels were low and the skin obtained some protection from clothing.
Volunteers underwent full or partial body exposure to five different man-made UVR sources with varying levels of UVB radiation spectra on five occasions 3-4 days apart. Before, during and after exposure to each spectrum, the researchers measured their blood levels of vitamin D.
The team then used various statistical models to determine the relationship between UVR dose and blood levels of vitamin D, also known as the “spectrum of action.” They then compared this with the spectrum of action of pre-vitamin D3 used to create the current guidelines for sun exposure.
The researchers found that vitamin D blood levels after exposure to UV rays did not meet current suggested guidelines.
To explain their results, the researchers say that the spectra of action of cutaneous pre-vitamin D3 and serum vitamin D are likely to be different, as vitamin D3 breaks down before forming vitamin D, making it difficult for it to break down. spectroscopy to accurately predict vitamin D levels from the pre-vitamin. D3 alone.
“Pre-vitamin D is converted to vitamin D in the skin by heat and then enters the bloodstream,” Professor Young said. “It has to undergo two enzymatic steps before it becomes biologically functional. We used the gold standard to assess vitamin D status, which is 25-hydroxyvitamin D3.
“The original study looked at the pre-vitamin D in the skin which does not take into account the later stages of the process. We also used low exposure doses which are recommended for safer sun exposure. The higher the dose. UVR is higher, the more photochemistry occurs, possibly with different results. A comparison is a bit like comparing apples to oranges. All I can say here is that our data has more of biological and physiological relevance, ”he added.
The researchers added that there could also be an error in the spectrum of action of pre-vitamin D3. To test this, they gradually reduced the 1nm pre-vitamin D3 action spectrum to see how their results would change. They found that a 5nm shift, known as the “blue shift,” corrected the old model.
The researchers explained that before health experts can create new sunlight guidelines from these results, more calculations are needed.
“Revising the guidelines will take more work,” said Prof Young, “This is done by ‘weighting’ a given solar UVR spectrum with a biological function, each of which has its own wavelength dependence.”
“To give an example: the maximum UVB (at solar noon) content of solar UV is around 5%, but that 5% will cause around 85% of sunburns because UVB is much more effective than the 95% of solar UV rays. UVA causing sunburn. The amount of UVB in the sun depends on the height of the sun. So these calculations change from minute to minute, ”he added.
“Risk-benefit calculations need to be done with sunburn and vitamin D with our new spectrum,” he added. “This will tell us the safest time to be in the sun at any time of day, season or latitude. The good news is that vitamin D is produced at a much lower dose of UVR than [what]causes sunburn. Many people deliberately seek exposure to the sun for a tan.
To conclude, the researchers say that guidelines for sunlight based on levels of vitamin D in blood serum could include more accurate assessments of the risks and benefits of sun exposure compared to those based on levels. pre-vitamin D.
The team also states that the limitations of their study include a wide range of time periods in which volunteers have been exposed to radiation. They also mentioned that there was a lot of interpersonal variation, although they expected it in studies of vitamin D.
“What these authors did was expose humans to ultraviolet radiation containing multiple wavelengths and measuring 25-hydroxyvitamin D blood levels”, Michael F. Holick, MD, Ph.D., and professor of medicine, who was not involved in this research yet is the author of the research behind the current sunlight guidelines, said MNT, “They didn’t measure pre-vitamin D3 in the skin.”
In future work, researchers say they will perform risk-benefit calculations and model the effect of melatonin on different skin types. When asked what the main findings of the research were, Professor Young replied:
“I think the main message is that the doses of UVR for vitamin D production – and the sun is the main source – are much lower than for sunburn. Short periods of regular exposure will give you good vitamin D status.