That means that common health recommendations given by authorities in many countries -- that sun exposure should be avoided for three to five hours around noon and postponed to the afternoon -- could be wrong and may even promote CMM.
This is in part because the action spectrum for CMM is likely to be centered at longer wavelengths than that of vitamin D generation. This is an update for my own personal knowledge as for many years I have advised people to avoid the sun from 10 a.m. to 2 p.m. if they were at risk of sunburn. Well it turns out that this is the case where a little bit of knowledge can actually be dangerous.
Cutaneous malignant melanoma (CMM) is the most serious form of skin cancer, accounting for about three-quarters of all skin cancer deaths.
New research now supports that while avoiding the sun at mid-day will decrease your risk of painful sunburn it will actually increase your cancer risk.
How can this be?
Though he was not an author of the study above, his research found the same findings: that going out in the sun at mid-day is best for your health.
“Our recommendation, this is based on work in England and Norway, and the United States, that the optimal time to be in the sun for vitamin D production is near to solar noon as possible. That would be between say 10:00am and 2:00pm.
The reason is two-fold.
First of all, you need a shorter exposure time because the UVB is more intense.
Now, the second reason is that when the sun goes down towards the horizon, the UVB is filtered out much more than the UVA. And it turns out that the long wave of ultraviolet called UVA, which runs from about 320 to 400 nanometers, is highly correlated with melanoma -- where the UVB is the one that produces the vitamin D, and that’s from 290 to 315 nanometers,” Dr. Grant explains.
This is truly a profound concept, and one that is just beginning to permeate through the mainstream media.
For instance, U.S. News & World Report featured an article on time in the sun, and in it Robyn Lucas, an epidemiologist at Australian National University, agreed with these findings.
“I believe we all need a little unprotected time in the sun during the middle hours of the day when the sun is at its highest and UV-B rays can penetrate the atmosphere,” she said.
So let me restate this crucial new information:
If you want to get out in the sun to maximize your vitamin D production, and minimize your risk of malignant melanoma, the middle of the day is the best time and safest time to go.
“Squamous cell carcinoma is linked to lifetime ultraviolet B irradiants, whereas melanoma is linked to lifetime UVA irradiants, or sporadic sun burning in youth and things like that,” Dr. Grant says. “And so dermatologists, by telling people to put on sunscreen and avoid the mid-day sun, were actually giving recommendations that led to increased melanoma. And it’s because they didn’t carefully look at the wavelength dependents related to melanoma. And so they just didn’t figure out that they were giving bad advice.”
Both UVA and UVB can cause tanning and burning, although UVB does so far more rapidly. UVA, however, penetrates your skin more deeply than UVB, and is thought to be a much more important factor in photoaging, wrinkles and skin cancers.
Going Out in the Sun Will Lower Your Cancer Risk … NOT Increase It
Getting about 2,000 IU to 4,000 IU a day of vitamin D can help you to reduce your cancer risk by up to 50 percent!
And according to Dr. Grant, about 30 percent of cancer deaths -- which amounts to 2 million worldwide and 200,000 in the United States -- could be prevented each year with higher levels of vitamin D.
However, most people only get 250-300 IU a day from their diet, so another source -- ideally the sun -- is essential.
How Long You Spend in the Sun is Also Critical
A common myth, aside from that of avoiding the mid-day sun, is that occasional exposure of your face and hands to sunlight is "sufficient" for obtaining healthy vitamin D levels. For most of us, this is an miserably inadequate exposure to move vitamin levels to the healthy range.
You need to expose large portions of your skin to the sun, and you need to do it for more than a few minutes.
In Caucasian skin, an equilibrium occurs within 20 minutes of ultraviolet exposure. It can take three to six times longer for darkly pigmented skin to reach the equilibrium concentration of skin vitamin D. So, bearing in mind that you need to gradually increase your time, starting in the spring, you should be aiming toward exposing large areas of your skin to the sun, anywhere from 20 minutes at a time to two hours at a time, depending on your skin type and environmental factors.
Longer exposures will be needed if sunbathing occurs at off-peak times for ultraviolet light (before 12 p.m. or after 3 p.m.) or at the beginning or end of the summer (April or September).
You’re probably wondering, now that fall and winter are approaching in the United States, what to do when it’s too cold for sun exposure.
In the winter months, if you’ve had your vitamin D levels tested and found them to be low, a vitamin D3 supplement (cholecalciferol), which is the type of vitamin D found naturally in foods like eggs, organ meats, animal fat, cod liver oil, and fish, can be used. Continue to have your vitamin D levels monitored during this time, though, so you don’t overdose.
To learn more about how to use sunlight for your health -- and the dangers of not getting enough -- keep an eye out for my new book, Dark Deception, which is coming out shortly.