health

Vitamin D deficiency: Are you getting enough sunshine to keep the body healthy?


The cholesterol charity Heart UK said: “Most of us don’t get enough vitamin D.” Spending some time outdoors in sunny weather will top up vitamin D levels, but staying in the sun too long can be dangerous. What’s the right balance? According to Heart UK, around one in five adults, and one in six children, don’t get enough vitamin D. From April until the end of September, “it’s possible to get enough vitamin D by spending time outdoors”.

But how long do you need to be outdoors for? The charity estimated around 20 to 30 minutes, but “the exact time isn’t known”.

Board-certified dermatologist Anne Marie McNeill explained how vitamin D is synthesised.

“When your skin is exposed to sunlight, it manufactures vitamin D,” she began.

“The sun’s ultraviolet B (UVB) rays interact with a protein called 7-DHC in the skin, converting it into vitamin D3, the active form of vitamin D.”

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For example, wearing an SPF 15 or higher sunscreen reduces the chance of melanoma by 50 percent.

“It has been proven on the molecular level that the sun’s ultraviolet (UV) light damages the skin’s cellular DNA, creating genetic mutations that can lead to skin cancer,” said McNeill.

Although sunscreen is designed to filter out the sun’s UVB radiation – the same wavelength needed to create vitamin D – some of the rays still reach the skin.

“No matter how much sunscreen you use or how high the SPF, some of the sun’s UV rays reach your skin,” McNeill emphasised.

To illustrate, SPF 50 filters out 98 percent of UVB rays whereas SPF 30 keeps out 97 percent, and SPF 15 filters out 93 percent.

“This leaves anywhere from two to seven percent of solar UVB reaching your skin,” said McNeill. “And that’s if you use them perfectly.”

For those who are adamant unprotected sun exposure is the best way to get adequate vitamin D levels, they recommended “no more than 10 to 15 minutes of exposure”.

In addition, this is said to be “two to three times a week, followed by good sun protection”.

“That minor amount of exposure produces all the vitamin D your body can muster,” said McNeill.

Any more than that and sun exposure “is giving you nothing but sun damage”.

McNeill is unwavering in her stance, though. “Even just those unprotected 10 or 15 minutes are way more than enough time to cause DNA damage,” she said.

“Every bit of this damage adds up throughout your lifetime, producing more and more genetic mutations that keep increasing your lifetime risk of skin cancer,” McNeill concluded.

Her advice? “You can acquire vitamin D from a combination of diet and supplements. Fatty fish such as salmon, mackerel and tuna are especially good sources.”





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