Sunday, May 12, 2013

Not All Sunlight is The Same

As a young child, I knew all along that I needed to spend some time in the sun daily to get vitamin D, which I knew is important for calcium absorption so I could grow taller. When my baby Elin was born, people advised me to sun-bathe Elin to reduce her jaundice and also to get vitamin D for bone growth and development. I was told to sun-bathe her in the morning, preferably before 8AM. I try to avoid midday sun and apply sunscreen when when the sun in high. I don't exactly know how sun can be harmful other than knowing that getting sunburn is not fun and overexposure of sun increases the risk for skin cancer. 

Then I learned something new. I learned that there are two main kinds of UV rays: UV-A, which is present from dawn to dusk all year round, and UV-B, which varies in strength depending on the height of the sun and is the only form of sunlight that produces vitamin D.

Sunlight and Vitamin D

Scientists have discovered that the body only makes vitamin D in the presence of UV-B rays. It is most intense when the sun is directly overhead, which normally occurs at midday. The rule of thumb is UV-B is most present when your shadow is at its "shortest." Although both UV-B and UV-A can damage skin and causes skin cancer, early morning and late afternoon sun exposes us to UV-A which has other negative health effects like cataracts, premature aging of skin, wrinkling, and loss of elasticity, while providing little vitamin DSo ideally, mid-morning sun is best as the presence of UV-B is strong enough for the body to make vitamin D with less risk of getting sunburn as compared to the midday sun. Note that UV-A can pass through glass, while UV-B can't - something important for people who sit in an office by the windows.

"UV-A penetrates more deeply into the skin than UV-B, due to its longer wavelength. Until recently, UV-A was not blocked by sunscreens. It is now considered to be a major contributor to the high incidence of non-melanoma skin cancers." (source)

Here in Singapore, we are blessed with UV-B exposure almost all year round. I bring Elin out to get some UV-B around 10AM daily. While a small amount of exposure to sunlight is healthy, too much can be dangerous. A short exposure to UV-B in mid-morning is probably better than longer exposure in early morning or late afternoon (even though you might avoid a sunburn, but you're not getting much vitamin D and might be causing your skin more long-term damage). It takes time for our body to absorb the vitamin D that is made in the oil on the surface of our skin. Thus, if you shower too quickly after sun exposure, you'll wash it away.

"It takes about 24 hours for UV-B-stimulated vitamin D to show up as maximum levels of vitamin D in the blood. Cholesterol-containing body oils are critical to this absorption process. Because the body needs 30-60 minutes to absorb these vitamin-D-containing oils, it is best to delay showering or bathing for one hour after exposure. The skin oils in which vitamin D is produced can also be removed by chlorine in swimming pools." (source)

Beautiful sunset in Bangka Island, Indonesia

Sunlight and Jaundice

When a newborn's liver is underdeveloped, the baby may experience jaundice because of excess bilirubin that the liver can't effectively eliminate. Elin had jaundice a few days after she was born and an advice I got was to sun-bathe her to break down the bilirubin (along with frequent feedings). I wasn't sure how the sun will help break down bilirubin. There are a lot of contradicting opinions whether sun helps to reduce jaundice level. I did come across an article that explained that biliblanket, a portable phototherapy used in homes to treat newborn's jaundice, uses the same type of light found in sunlight. But it's important to note that sun-bathing a newborn is not as safe as using a biliblanket because it doesn't filter out harmful UV radiation and infrared energy. As such please consult your pediatrician about this and take extra care when you choose to sun-bathe a newborn. 

Sun Protection

Protect your skin when you are planning to spend a lot of time in the sun and stay out just until your skin starts to turn "pink." Don't buy conventional sunscreens just because they are cheaper as they generally contain toxic ingredients that will damage our skin. High SPF doesn't mean it's better. Sunscreens that you buy over the counter generally only protects against the necessary UV-B rays and do not block the damaging UV-A rays. You can either make your own sunscreen or buy good quality sunscreens that have been rated by EWG Skin Deep. I personally recommend this natural sunscreen by Badger. Oh, and don't forget to eat food that are high in antioxidants, such as berries, prunes, raisins, and deep colored vegetables. They help to protect our skin from radiation received from the sun.

This is a very good post to read about the importance of vitamin D and what happens if we don't have enough of it.

What is your favorite brand of sunscreen? 

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