Posted by Savneet Singh on Aug.03, 2010

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The role of sun and its ultra-violet rays is a little more complex than what we think, and it may also give us an insight how do we age. The sun acts sort of like one of the machines that shoots out tennis balls. But the sun’s tennis balls comes in form of ultra-violet rays that are torpedoed down to Earth. Now, one type of ultra-violet rays, UVC, is blocked by the atmosphere before it reaches us, so this type of UV has very little effect. The rays that constantly affect you are the UVB rays and the UVA rays. Blocking all kinds of rays is not possible. UVB rays are stopped at the topmost levels of the skin, but they still penetrate inside and cause burning and skin cancer. They cause tanning as well.

On the other hand, UVA rays penetrate deeply in the skin to cause burns, wrinkles and skin cancer. To top it off, sunlight also destroys the reserves of folic acid, also known as folate or vitamin B9. Folate is required by the body to replicate DNA properly. The rays can also damage the eyes.

The question here is how does sunlight cause damage? One way is through connective tissue breakdown. UV radiation cause the structural protein of our skin, collagen, to break down and disables our ability to repair damage. Another way sun age our skin is through the formation of free radicals, those aggressive charged compounds that damage cells and breakdown collagen as well. Free radicals can cause cancer by changing our DNA and preventing our body from repairing it. UV destroys the rungs of the DNA ladder so that the DNA ladder posts bind with one another. Still another way UV rays cause damage is by thinning the walls of surface blood vessels, leading to bruising, bleeding and appearance of blood vessels through the skin.

But, the flip side is that we also really need UV rays. Natural sunlight creates active vitamin D, which we need for bone health, since it helps to regulate calcium. It helps to ensure the proper function of the heart, nervous system, clotting process and immune system. That is significant because thousand of cancer deaths a year are linked to insufficient UVB exposure and subsequent deficiency of active vitamin D. UVB activates vitamin D from cholesterol. That is the reason why cholesterol levels go high in the winter. In winter there is not much sunlight, so you don’t have enough active vitamin D, therefore your body pumps up your cholesterol in the hope of converting as much as possible to active vitamin D. This serves as another example of an evolutionary trade off between procreation and higher levels of cholesterol. So how strong we look, can be felt by high LDL, cholesterol and consequent heart disease and stroke.

Also, have a look at this fact: if you have low level of UVB penetration, then you need more cholesterol, which can be more readily converted to vitamin D. In this setting of low sun exposure, a substance called Apo E4 rises to help create more cholesterol and subsequent vitamin D. Apo E4 elevations of cholesterol lead atherosclerosis and Alzheimer’s later in life. Those of us, whose ancestors lived in the areas with high UVB rays were not so plentiful evolved to have less melanin in our skin to allow all those UVB rays to get through, but if skin color is too light or too much sunlight enters the cells, then folate level plummet. Without protection from those nutrients, other neurological symptoms increase in people and their offspring are prone to neural tube defects.

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Posted under Health Alerts, Health Facts.