If you want to see the skin-aging process in overdrive, look at the skin under the toxic influences of what is called extrinsic aging.
Health Care Center
UV radiation hits our skin in the form of damaging UVA and UVB rays. Try this mnemonic device to remember the difference—UVA for Aging and UVB for Bad Bum. UVB gives you the redness typical of a sunburn. The SPF, or sun protective factor number, of a sunscreen refers to its ability to block out UVB radiation. Most of the UVB is absorbed and eliminated at the epidermal layer, but not without causing some real problems first. It damages the DNA of the keratin-producing keratinocytes, markedly reducing the production of new DNA for several hours after exposure.
The DNA damage induced by UVB rays has been associated with an increased risk of various skin cancers.
UVA radiation is the real culprit in accelerating the visible signs of aging. Unlike UVB, which is mostly absorbed and eliminated at the epidermis, UVA passes through the epidermis to the dermis, where it runs amok. Even mild sun exposure, not enough to induce overt sunburn, can cause a massive increase in enzymes called matrix metalloproteinases (MMPs).
Any agent—sun, stress, air pollutants, poor diet, or otherwise—that can energize the enzymes responsible for cutting apart your collagen is not a good thing. To make matters worse, collagen production grinds to a halt and oxidative stress in the dermis is elevated when MMPs start working overtime. The end result is that our collagen becomes fragmented and disoriented.
You can think of normal collagen fiber strands as three ropes neatly wrapped around each other. This is not the case when the strands are subjected to oxidative stress and environmental damage. The collagen fibers become thinned out in certain areas, and partial deterioration is evident. They also start clumping together. The elastin starts to grow thicker. This may seem like a good thing, but more elastin is not necessarily better because it forms clumps and turns into a globular mess.
With repeated exposure come misguided attempts by enzymes to repair the dire situation, and these local patchwork repair efforts only worsen the structure of collagen and elastin. Blood flow diminishes overall, but in certain areas of the skin, blood flow appears to be closer to the surface because the skin has thinned out. This leads to areas of discoloration and a loss of a normal, youthful tone. Interestingly, even skin tone is the first major factor considered, after the absence of wrinkles, when people attempt to determine the chronological age of a third party.
Other Environmental Factors
In addition to UV dangers, other damaging environmental factors include but are not limited to smoking, air pollution, ozone exposure, and the electromagnetic frequencies generated by cell phones and smartphones—or as we call them, crockberries. Suffice it to say that any number of environmental factors are at play, and while UV exposure gets all the attention, it is by no means the whole story. For example, the interplay of nutrition and UV exposure has been garnering increased research support.
It is interesting to note that in the late 1960s, scientific journal articles referred to UV exposure as accounting for almost 100 percent of the nongenetic, external influences on the visible signs of aging. Then, when study after study showed that smoking induces facial wrinkling, the sun’s contribution to skin aging dropped to “more than 90” percent. Take into consideration the emerging studies we will discuss next, those related to disease, diet, job strain, mood state, and stress, and the sun’s contribution has been estimated at 80 percent and falling fast.