Have you ever looked at the skin on the buttocks of a
90-year-old? Dr. Fayne Frey has. “It is beautiful,” said the dermatologist and
author of the book “The Skincare Hoax.” “There is very little pigment, there is
very little wrinkling, there are very few blood vessels.”
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Compare that to the skin on a nonagenarian’s face, where you’ll
likely see brown spots, scaliness, visible blood vessels, much more wrinkling,
and a generally sallow appearance.
Some signs of aging, namely fine lines, happen naturally over time.
But Frey said that as much as 80% of the skin changes, we associate with age
are actually caused by the sun’s ultraviolet rays. The best way to avoid them,
aside from staying indoors, in the shade or permanently covered up? Sunscreen.
Sunscreen’s ability to block sunburns and prevent skin cancer is
well known, but many dermatologists say it is also the best skin care product
for slowing signs of aging. Here is what to know about how UV rays cause the
skin to age and how sunscreen helps to minimize those effects.
How UV Rays damage the skin
There are two categories of ultraviolet light: A and B. UVB
wavelengths are shorter and primarily affect the top layer of the skin. UVA
rays are longer and can penetrate deeper (they can also travel through glass,
so don’t assume a window keeps you safe from sun damage).
Years of exposure to both UVA and UVB rays damages cells on the
top layer of the skin, called keratinocytes. When that happens, the skin starts
to look red, rough and scaly in patches — a condition called actinic keratosis.
“It is due to DNA mutations that occur specifically in the
keratinocytes, and they then proliferate and become abnormal,” said Dr. Lena
Von Schuckmann, a dermatologist and clinician researcher at the University of
Queensland in Australia. In some cases, actinic keratosis can become cancerous.
Below the keratinocytes are the melanocytes — the cells that
produce melanin and cause the skin to darken. UVA rays primarily activate these
cells, resulting in a suntan. (Sunburn is different; it’s caused by UVB rays
injuring the top layer of the skin.) With long-term UV exposure, the
melanocytes become damaged, resulting in permanent hyperpigmentation. These
brown spots are sometimes called sunspots, age spots, liver spots or their
technical name, solar lentigines.
Collagen and elastin, which keep the skin elastic and supple,
reside in the next layer down. UVA rays trigger the breakdown of those
proteins, causing wrinkles as the skin loses its elasticity, as well as the
thinning of skin, making blood vessels more visible.
There is no real way to boost collagen and elastin artificially
(there’s scant evidence for the power of supplements and creams), but cells
called fibroblasts do continue to make the proteins as you age, although
production slows down. As a result, some dermatologists say it may be possible
to reverse some signs of aging.
If you start using sunscreen early and consistently enough, “and
the fibroblast is still young enough or healthy enough to be able to produce
more collagen,” the appearance of wrinkles could diminish over time, said Dr.
Henry Lim, a dermatologist at Henry Ford Health and a former president of the
American Academy of Dermatology. The key is making sure collagen levels aren’t
depleted further by sun exposure while the cells work to replenish the protein.
But Von Schuckmann said the jury is still out: “We certainly
have studies to show that sunscreen used on a daily basis reduces skin aging.
Whether or not it reverses skin aging, that’s a little bit tricky to differentiate.”
How sunscreen prevents signs of aging
Sunscreen stops damage by blocking UV rays from reaching and penetrating
the skin. There are two types of sunscreen ingredients: mineral and chemical.
Mineral ingredients, namely zinc oxide and titanium dioxide, act
as a physical barrier, reflecting the ultraviolet light off the skin. (Our eyes
can detect that reflection of light, which is why these sunscreens appear to
leave a white cast.) Chemical ingredients — such as avobenzone, oxybenzone and
homosalate — absorb the UV rays. Both types of sunscreen can degrade or wash
off over time, so it’s important to reapply every two hours, and more
frequently if you’re swimming or sweating.
In general, sunscreens are more effective at stopping the
shorter UVB rays than the longer UVA rays. Sun protection factor, or SPF, only
refers to how well the sunscreen prevents a sunburn, meaning how well it blocks
UVB.
Frey said that just a few ingredients approved for use in the
United States — namely avobenzone, oxybenzone, zinc oxide and, to a lesser
degree, titanium dioxide — block UVA. To make sure a sunscreen provides UVA
protection, look for one with these ingredients, or check that it’s labeled
“broad spectrum,” which means that it stops the longer wavelengths from
penetrating. (Newer ingredients available in Europe are more effective against
UVA; some are in the pipeline for review by the Food and Drug Administration.)
When it comes to choosing the best sunscreen to prevent signs of
aging, Von Schuckmann advised looking for one that’s broad spectrum and SPF 50
or higher; whether it’s a chemical or mineral formulation doesn’t matter. The
most important thing, she added, is that it “actually goes onto the skin every
single morning.”
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