by Kathleen Scalise
If you're plagued by bad skin and live in the city, the culprit is likely air pollution, according to a new Berkeley study. It found ozone rapidly strips vitamin E, an important component of healthy skin, from the uppermost skin layer.
"This is not what we expected to find," said Berkeley researcher Jens Thiele. "It was very striking how readily vitamin E was depleted."
Skin conditions reportedly aggravated in urban environments include atopic dermatitis, psoriasis and other ailments which generate itchy, red, inflamed and scaly skin, said Thiele.
Medical studies have repeatedly indicated that in urban air-polluted areas, such skin problems increase. The new findings suggest an explanation for why this may happen.
Findings were presented Feb. 26 at a meeting of distinguished scientists working on the biology of oxidants -- the Oxygen Club of California.
Berkeley researchers working on the study were Thiele, Professor Lester Packer and researcher Maret Traber.
The researchers examined a thin layer at the surface of the skin called the "stratum corneum."
Long considered an inert layer of "dead" skin, the stratum corneum is now receiving considerable attention as the gateway to underlying body tissues.
"Everything you apply on the skin has to pass through that layer," said Thiele.
After exposure for two hours to ozone levels up to twice those of peak times for heavily polluted regions such as Mexico City or Los Angeles, vitamin E content in the stratum corneum plunged by 25 percent, the researchers found. After a similar brief exposure for six consecutive days, only about a quarter of the original vitamin E survived.
Although the ozone level used in the experiments was double what might be encountered in the worst real-world conditions, "the point is we only exposed the skin for two hours," said Thiele. "In the real world, it's really much more of a chronic exposure."
Ozone concentrations peak daily between noon and early afternoon. Mexico City has the highest ozone levels in the world, while Los Angeles leads in the U.S.
Vitamin E is a fat-soluble compound found in some plant oils and the leaves of green vegetables. It acts as an inhibitor of oxidation processes in body tissues and has long been a folk remedy for skin ailments. The new research underscores the efficacy of vitamin E.
Thiele puts forward two possible mechanisms to explain why depletion of vitamin E in the stratum corneum could cause flare up of these conditions.
In both explanations, the absence of vitamin E leads to oxidation and degradation of important skin fat molecules called lipids, composed of ceramides cholesterols and unsaturated fatty acids.
Possibly the destruction of "barrier lipids" that regulate the movement of materials in and out of the skin is responsible.
Or perhaps the increased formation of harmful chemicals from the breakdown of the lipids triggers inflammatory responses in underlying skin layers.
Key to the experiment was a new test method developed to collect skin samples from the very thin stratum corneum.
The principle of the new test is simple: apply a strip of tape to the skin and remove it.
"You can do it yourself," said Thiele. "Remove the tape and you'll see something on it. That's your stratum corneum."