Text 11660, 263 rader
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Ärende: Chocolate as Sunscreen
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From: /m <mike@barkto.com>


http://www.sciencenews.org/articles/20060610/food.asp

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As if you needed another reason to eat chocolate, German researchers have shown
that ingesting types rich in cocoa solids and flavonoids—dark chocolate—can
fight skin cancer. Their findings are preliminary because they come from a
trial of just 24 women who were recruited to add cocoa to their breakfasts
every day for about 3 months.

Half the women drank hot cocoa containing a hefty dose of flavonoids, natural
plant-based antioxidants that research has suggested prevent heart attacks. The
remaining volunteers got cocoa that looked and tasted the same but that had
relatively little of the flavonoids. At the beginning and end of the trial,
Wilhelm Stahl of Heinrich-Heine University in Düsseldorf and his colleagues
conducted a host of tests on each volunteer. One assessment involved
irradiating each woman's skin with slightly more ultraviolet (UV) light than
had turned her skin red before the trial began.

The skin of the women who had received the flavonoid-rich cocoa did not redden
nearly as much as did the skin of recruits who had drunk the flavonoid-poor
beverage. Women getting the abundant flavonoids also had skin that was smoother
and moister than that of the other women.

Overexposure to UV light can foster the development of skin cancer. A dietary
source of skin protection might offer some innate defense for sunny days when
an individual doesn't use sunscreen, Stahl's team says.

Why chocolate?

Chocolate, these scientists note, is just the latest in a range of
antioxidant-rich foods holding the potential to shield skin from sun damage.
For nearly a decade, Stahl's group has conducted studies with cooked tomato
products showing that their ingestion, too, can limit UV-induced skin
reddening. Pigmented molecules called carotenoids—especially the one known as
lycopene—appeared responsible for tomato's skin-protection benefit (see Dietary
protection against sunburn (with recipe)
http://www.sciencenews.org/articles/20010526/food.asp ).

Many of the carotenoids in tomatoes are powerful antioxidants that can quash
free radicals. These are the molecular fragments that can cause biological
havoc when they rip electrons from other molecules. Because many flavonoids
also function as potent antioxidants, Stahl's team decided to investigate
whether substances in chocolate might offer skin protection.

The researchers recruited women between the ages of 18 and 65. Each volunteer
received packets of a dry powder to mix each day with 100 milliliters of hot
water—roughly a half cup. Half of the women received powder containing 329
milligrams of flavanols, a type of flavonoid, per serving. The rest got powder
delivering a mere 27 mg of flavanols per serving. The primary flavanols were
epicatechin and catechin.

Mars Inc., the candy company that has been experimenting with dark-chocolate
products rich in flavonoids, supplied the cocoa powder and partially funded the
experiment. Harold H. Schmitz, the company's chief science officer, claims that
the proprietary recipe for the product retains nearly all of the natural-cocoa
flavonoids that most chocolate processing cooks and washes out.

In the June Journal of Nutrition, Stahl's team reports that the women drinking
the high-flavonoid cocoa had 15 percent less skin reddening from UV light after
6 weeks of cocoa consumption and 25 percent less after 12 weeks of the trial.
Both figures are comparisons with the same women's response to UV light before
the study started. The women drinking the cocoa with low flavonoids showed no
change during the trial.

Most flavonoids absorb UV light, and this probably played a role in the skin
effect, the researchers say. However, they add, skin reddening is also an
inflammatory response, and other researchers have linked consumption of
flavonoids to ratcheting down the body's synthesis of inflammatory agents.

For the women getting larger doses of flavonoids, blood flow in the skin
doubled over the course of the trial in tissue 1 millimeter below the surface,
and increased by 37.5 percent in tissue 7 to 8 mm deep. Similar improvements in
blood flow through big blood vessels have been witnessed after people have
eaten dark chocolate (see Cardiovascular Showdown—Chocolate vs. Coffee
http://www.sciencenews.org/articles/20040529/food.asp ).

Moreover, after 12 weeks of consuming the flavanol-rich cocoa, the women's skin
was 16 percent denser, 11 percent thicker, 13 percent moister, 30 percent less
rough, and 42 percent less scaly than it was at the beginning of the
experiment. Although the mechanism for most of these benefits remains unclear,
the Düsseldorf researchers suspect that improved blood flow was a contributor.

Mars' Schmitz agrees. "People don't think about it, but in reality your skin,
just like every other tissue, depends on healthy blood flow. And in our
previous work ... we showed that blood flow in the extremities—the finger
tip—was improved" in people receiving cocoa flavonoids. So, he argues, "it
wasn't a shot in the dark" to hypothesize that cocoa ingestion might improve
overall skin condition and health. Yet, he adds, "I was still surprised to see
this."

If follow-up studies confirm these skin-health data, he says, "you're talking
about being able to make people look better." He adds, "We did not go into this
study with the intention to create a skin-health product, but it now looks like
maybe we've got one."

Not just any chocolate

Could a person realistically add enough flavonoids to his or her diet to
produce the benefits suggested by the study? Flavonoid quantities in the richer
cocoa were "similar to those found in 100 grams [a little over 3 ounces] of
dark chocolate," Stahl's group reports.

The cocoa drink provided its flavonoids in a serving that delivered only about
50 calories—far below the 400 to 500 calories ordinarily encountered in candy
providing a walloping dose of flavanols. Schmitz concludes that people can, in
theory, get this efficacious dose without blimping out.

The rub is that the cocoa used in this study and in others by Mars isn't
commercially available. If enough people pester the company for the cocoa,
Schmitz says, "eventually we might have to offer such a product." In the
meantime, he notes, the company offers a candy, CocoaVia, in flavanol-rich
portions that deliver fewer than 100 calories per serving. Targeting free
radicals and more

The new skin-protection data are more than a curiosity, says Hasan Mukhtar,
director of dermatology research at the University of Wisconsin–Madison. The
results suggest, he says, that dietary flavonoids reach the upper layers of
skin and "have the ability to counteract the oxygen free radicals generated as
a consequence of exposure to UV radiation."

UV exposure leads not only to impaired immunity and accelerated aging in skin,
but also to cancer, especially in light-skinned people, Mukhtar points out.
Work by his group and others has shown that UV light triggers many reactions in
the body that can lead to tissue damage.

In several papers, Mukhtar and his colleagues have found evidence that natural
botanical antioxidants—such as those just tested in cocoa—can inhibit harmful,
UV-triggered chemical pathways in the body.

In a study at the Case Western Reserve University School of Medicine, Mukhtar's
group applied epicatechin-rich green-tea flavonoids to the skin of volunteers
before irradiating the area with UV light. The researchers found that compared
with the response of unprotected skin, the tea cut by 60 to 80 percent DNA
changes known to play a role in immune suppression and skin cancer. The team
noted that the treatment also prevented sunburn.

In the March-April Photochemistry and Photobiology, Mukhtar's team reports the
results of treating cultured skin cells with pomegranate fruit extract, a
substance rich in flavonoids. When irradiated with UV-light in a test tube,
human cells in such an experiment usually undergo stress-induced inflammatory
changes that can lead to cancer. However, the pomegranate extract dramatically
inhibited those pre-carcinogenic changes.

Mukhtar points out that such data show that "not all of these agents affect the
same signaling pathways." This suggests, he says, that eating a mix of
flavonoid-rich foods may reinforce the UV protection by simultaneously acting
on several potentially damaging processes. Some flavonoid treatments may even
prove additive in their skin-protecting role, he says.

Chocolate's agents might offer important backup protection to some of the
substances his group has been testing, says Mukhtar.

However, diet isn't the only means of getting these protective agents to the
tissues that need them, Mukhtar suspects. He says it may make sense to add them
to skin-care products.

That said, I'd prefer to get my protection from eating dark chocolate. Indeed,
I look for any excuse to label as therapeutic my bittersweet indulgence.

References:

Afaq, F., . . . and H. Mukhtar. 2005. Pomegranate fruit extract modulates
UVB-mediated phosphorylation of mitogen activated protein kinases and
activation of nuclear factor kappa B in normal human epidermal keratinocytes.
Photochemistry and Photobiology 81(January-February):38-45. Abstract available
at http://dx.doi.org/10.1562/2004-08-06-RA-264.1. Preprint available at
http://phot.allenpress.com/pdfserv/10.1562%2F2004-08-06-RA-264.

Elmets, C.A., . . . and H. Mukhtar. 2001. Cutaneous photoprotection from
ultraviolet injury by green tea polyphenols. Journal of the American Academy of
Dermatology 44(March):425-432. Abstract available at
http://dx.doi.org/10.1067/mjd.2001.112919.

Heinrich, U., . . . and W. Stahl. 2006. Long-term ingestion of high flavanol
cocoa provides photoprotection against UV-induced erythema and improves skin
condition in women. Journal of Nutrition 136(June):1565-1569. Abstract
available at http://jn.nutrition.org/cgi/content/abstract/136/6/1565.

Katiyar, S.K., A. Perez, and H. Mukhtar. 2000. Green tea polyphenol treatment
to human skin prevents formation of ultraviolet light B-induced pyrimidine
dimers in DNA. Clinical Cancer Research 6(October):3864-3869. Available at
http://clincancerres.aacrjournals.org/cgi/content/full/6/10/3864.

Malik, A., . . . and H. Mukhtar. 2005. Pomegranate fruit juice for
chemoprevention and chemotherapy of prostate cancer. Proceedings of the
National Academy of Sciences 102(Oct. 11):14813-14818. Available at
http://www.pnas.org/cgi/content/full/102/41/14813.

Mukhtar, H. 2003. Eat plenty of green leafy vegetables for photoprotection:
Emerging evidence. Journal of Investigative Dermatology 121(August):viii-viii.
Available at http://www.nature.com/jid/journal/v121/n2/full/5601868a.html.

Syed, D.N., . . . and H. Mukhtar. 2006. Photochemopreventive effect of
pomegranate fruit extract on UVA-mediated activation of cellular pathways in
normal human epidermal keratinocytes. Photochemistry and Photobiology
82(March-April): 398-405. Abstract available at
http://dx.doi.org/10.1562/2005-06-23-RA-589.

Further Readings:

Harder, B. 2005. Can chocolate fight diabetes, too? Science News Online (Aug.
13). Available at
http://www.sciencenews.org/articles/20050813/food.asp.

Raloff, J. 2006. Prescription strength chocolate, revisited. Science News
Online (Feb. 25). Available at
http://www.sciencenews.org/articles/20060225/food.asp.

______. 2005. Leaden chocolates. Science News Online (Nov. 5). Available at
http://www.sciencenews.org/articles/20051105/food.asp.

______. 2005. Food colorings. Science News 167(Jan. 8):27-29. Available at
http://www.sciencenews.org/articles/20050108/bob9.asp.

______. 2004. Cardiovascular showdown—Chocolate vs. coffee. Science News Online
(May 29). Available at
http://www.sciencenews.org/articles/20040529/food.asp.

______. 2001. Dietary protection against sunburn (with recipe). Science News
Online (May 26). Available at
http://www.sciencenews.org/articles/20010526/food.asp.

______. 2000. Chocolate hearts. Science News 157(March 18):188-189. Available
at http://www.sciencenews.org/articles/20000318/bob10.asp.

______. 2000. Chocolate therapies (with recipe for Janet's chocolate medicinal
mousse pie). Science News Online (March 18). Available at
http://www.sciencenews.org/articles/20000318/food.asp.

______. 1997. Looking for lycopene? Tomatoes are okay, but . . . Science News
Online (July 19). Available at
http://www.sciencenews.org/pages/sn_arc97/7_19_97/food.htm.

Sources:

Hasan Mukhtar
Department of Dermatology
University of Wisconsin, Madison
Medical Sciences Center, Room B-25
1300 University Avenue
Madison, WI 53706

Harold H. Schmitz
Analytical and Applied Sciences
Mars Inc.
800 High Street
Hackettstown, NJ 07840


Wilhelm Stahl
Heinrich-Heine-Universität Düsseldorf Institute for Biochemistry and Molecular
Biology Universitätstrasse 1
40225 Düsseldorf
Germany
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 /m

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