Scientists have discovered that an extract of broccoli
sprouts protects the skin against the sun's harmful
That's not the same as calling the extract a sunscreen,
"This is not a sunscreen, because it does not
absorb the ultraviolet rays of the sun," explained
Dr. Paul Talalay, a professor of pharmacology and molecular
sciences at Johns Hopkins University School of Medicine
Exposure to ultraviolet or UV rays is the primary cause
of most skin cancers. The incidence of skin cancer in
the United States is on the rise as men and women who
had too many sunburns earlier in life get older and
develop the disease.
Talalay started working on skin cancer prevention about
25 years ago. "Cells contain an elaborate network
of protective genes that code for proteins that protect
against four principal injurious processes to which
all of our cells are exposed and which are the causes
of cancer, degenerative disease and aging," he
Those four processes are: oxidation; DNA damage; inflammation
and radiation, namely ultraviolet radiation.
The cells' protective system normally operates
at about one-third capacity, so the real question is
what would ramp up that system.
"Our strategy has been to find things that will
boost the system," Talalay explained. Broccoli,
in particular, has previously reported to have some
"We looked in vegetables, and it turned out they
had a rather large quantities of a compound that induced
this system, particularly in cruciferous vegetables
such as broccoli, cabbage, Brussels sprouts, et cetera,"
The compound, called sulforaphane, is found in broccoli
sprout extracts and was first identified by Talalay
and his colleagues more than 15 years ago. Sulforaphane
has been shown to inhibit tumor development in animals.
For this study, Talalay and his colleagues tested the
compound in both mice and humans.
The human experiments involved six healthy volunteers.
Each participant was exposed to UV radiation on two
circles on their back that were either treated or not
treated with different doses of broccoli extract.
The highest doses of the extract reduced UV-induced
redness and inflammation (erythema) by an average of
37 percent, although protection varied from 8 percent
to 78 percent.
"If you apply an extract of broccoli sprouts that
contains high levels of sulforaphane to regions of human
skin, you can protect them very substantially,"
Talalay said. "We believe, to the best of our knowledge,
that this is the first demonstration of protection against
a known human carcinogen in humans."
One expert was excited by the discovery.
"There is some interesting data here," said
Dr. Vijay Trisal, an assistant professor of surgical
oncology at the City of Hope Cancer Center, in Duarte,
Calif. "Sulforaphane compounds have been known
to boost the immune system locally. This has some basic
science behind it."
"The same thing happens with interferon, which
we use for melanoma. It boosts the natural killer cells,"
The findings do need to be replicated, Talalay noted.
"It's going to take a little while to work
out how this should be applied," Talalay said.
"We would need to have a preparation rich in sulforaphane
that would be easily absorbed through the skin, and
this is not yet a reality. But, since we're dealing
with a food, we're not dealing with anything likely
to have a toxicity."
The study is published in this week's issue of
the Proceedings of the National Academy of Sciences.
Talalay and a co-author are unpaid consultants to Brassica
Protection Products LLC (BPP), which licenses the technology
to produce broccoli sprouts. These two authors, along
Hopkins University, are equity owners in BPP.
Antony Talalay, son of Paul Talalay, is chief executive
officer of BPP.