By Emily Caldwell

Turning up the heat on the red tomato during processing has the potential to
give the popular garden staple added disease-fighting power, Ohio State
University research suggests.
Scientists have found that lycopene molecules in tomatoes that are combined
with fat and subjected to intense heat during processing are restructured in
a way that appears to ease their transport into the bloodstream and tissue.
The tomato is the primary food source of lycopene, a naturally occurring
pigment linked to the prevention of cancer and other chronic diseases.

In its standard structure in the average red tomato, the lycopene molecule
is laid out in a linear configuration. That structure seems to hinder the
molecule?s absorption through intestinal walls and into the blood, said
Steven Schwartz, an investigator in Ohio State?s Comprehensive Cancer Center
and a professor of food science and technology at Ohio State.

Meanwhile, most of the lycopene that is found circulating in human blood is
configured in a bent molecular form. This means that either the human body
somehow transforms lycopene molecules through reactions that have yet to be
identified, or that the bent molecular structures of lycopene are much more
likely to be absorbed into the blood and transported to tissue ? a necessary
step in preventing disease.

Assuming the latter is true, Schwartz and colleagues have devised a way to
process red tomatoes ? the variety preferred by American consumers ? into a
sauce that contains bent molecular forms of lycopene. A clinical trial
conducted in collaboration with Steven Clinton, a medical oncologist and
physician scientist in Ohio State?s Comprehensive Cancer Center, showed that
people had more lycopene in their blood after eating the specially processed
sauce than they did after eating regular red tomato sauce.

Schwartz described the research yesterday (8/20) at the American Chemical
Society meeting in Philadelphia.

In the food science world, processing gets a bad rap for its tendency to
deplete vegetables of nutrients, change their color and often negatively
affect how they taste.

?Instead, here is a case where processing is positive in terms of enhancing
absorption of lycopene,? said Schwartz.

Lycopene belongs to a family of antioxidants called carotenoids, which give
certain fruits and vegetables their distinctive colors. Carotenoids?
antioxidant properties are associated with protecting cells and regulating
cell growth and death, all of which play a role in multiple disease
processes.

In its natural state, lycopene in a red tomato is in what is called an
all-trans configuration, characterized by its linear form. The molecular
structure of lycopene circulating in human blood is in what is called a
cis-isomer configuration, or a bent form. The chemical properties are the
same ? only the configuration differs.

?What we have found is we can take the red tomato molecular form of lycopene
and by processing it and heating it in combination with added oil, we can
change the shape of the molecule so it is configured in this bent form,?
Schwartz said.

Heat is essential to the process, but so is adding some fat, Schwartz said.
In previous work, he and colleagues determined that consuming fat and
carotenoids simultaneously improved absorption of lycopene and other
compounds, but the scientists weren?t sure exactly why.

When humans eat fats, or lipids, the body produces tiny droplets of fat
called lipid micelles during digestion that are easily taken up through the
intestinal wall and absorbed into the bloodstream.

Continuing research has led Schwartz to hypothesize that lycopene in its
linear form tends to stack and become crystallized, which lowers, but does
not eliminate, its absorption potential. But the bent forms of lycopene are
able to more easily find their way into the lipid micelles during digestion,
and increasing amounts of the antioxidant in that form are more likely to be
transported to the blood along with the fats.

Taking all this into consideration, the researchers processed red tomatoes
into two kinds of sauce: a sauce rich in cis-lycopene, the bent
configuration, and a sauce containing mostly all-trans-lycopene, the linear
form. Both sauces were flavored similarly and initially heated using the
same methods. Corn oil was added to both sauces as well. But the sauce
designed to produce lycopene in the bent molecular forms was subjected to a
second round of heating at 260 degrees Fahrenheit for 40 minutes. The
resulting sauce contained nine times more cis-isomers than the regularly
processed sauce.

Twelve people participated in a study of the sauces, and all ate both kinds
of sauce over the course of the study. After each meal, researchers took
samples of participants? blood seven times during the following 9 1/2 hours
to measure lycopene levels. The scientists used a special testing method to
analyze lycopene levels in the blood associated only with the tomato sauce
meal, avoiding any other possible sources of those compounds in the
bloodstream.

Research participants had a 55 percent increase in total lycopene absorption
after eating the specially processed sauce when compared to their lycopene
blood levels after eating the regular sauce. This finding reinforced the
expectation that the bent forms of lycopene are more easily absorbed into
human blood, Schwartz said.

Details of this study were first published in the British Journal of
Nutrition in 2007. Additional clinical trials are ongoing.

Schwartz said most currently available commercial products don?t contain the
bent forms of lycopene molecules. But he noted that some home cooking
practices might be able to produce the same results as the special
processing method he and colleagues designed.

?Some people like to cook tomato sauce for prolonged periods, sometimes
reheating it day after day, because it tastes better on the second and third
day. They add fat by using oil or meat, and that?s going to start to induce
cis-isomers of lycopene if fat is present and the cooking continues,?
Schwartz said. ?So it?s possible people could induce this process and
increase lycopene absorption by routine food preparation procedures, as
well.?

Much of this research is supported by the Ohio Agricultural Research and
Development Center Competitive Grants Program, the National Center of
Research Resources of the National Institutes of Health, the National Cancer
Institute, and the U.S. Department of Agriculture Initiative for Future
Agricultural & Food Systems.
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