Pesticide and Environmental Update
Heirloom
Tangerine Tomatoes Top Reds in
Preliminary Lycopene Study
 Tangerine
tomatoes, named for their attractive orange color, are plump, juicy, and
slightly sweeter than everyday red tomatoes. Sold seasonally at some
farmers’ markets and specialty grocers, these are heirloom fruits, the
kind that your grandparents or great-grandparents may have planted in
their garden.
Besides their appealing color and pleasing flavor,
there’s another reason to give these vintage tomatoes a try. A 1-month
study led by Agricultural Research Service chemist Betty J. Burri and
former ARS biologist Betty K. Ishida, both based in California, has
provided new evidence to suggest that, ounce for ounce, tangerine tomatoes
might be better sources of lycopene—a powerful antioxidant—than are
familiar red tomatoes.
The difference lies in the forms of lycopene that
the two tomato types provide. The trans-lycopene form makes up most of the
lycopene in common red tomatoes. In contrast, most of the lycopene in
tangerine tomatoes is tetra-cis-lycopene.
The California investigation and one conducted by
scientists in Ohio suggest that the tangerine tomato’s tetra-cis-lycopene
is more efficiently absorbed by our bodies than is the trans-lycopene of
red tomatoes.
For the California study, 21 healthy men and women
volunteers were asked not to eat any fresh tomatoes, tomato products, or
other foods rich in lycopene (watermelon or pink grapefruit, for example)
other than that provided by the researchers. That instruction went into
effect at the start of a 1-week “washout” period and stayed in effect
throughout the rest of the study period.
In the week after the washout, volunteers ate their
usual breakfast, dinner, and snacks (minus lycopene-rich foods), but came
to the ARS Western Human Nutrition Research Center in Davis, where Burri
is based, to have a special lunch. This meal consisted of kidney bean
chili made with either red or tangerine tomato sauce. The chili, about a
2-cup serving, was accompanied by French bread, butter, and a salad of
leafy greens with dressing.
Volunteers followed that regimen with another
week-long “no lycopene” washout stint before switching over to a final
1-week phase featuring lunches of whichever type of chili—red or
tangerine—they had not already eaten earlier in the study.
Blood was analyzed weekly for lycopene levels with a
standard laboratory instrument known as a “high-performance liquid
chromatograph.” The analyses indicated that lycopene levels increased
relative to those measured just before each 1-week chili regimen began.
Total lycopene levels increased more after the tangerine tomato treatment
than after the red tomato treatment.
The team also assessed oxidative damage. Lycopene
and other antioxidants can, as the term implies, protect cells and “good
fats”— essential fatty acids—against oxidation. Using a procedure
known as a “TBARS assay,” the scientists determined that oxidative
damage decreased with both treatments. But decreases were greater after
the tangerine-tomato regimen.
Burri and Ishida, along with former ARS visiting
scientist Jung S. Seo and others, published their findings in a 2009 issue
of the International Journal of Food Sciences and Nutrition.—By Marcia
Wood, Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS
national program (#107) described at www.nps.ars.usda.gov.
To reach the scientists named in this story, contact
Marcia Wood, USDA-ARS Information Staff, 5601 Sunnyside Ave., Beltsville,
MD 20705-5129; (301) 504-1662.
"Tangerine Tomatoes Top Reds in Preliminary
Lycopene Study" was published in the February 2011 issue of
Agricultural Research magazine.
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