Urbana, Illinios
January 16, 2007
A new
University of Illinois (U of
I) study shows that tomatoes and broccoli--two vegetables known
for their cancer-fighting qualities--are better at shrinking
prostate tumors when both are part of the daily diet than when
they're eaten alone.
"When tomatoes and broccoli are eaten together, we see an
additive effect. We think it's because different bioactive
compounds in each food work on different anti-cancer pathways,"
said University of Illinois food science and human nutrition
professor John Erdman.
In a study published in the January 15 issue of Cancer Research,
Erdman and doctoral candidate Kirstie Canene-Adams fed a diet
containing 10 percent tomato powder and 10 percent broccoli
powder to laboratory rats that had been implanted with prostate
cancer cells. The powders were made from whole foods so the
effects of eating the entire vegetable could be compared with
consuming individual parts of them as a nutritional supplement.
Other rats in the study received either tomato or broccoli
powder alone; or a supplemental dose of lycopene, the red
pigment in tomatoes thought to be the effective
cancer-preventive agent in tomatoes; or finasteride, a drug
prescribed for men with enlarged prostates. Another group of
rats was castrated.
After 22 weeks, the tumors were weighed. The tomato/broccoli
combo outperformed all other diets in shrinking prostate tumors.
Biopsies of tumors were evaluated at The Ohio State University,
confirming that tumor cells in the tomato/broccoli-fed rats were
not proliferating as rapidly. The only treatment that approached
the tomato/broccoli diet's level of effectiveness was
castration, said Erdman.
"As nutritionists, it was very exciting to compare this drastic
surgery to diet and see that tumor reduction was similar. Older
men with slow-growing prostate cancer who have chosen watchful
waiting over chemotherapy and radiation should seriously
consider altering their diets to include more tomatoes and
broccoli," said Canene-Adams.
How much tomato and broccoli should a 55-year-old man concerned
about prostate health eat in order to receive these benefits?
The scientists did some conversions.
"To get these effects, men should consume daily 1.4 cups of raw
broccoli and 2.5 cups of fresh tomato, or 1 cup of tomato sauce,
or half a cup of tomato paste. I think it's very doable for a
man to eat a cup and a half of broccoli per day or put broccoli
on a pizza with half a cup of tomato paste," said Canene-Adams.
Erdman said the study showed that eating whole foods is better
than consuming their components. "It's better to eat tomatoes
than to take a lycopene supplement," he said. "And cooked
tomatoes may be better than raw tomatoes. Chopping and heating
make the cancer-fighting constituents of tomatoes and broccoli
more bioavailable."
"When tomatoes are cooked, for example, the water is removed and
the healthful parts become more concentrated. That doesn't mean
you should stay away from fresh produce. The lesson here, I
think, is to eat a variety of fruits and vegetables prepared in
a variety of ways," Canene-Adams added.
Another recent Erdman study shows that rats fed the tomato
carotenoids phytofluene, lycopene, or a diet containing 10
percent tomato powder for four days had significantly reduced
testosterone levels. "Most prostate cancer is hormone-sensitive,
and reducing testosterone levels may be another way that eating
tomatoes reduces prostate cancer growth," Erdman said.
Erdman said the tomato/broccoli study was a natural to be
carried out at Illinois because of the pioneering work his
colleague Elizabeth Jeffery has done on the cancer-fighting
agents found in broccoli and other cruciferous vegetables.
Jeffery has discovered sulfur compounds in broccoli that enhance
certain enzymes in the human body, which then act to degrade
carcinogens.
"For ten years, I've been learning how the phytochemicals in
tomatoes affect the progression of prostate cancer. Meanwhile
Dr. Jeffery has been investigating the ways in which the
healthful effects of broccoli are produced. Teaming up to see
how these vegetables worked together just made sense and
certainly contributes to our knowledge about dietary treatments
for prostate cancer," said Erdman.
Authors of the tomato/broccoli study are Kirstie Canene-Adams,
Brian L. Lindshield, Elizabeth H. Jeffery, and John W. Erdman
Jr. at the University of Illinois and Shihua Wang and Steven K.
Clinton of The Ohio State University. The study was funded by
the American Institute for Cancer Research and the U.S.
Department of Agriculture.
The U of I study of the effects of tomato carotenoids on serum
testosterone was published in the December 2006 issue of the
Journal of Nutrition. Authors are Jessica K. Campbell, Chad K.
Stroud, Manabu T. Nakamura, Mary Ann Lila, and John W. Erdman
Jr. Funding was provided by the National Institutes of Health's
National Cancer Institute.
Author: Phyllis Picklesimer |