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Tomato juice keeps
emphysema from developing in new model; Lycopene cited
January 9, 2005 -
American Physiology Society
US FDA last year allowed some tomato
products to carry highly-qualified labeling claims linking tomato products
with reduced incidence of prostate cancer. Research team studies
mechanisms of nutrients in human disease and lifestyle.
Feeding tomato juice to mice kept them from developing
emphysema after cigarette smoke exposure that was long enough to induce
emphysema in a control group, Japanese researchers report in February
issue of the American Journal of Physiology-Lung Cellular and Molecular
Researchers at Juntendo University School of Medicine
first compared the reaction of two mostly similar mouse strains to inhaled
cigarette smoke. Since the lungs of one of the mouse strains "naturally"
age very quickly, the researchers believed that exposure to inhaled
cigarette smoke would induce emphysema in that strain much more quickly
than in the other strain. And indeed, they found that after eight weeks of
breathing 1.5% tobacco smoke through the nose for 30 minutes a day, five
days a week, the test strain, called SAMP1, did develop emphysema, while
the control strain, called SAMR1, did not.
50% tomato juice drink
"completely prevented" smoke-induced emphysema
Then, using the same experimental method, but
substituting a 50% tomato juice mixture for their regular water supply,
the researchers again compared the effect of smoking on the mice. They
found that "smoke-induced emphysema was completely prevented by
concomitant ingestion of lycopene (a potent antioxidant) given as tomato
juice" in SAMP1 mice. They added: "Smoke exposure increased apoptosis and
active caspase-3 of airway and alveolar septal cells and reduced VEGF in
lung tissues, but tomato juice ingestion significantly reduced apoptosis
and increased tissue VEGF level."
The paper, "Tomato juice prevents senescence-accelerated
mouse P1 strain from developing emphysema induced by chronic exposure to
tobacco smoke," appears in the February issue of the American Journal of
Physiology-Lung Cellular and Molecular Physiology, published by the
American Physiological Society. Research was performed by Satoshi Kasagi,
Kuniaki Seyama, Hiroaki Mori, Sanae Souma, Tadashi Sato, Taeko Akiyoshi
and Yoshinosuke Fukuchi at the Juntendo University School of Medicine,
Tokyo, and Hiroyuki Suganuma of the Kagome Research Institute, Tochigi,
FDA questions if effect is from
lycopene alone or tomato juice; Japanese concur
The tomato-lycopene link is made even more interesting
because late last year the U.S. Food and Drug Administration gave
permission for some tomato products to carry highly-qualified labeling
claims linking men's eating tomato products with a reduced incidence of
prostate cancer. In reaching its decision, the FDA noted that it's unclear
whether lycopene alone is responsible for the tomato products' effect.
Similarly, the Japanese researchers noted: "Since mice
were given tomato juice instead of pure lycopene preparation, we can not
exclude the possibility that other ingredients contained in tomato juice
affected the results…."
Model for further study of
pathophysiology and therapeutic intervention
Kuniaki Seyama, coauthor and project leader for the
study, said: "The study demonstrated that the SAMP1 strain is a useful
model for cigarette-smoke induced emphysema and a valuable tool to explore
both pathophysiologic mechanisms and the effect of therapeutic
intervention on smoke-induced emphysema."
Seyama, who is an assistant professor at Juntendo, said
the researchers started out to find a good animal model for studying
smoking, which is a major health problem in Japan as well as globally.
"The basic concept was to establish a mouse model. We looked at the
senescence-accelerated mouse (SAM) because it reaches old age after normal
development and maturation, and we believe that aging itself is an
important component in emphysema."
Lycopene used because it's a
naturally-occurring oxidant in food
Next, the researchers considered "what was the most
important contributing factor in emphysema and we wanted to concentrate on
oxidative stress for two reasons," Seyama said. "First is because the
consequences of oxidative stress during life is considered to be deeply
involved in the aging process. And second, tobacco smoke contains lots of
oxidants and hence puts oxidative stress on the lungs. Using our mouse
model for smoke-induced emphysema, we wanted to intervene in the
accumulation process by changing daily lifestyle, especially eating
habits, "Seyama said. Looking for a natural antioxidant in food, "we
thought lycopene might be a good candidate," he added.
However, Seyama (and the AJP-Lung paper Kasagi et al.)
cautioned: "We can't simply accept that these results go beyond the mouse
model. They are not so smoothly applied to human beings," Seyama noted.
- The team would like to test how tomato juice
ingestion might affect human patients with COPD (chronic obstructive
lung disease), Seyama said.
- Since overall, the researchers are interested in the
mechanisms of nutrients in development of human disease and lifestyle,
this study could lead in several other directions, he added.