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Verse kersen goed tegen artritis.*
Arthritis hurts. But fresh
cherries may help.
Results of a preliminary study
by ARS scientists and their university colleagues suggest that some natural
compounds in plump, juicy Bing cherries may reduce painful arthritic
inflammation. Eating cherries may also help lessen the severity of other
inflammatory conditions, such as cardiovascular disease or cancer.
Cherries already have a
reputation for fighting inflammation. So what's new about the ARS study?
"Our test is among the
first to track anti-inflammatory effects of fresh Bing cherries in a controlled
experiment with healthy volunteers," says chemist Robert A. Jacob, who led
the investigation. Jacob is now retired from the ARS Western Human Nutrition
Research Center in Davis, California.
In previous studies at other
laboratories, scientists analyzed extracts from sweet or tart cherries in vitro
to learn more about the fruit's potential health-promoting properties. In
contrast to these test-tube experiments, the California study is apparently the
first to test key inflammatory disease indicators, or markers, in blood samples
from healthy volunteers who were fed precise amounts of fresh Bing cherries.
Reported in a 2003 issue of the Journal of Nutrition, the California
investigation paved the way for a recent followup study at the Davis center.
Life—A Bowl of Cherries?
Imagine being asked to eat a
bowlful of 45 fresh, pitted Bing cherries for breakfast. Ten healthy women, aged
22 to 40, agreed to do that for the California scientists' preliminary study.
Volunteers were instructed not to eat strawberries or other fruits and
vegetables, or to drink tea or red wine, for the 2 days before the cherry
breakfast. These foods are high in antioxidants, thought to fight inflammation.
"They could have interfered with our ability to determine the specific
effects of the Bing cherry antioxidants," explains Jacob.
"Our main focus in this
study was gout, a very painful form of arthritis," says co-investigator
Darshan S. Kelley, a chemist at the nutrition center. "During gout attacks,
crystals of a naturally occurring chemical, uric acid, accumulate in
joints—commonly in the toes—and cause pain. Urate in blood plasma is a
precursor of these uric acid crystals. So, we closely measured volunteers'
levels of plasma urate.
"We also indirectly
measured the amount of urate that was moved out of the body in urine. We took
blood plasma and urine samples before the volunteers ate the cherry breakfast
and at intervals of 1-1/2, 3, and 5 hours afterward."
Volunteers' plasma urate
levels decreased significantly over the 5 hours after their meal of cherries.
Levels of urate removed from the body in urine increased over those 5 hours.
These urate results strongly
suggest that cherries can play an important role in fighting gout. So do the
results from the scientists' assays of some other indicators of inflammation.
Significant changes in the levels of markers are an indication of a healthy
immune system at work, attacking inflammation. Markers monitored included
C-reactive protein, nitric oxide, and tumor necrosis factor alpha.
C-reactive protein, produced
by the liver, increases rapidly during inflammation, such as during a gout
attack. In a healthy body, blood (serum) levels of C-reactive protein are
extremely low.
Another reliable sign of
inflammation: the unwanted increase in nitric oxide. This biochemical is thought
to play a role in damaging arthritic joints. The third marker, tumor necrosis
factor alpha, is secreted in greater quantities when the body is fighting tumors
that may induce inflammation. As is true for C-reactive protein, a healthy body
that isn't fighting an inflammation has very little of this marker.
At the 3-hour monitoring
interval, C-reactive protein and nitric oxide were somewhat lower than at the
start of the study. "Even though these levels were not significantly lower,
the trend was in the right direction and so is of interest," notes Kelley.
Unexpectedly, the scientists
found no change in levels of tumor necrosis factor alpha. That's in contrast to
a previous study, conducted elsewhere, in which natural compounds in fruits and
vegetables were found to decrease levels of this marker. But the trends toward
decreases in the other two markers do agree with results of other scientists'
earlier, in vitro studies of cherry extracts.
Jacob and Kelley collaborated with chemists Giovanna M. Spinozzi and Vicky A. Simon of the nutrition center; chemist Ronald L. Prior, who is with ARS at Little Rock, Arkansas; and research associate Betty Hess-Pierce and professor Adel A. Kader, of the University of California, Davis. (mei 2004)