Tart Cherries May Become Senior Citizen Favorite –
Lower Risks for Heart Disease, Diabetes
Pain Relief, Too
A participant prepares to eat
cherries in a government study finding the fruit's benefits
fighting inflammation and arthritis pain. See full report below
news story.
Inflammation, body fat, weight gain and blood
cholesterol all lower in rats fed cherries on top of high-fat,
Western-style diet
April 7, 2008 - Tart cherries – frequently sold
dried, frozen or in juice – may have more than just good taste and
bright red color going for them, according to new animal research from
the
University of Michigan Cardiovascular Center.
Rats that received whole tart cherry powder mixed
into a high-fat diet didn’t gain as much weight or build up as much body
fat as rats that didn’t receive cherries. And their blood showed much
lower levels of molecules that indicate the kind of inflammation that
has been linked to heart disease and diabetes. In addition, they had
significantly lower blood levels of
cholesterol and
triglycerides than the other rats.
The results, which were seen in both lean and obese
rats that were bred to have a predisposition to obesity and insulin
resistance, were presented Sunday at the
Experimental Biology 2008 meeting in San Diego, CA by a team from
the
U-M Cardioprotection Research Laboratory.
In addition, the obese rats that received cherry
powder were less likely to build up fat in their bellies – another
factor linked to cardiovascular disease. All the measures on which the
two groups of animals differed are linked to cardiovascular disease and
Type 2 diabetes.
The new findings build on results that were
reported last year at the same meeting by the U-M team. Those data came
from experiments involving lean rats that were prone to high blood
pressure, high cholesterol and impaired glucose tolerance, but that
received a low-fat diet with or without cherries. In that case,
cherry-fed rats had lower total cholesterol, lower blood sugar, less fat
storage in the liver and lower oxidative stress.
Tart cherries are often sold dried,
frozen or in juice form. Courtesy Cherry Marketing Institute,
used with permission.
However, it was unknown if these benefits would be
observed in obesity-prone animals, or in animals fed a higher fat,
western-style diet containing elevated saturated fat and cholesterol.
While it’s still far too early to know whether tart
cherries will have the same effect in humans, U-M researchers are
preparing to launch a pilot-phase clinical trial later this spring. They
note that if a human wanted to eat as many tart cherries as the rats in
the new study did, they would have to consume 1.5 cups every day.
“These new findings are very encouraging,
especially in light of what is becoming known about the interplay
between inflammation, blood lipids, obesity and body composition in
cardiovascular disease and diabetes,” says
Steven Bolling, M.D., a U-M cardiac surgeon and the laboratory’s
director. “The fact that these factors decreased despite the rats’
predisposition to obesity, and despite their high-fat ‘American-style’
diet, is especially interesting.”
The results were presented by E. Mitchell Seymour,
M.S., a U-M research associate and the senior scientist on the project.
“It was recently shown in humans that regular intake of darkly pigmented
fruits like cherries is associated with reduced mortality from
cardiovascular disease and coronary heart disease,” says Seymour.
“The heart-health benefits of these colorful fruits
were sustained even when corrected for age and other health conditions.
We’re now invested in exploring the specific mechanisms of these
benefits.”
The experiments are funded by an unrestricted grant
from the
Cherry Marketing Institute, a trade association for the cherry
industry. CMI has no influence on the design, conduct or analysis of any
U-M research it funds.
The correlation between cherry intake and
significant changes in cardiovascular risk factors suggests — but does
not directly demonstrate — a positive effect from the high
concentrations of antioxidant compounds called anthocyanins that are
found in tart cherries. The anthocyanins are responsible for the color
of these and of other darkly pigmented fruits.
The potential for protective effects from
antioxidant-rich foods and food extracts is a promising area of
research, says Bolling, who is the Gayle Halperin Kahn Professor of
Integrative Medicine at U-M.
The team performed the study using 48 obesity-prone
rats, half of which were obese, and a diet in which 45 percent of
calories came from fat and 35 percent came from carbohydrates. All the
rats were six weeks old when study began. For the next 90 days they were
fed either a cherry-enriched diet in which cherries made up 1 percent by
weight, or a diet that contained an equivalent number of carbohydrates
and calories.
At the end of the study, the rats had blood tests
for glucose, cholesterol and triglyceride levels, received DEXA scans to
measure their body fat and to see where the fat had collected, and had
tests for two plasma inflammation markers: TNF-alpha and interleukin-6.
These two molecules are related to the level of
vascular inflammation, or immune-system reaction to blood-vessel walls,
that is often seen in people and animals with cardiovascular disease.
While inflammation is a normal process the body uses to fight off
infection or injury, according to recent science, a chronic state of
inflammation may increase the risk for a number of diseases.
The cherries were Montmorency tart cherries grown
in Michigan, which is the nation’s largest producer of tart cherries.
They are different from the sweet Bing cherries that are often eaten
fresh. Tart cherries have higher concentrations of antioxidant
anthocyanins than sweet cherries.
By the end of the study, the rats that received the
cherries had lower body weight, fat mass, total cholesterol,
triglyceride, TNF-alpha and IL-6 than the rats that did not receive
cherries. In all, TNF-alpha was reduced by 50 percent in the lean rats
and 40 percent in the obese rats and IL-6 was lowered by 31 percent in
the obese rats and 38 percent in the lean rats.
The obese rats that received cherries also had
lower-weight retroperitoneal fat, a type of belly fat that has been
associated with especially high cardiovascular risk and inflammation in
humans.
In addition to Seymour and Bolling, the research
team includes Daniel Urcuyo-Llanes, Ara Kirakosyan, Peter B. Kaufman,
and Sarah K. Lewis of U-M, and Maurice Bennink of Michigan State
University.
Even as the Cardioprotection Laboratory team
continues its work in animals,
U-M Integrative Medicine co-director
Sara Warber, M.D., an assistant professor of family medicine at the
U-M Medical School, is preparing to lead a pilot clinical trial of whole
tart cherries in humans.
For more information on the University of Michigan
Cardioprotection Laboratory, visit
http://sitemaker.umich.edu/cardiac.phytomed. For information on
participating in clinical trials at U-M, visit
www.umengage.org. Reference: Experimental Biology 2008 poster #702.7
Report from 2004 Agriculture Research magazine
explains pain relief from cheeries, sees possible help in fighting
cardiovascular disease, cancer
May,
2004 - Results of a preliminary study by Agriculture Research Service of
the USDA (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.
A Month of Fresh Cherries
The follow-up study, conducted in 2003, involved
more people, more cherries, and a greater array of inflammatory-response
markers. Eighteen women and two men—aged 22 to 40—participated in the
64-day investigation.
Many of the new volunteers began the study with
elevated C-reactive protein levels. "That made it easier to detect any
decline in C-reactive protein levels as the study progressed," says
Kelley. "We're particularly interested in this protein because a recent
major study indicated that it's more reliable than cholesterol as a
predictor of cardiovascular disease.
"This group ate the same daily amount of fresh Bing
cherries as our earlier volunteers. But we asked them to eat the
cherries throughout the day instead of just at breakfast." The
volunteers did that for 28 consecutive days. The researchers are now
analyzing blood samples.
The grower-sponsored California Cherry Advisory
Board helped fund the research. Final results should be available later
this year. Then we'll know more about the health benefits of this sweet
treat.—By
Marcia Wood, Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS
National Program (#107) described on the World Wide Web at
www.nps.ars.usda.gov.
