(Zure)
kersen tegen diabetes en hart- en vaatziekten.*
Uit een studie, met ratten weliswaar, blijkt dat zure kersen de cholesterol-, de triglyceriden-, de suiker- en de insulinewaarden duidelijk doet dalen en dat tevens de lever minder “vet” wordt. In deze studie bleek dat als slechts 1% van de totale dagelijkse voeding uit zure kersen bestaat deze goede waarden al behaald worden. De bioactieve stoffen, anthocyanen blijken voor deze goede resultaten in te staan. Doch uit deze studie blijkt ook duidelijk dat de volledige voeding veel betere resultaten geeft dan de supplementering met alleen de nutriënten zoals in dit geval de anthocyanen. Want uit eerdere studies werden ook goede resultaten behaald met supplementering doch de hoeveelheden die dan ingenomen moesten worden waren voor een mens veel te hoog. Zo snel mogelijk zal nu een studie met mensen worden uitgevoerd.
A
Cherry On Top: Tart Cherries May Alter Heart/Diabetes Factors
Tart cherries may be good for more than
just making pie, according to new data from an animal study conducted by
University of Michigan Health System researchers and presented today at a major
scientific meeting.
In a study involving rats, the researchers report that animals that received
powdered tart cherries in their diet had lower total cholesterol, lower blood
sugar, less fat storage in the liver, lower oxidative stress and increased
production of a molecule that helps the body handle fat and sugar, compared with
rats that didn't receive cherries as part of an otherwise similar diet. All of
the rats had a predisposition toward high cholesterol and pre-diabetes, but not
obesity.
All the measures on which the two groups of animals differed are linked to
metabolic syndrome, a collection of risk factors linked to high rates of heart
disease and Type 2 diabetes. Tens of millions of Americans have metabolic
syndrome; most don't know it.
The researchers say the correlation between cherry intake and significant
changes in metabolic measurements suggest a positive effect from the high
concentrations of antioxidant compounds called anthocyanins that are found in
tart cherries. The new results were given today in an oral presentation at the
Experimental Biology 2007 meeting in Washington, D.C.
It's not yet known if cherry-rich diets might have a similar impact in humans,
but a U-M team will soon launch a small clinical trial to start to find out.
Meanwhile, additional research is being carried out in animals prone to both
obesity and diabetes.
The study's lead author is E. Mitchell Seymour, M.S., a U-M research associate
and supervisor of the U-M Cardioprotection Research Laboratory, which studies
the potential preventive benefits of antioxidant-rich foods. Support for the new
study comes from 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.
Seymour and the laboratory's director, U-M cardiac surgeon Steven Bolling, M.D.,
caution that their results cannot be directly translated into humans. But they
are encouraged by the positive signs seen in the new data.
"Rats fed tart cherries as 1 percent of their total diet had reduced
markers of metabolic syndrome," says Seymour. "Previous research by
other groups studied pure anthocyanin compounds rather than
anthocyanin-containing whole foods, and they used concentrations of anthocyanins
that would be very difficult if not impossible to obtain in the diet."
He continues, "We are interested in a whole-foods approach, using amounts
of fruit that are relevant to human diets. We are enthusiastic about the
findings that tart cherries conferred these beneficial effects at such a modest
daily intake."
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, a professor of cardiac surgery,
co-director of U-M Integrative Medicine and member of the U-M Cardiovascular
Center.
"These data from whole tart cherries join other findings that suggest a
correlation between anthocyanin intake and reductions in cardiovascular and
metabolic risk factors," he says. "But there is still a long way to go
before we can advocate any course of action for humans. Still, the growing body
of knowledge is encouraging."
Bolling and Seymour performed the study using 48 male Dahl Salt-Sensitive rats,
which are bred for their susceptibility to salt-linked high blood pressure, high
cholesterol and impaired glucose tolerance.
For 90 days beginning in their sixth week of life, the rats were fed either a
carbohydrate-enriched diet or a diet that, by weight, included 1 percent
cherries or 10 percent cherries. The higher cherry dose was used to look for any
toxic effects; none were seen.
The cherries were Montmorency tart cherries grown in northern Michigan, frozen,
and powdered. Michigan is the nation's largest producer of tart cherries, which
are used in pies and jams as well as juice. They are different from the sweet
Bing cherries that are often eaten raw, and have higher concentrations of
antioxidant anthocyanins than sweet cherries.
By the end of the study, the rats that received the 1-percent cherry diet had
total cholesterol, triglyceride, glucose and insulin levels that were
significantly lower than those of the rats that did not receive cherries. The
same was true for those on the 10-percent cherry diet, compared with rats that
received a diet with an equivalently high level of carbohydrates not from
cherries.
The researchers also measured plasma TEAC, a measure of antioxidant capacity in
the blood on which a higher reading means better ability to neutralize damaging
free radical molecules produced in the body during metabolism. The rats that
received cherries had higher antioxidant capacity, indicating lower oxidative
stress in their bodies, than those that did not.
In addition to blood measures, the researchers measured the level of fat in the
livers of the rats, and the genetic expression of PPAR (peroxisome
proliferator-activating receptor) in the liver.
The "fatty liver" measure is important because the storage of excess
energy as fat in the liver is a common effect in metabolic syndrome and because
it feeds the vicious cycle of increased cholesterol and decreased response to
insulin that can lead to cardiovascular disease and Type 2 diabetes.
Meanwhile, the measure of PPAR messenger RNA in the liver reflects the readiness
of the liver tissue to express functional PPAR. PPAR is important to the process
by which the body burns fat instead of storing it, and it is important in the
formation of blood lipids like LDL, typically known as the "bad
cholesterol". Drugs in the classes known as thiazolidinediones and
glitazars activate PPAR and are often used to manage high cholesterol and risk
for Type 2 diabetes.
In the current study, the rats that received cherries had both a lower level of
fat in their livers, and a higher expression of the PPAR gene, than those that
did not and the correlation between the two was dose-dependent.
Now, the Cardioprotection Laboratory team has embarked on a new study in rats
that have Type 2 diabetes, both with and without obesity and in the presence of
low-fat and high-fat diets. They will look at whether tart cherries have an
impact on the storage of fat in fat tissue and in muscle, and on the production
of specific blood lipids like LDL and HDL. In addition, they will characterize
cherries chemically, to assess the levels of phytochemicals in whole cherries,
cherry juice and dry cherries.
Meanwhile, U-M Integrative Medicine co-director Sara Warber. M.D., an assistant
professor of family medicine at the U-M Medical School, will lead a pilot
clinical trial of whole tart cherries in humans. The study will enroll healthy
individuals who will spend a night at the U-M General Clinical Research Center,
and have their blood tested multiple times to look for the breakdown products of
cherries.
University of Michigan Health System
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(Juni 2007)