Citrus Peel to Reduce Cholesterol
May 12, 2004
A compound found in the peels of citrus fruit has the
potential to lower cholesterol more effectively than some
prescription drugs, and without side effects, according to a study
by US and Canadian researchers.
A joint study by the US Department of Agriculture and KGK
Synergize, a Canadian nutraceutical company, identified a class of
compounds isolated from orange and tangerine peels and
concentrated in citrus pectin that shows promise in animal studies
as a potent, natural alternative for lowering LDL cholesterol
(so-called 'bad' cholesterol), without the possible side effects,
such as liver disease and muscle weakness, of conventional
cholesterol-lowering drugs.
The findings, released in today's print issue of the Journal of
Agricultural and Food Chemistry, a peer-reviewed publication of
the American Chemical Society, the world's largest scientific
society, show that the compounds, called polymethoxylated flavones
(PMFs), are similar to other plant pigments found in citrus fruits
that have been increasingly linked to health benefits, including
protection against cancer, heart disease and inflammation.
The study is believed to be the first to show that PMFs can
lower cholesterol, the researchers say.
"Our study has shown that PMFs have the most potent
cholesterol-lowering effect of any other citrus flavonoid,"
said Dr Elzbieta Kurowska, lead investigator of the study and vice
president of research at KGK Synergize in Ontario, Canada.
"We believe that PMFs have the potential to rival and even
beat the cholesterol-lowering effect of some prescription drugs,
without the risk of side effects."
PMFs are found in a variety of citrus fruits. The most common
citrus PMFs, tangeretin and nobiletin, are found in the peels of
tangerines and oranges. They are also found in smaller amounts in
the juices of these fruits.
Using hamster models with diet-induced high cholesterol, the
researchers showed that feeding them food containing 1 per cent
PMFs lowered levels of LDL cholesterol by 32 to 40 per cent.
Previous animal studies by others have shown that similar
flavonoids, particularly hesperidin from oranges and naringin from
grapefruit, also may have the ability to lower cholesterol,
although not as effectively as PMFs, according to Kurowska.
Treatment with PMFs did not appear to have any effect on levels
of HDL cholesterol, or good cholesterol, the researcher said. No
negative side effects were seen in the animals that were fed the
compounds, she added.
The researchers are currently exploring the compound's
mechanism of action on cholesterol metabolism. They now suspect,
based on early results in cell and animal studies, that it works
by inhibiting the synthesis of cholesterol and triglycerides
inside the liver.
A long-term human study of the effect of PMFs on high LDL
cholesterol is now in progress. While drinking citrus fruits is
full of health benefits, taking PMF supplements could be an easier
way to lower cholesterol, since a person would have to drink 20 or
more cups a day of orange or tangerine juice to have a therapeutic
effect, Kurowska estimates.
KGK Synergize already has developed a nutrition supplement
containing PMFs combined with a form of vitamin E that seems to
enhance the compound's effect, according to Kurowska. Marketed as
a cholesterol-lowering agent under the trade name Sytrinol, the
supplement recently became available in the US.
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