Citrus Peel
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.
