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An article published in the February, 2009 Journal of Nutrition
reported the outcome of a clinical trial which found a lowering effect
for green tea catechins on abdominal fat and triglycerides in
overweight adults. Increased abdominal fat is a factor associated with
metabolic syndrome, which increases the risk of diabetes and heart
disease.
Kevin
C. Maki of Provident Clinical Research in Bloomington, Indiana, along
with coauthors including Jeffrey B. Blumberg of Tufts University in
Boston, randomized 132 overweight or obese adults to receive a beverage
containing approximately 625 milligrams green tea catechins (including
gallocatechin, epigallocatechin, catechin, epicatechin, EGCG,
gallocatechin gallate, epicatechin gallate and catechin gallate) and 39
milligrams caffeine, or a beverage containing the same amount of
caffeine without catechins daily for twelve weeks. Participants were
requested to maintain the same amount of caloric intake and to engage
in at least 180 minutes per week of exercise, including at least three
supervised sessions each week. Body composition, serum lipids, and
other factors were assessed at the beginning and end of the study.
Both
groups lost weight by the end of the study, yet participants who
received catechins experienced a greater amount of weight loss than
those who consumed the control beverage. When fat mass was considered,
the percentage lost was greater in the catechin group, although the
amount was not considered significant. However, total abdominal fat
area, subcutaneous abdominal fat and serum triglycerides were
significantly lower in subjects who received green tea catechins.
Tea
catechins’ most commonly studied mechanisms of action on body
composition are that of improving thermogenesis and increased fat
oxidation. “Our results are not inconsistent with the possibility that
catechin consumption increases energy expenditure to a degree that
could produce clinically important changes in body fat over time,” the
authors write. “Larger and/or longer trials will be needed to test this
hypothesis.
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