Scientists in Taiwan studied the effect of green tea extract on 78
obese women aged 16 to 60 years. They found no significant improvement
in body weight, body mass index and weight circumflex. There were
significant improvements in LDL cholesterol and triglyceride.
Effect of green tea extract on obese women: A randomized, double-blind, placebo-controlled clinical trial.
Clin Nutr. 2008 May 9. [Epub ahead of print]. Hsu CH, Tsai TH, Kao YH, Hwang KC, Tseng TY, Chou P.
AIMS: To examine the effect of green tea extract (GTE) on obese
women and to explore the relationship between GTE and obesity-related
hormone peptides. METHODS: A randomized, double-blind,
placebo-controlled clinical trial was conducted from July 2006 to June
2007 in Taipei Hospital, Taiwan. Seventy-eight of 100 obese women aged
between 16 and 60years with BMI>27kg/m(2) and who had not received
any other weight control maneuvers within the last 3months completed
this study. The subjects were randomly divided into Groups A and B.
Group A (n=41) received GTE while Group B (n=37) took cellulose as a
placebo, one capsule (400mg) three times each day for 12weeks. The body
weight (BW), body mass index (BMI) and waist circumflex (WC) were
measured at the beginning of the study and after 12weeks of treatment
with GTE. The data were compared and expressed as % reduction. RESULTS:
There was only a 0.3% reduction in BW (0.15kg) after 12weeks of
treatment with GTE. There was no statistical difference in % reduction
in BW, BMI and WC between the GTE and placebo groups. Within group
comparison revealed that the GTE group had significant reduction in
LDL-cholesterol and triglyceride, and marked increase in the level of
HDL-cholesterol, adiponectin and ghrelin. On the other hand, the
placebo group showed significant reduction in triglyceride only, and a
marked increase in the level of ghrelin alone. CONCLUSIONS: This study
showed no statistical difference in % reduction in BW, BMI and WC
between the GTE and placebo groups after 12weeks of treatment. The
intake of GTE (491mg catechins containing 302mg EGCG) for 12weeks is
considered safe as shown by the results.
Green tea polyphenols have been reported to preserve tissues such as
blood vessels, corneas, nerves, islet cells, articular cartilage, and
myocardium. Research in Japan examined the effects of EGCG on skin
preservation. Utilizing epidermal and dermal skin cells in culture, the
researchers report that the tea polyphenol helped to preserve the skin
cells for up to seven weeks and allowed successful skin grafting. The
researchers commented that these findings suggest “the future
clinical usefulness of EGCG for skin preservation, however the
mechanism by which EGCG promotes skin preservation still remains
Green tea polyphenols affect skin preservation in rats and improve the rate of skin grafts.
Cell Transplant. 2008;17(1-2):203-9. Kawazoe T, Kim H, Tsuji Y, Morimoto N, Hyon SH, Suzuki S.
Green tea polyphenols have been recently reported to promote the
preservation of tissues, such as blood vessels, corneas, nerves, islet
cells, articular cartilage, and myocardium, at room temperature. These
findings indicate the possibility of a new method of tissue banking
without freezing. A main active ingredient of green tea,
epigallocatechin-3-gallate (EGCG), is a polyphenol that possesses
antioxidant, antimicrobial, antiproliferative, and free radical
scavenging effects. This study examined the effects of EGCG regarding
skin preservation. Skin sample biopsy specimens measuring 1 x 1 cm from
GFP rats were held in sterile containers with 50 ml preserving solution
at 4 degrees C and 37 degrees C for up to about 8 weeks. Periodically,
some of the preserved skin specimens were directly examined
histologically and others were transplanted into nude mice.
Histological examinations of skin preserved at 4 degrees C revealed a
degeneration of the epidermal and dermal layers from 5 weeks in all
groups. In the groups preserved at 37 degrees C, degeneration and
flakiness of the epidermal layer were demonstrated starting at 2 weeks
preservation regardless of addition of EGCG. After 2-7 weeks of
preservation the rat skin grafted to nude mice in the EGCG groups
stored at 4 degrees C showed successful engraftment. However, grafts
preserved at 4 degrees C without EGCG and at 37 degrees C did not
demonstrate GFP-positive keratinocyte or fibroblasts. In conclusion,
the present findings suggest the future clinical usefulness of EGCG for
skin preservation without freezing; however, the mechanism by which
EGCG promotes skin preservation still remains unclear.
New research from Korea shows that EGCG selectively suppressed
keloid fibroblast proliferation and migration compared to its effect on
normal fibroblast proliferation and migration. Keloids are common
benign skin tumors, characterized by collagen accumulation and
hyperproliferation of fibroblasts.
Green Tea Polyphenol Epigallocatechin-3-Gallate Suppresses Collagen
Production and Proliferation in Keloid Fibroblasts via Inhibition of
the STAT3-Signaling Pathway.
J Invest Dermatol. 2008 May 8. Park G, Yoon BS, Moon JH, Kim B, Jun EK, Oh S, Kim H, Song HJ, Noh JY, Oh C, You S.
Keloids are benign skin tumors characterized by collagen
accumulation and hyperproliferation of fibroblasts. To find an
effective therapy for keloids, we explored the pharmacological
potential of (-)-epigallocatechin-3-gallate (EGCG), a widely
investigated tumor-preventive agent. When applied to normal and keloid
fibroblasts (KFs) in vitro, proliferation and migration of KFs were
more strongly suppressed by EGCG than normal fibroblast proliferation
and migration (IC(50): 54.4 muM (keloid fibroblast (KF)) versus 63.0
muM (NF)). The level of Smad2/3, signal transducer and activator of
transcription-3 (STAT3), and p38 phosphorylation is more enhanced in
KFs, and EGCG inhibited phosphorylation of
phosphatidylinositol-3-kinase (PI3K), extracellular signal-regulated
protein kinase 1/2 (ERK1/2), and STAT3 (Tyr705 and Ser727). To evaluate
the contribution of these pathways to keloid pathology, we treated KFs
with specific inhibitors for PI3K, ERK1/2, or STAT3. Although a PI3K
inhibitor significantly suppressed proliferation, PI3K and MEK/ERK
inhibitors had a minor effect on migration and collagen production.
However, a JAK2/STAT3 inhibitor and a STAT3 siRNA strongly suppressed
proliferation, migration, and collagen production by KFs. We also found
that treatment with EGCG suppressed growth and collagen production in
the in vivo keloid model. This study demonstrates that EGCG suppresses
the pathological characteristics of keloids through inhibition of the
STAT3-signaling pathway. We propose that EGCG has potential in the
treatment and prevention of keloids.Journal of Investigative
Dermatology advance online publication, 8 May 2008;