Efficacy of tea catechin-rich beverages to reduce abdominal adiposity and metabolic syndrome risks in obese and overweight subjects: a pooled analysis of 6 human trials.

This post hoc pooled analysis assessed the effectiveness of green tea catechins (GTC) to reduce the risk of metabolic syndrome (MetS) associated with abdominal fat reduction, because previous findings are unclear. Data were pooled from six human trials (n=921, 505 men) comparing the effects of GTC-containing beverages (540-588 mg GTC/beverage) and a placebo beverage. Outcome measures were abdominal fat [total fat area (TFA), visceral fat area (VFA), subcutaneous fat area (SFA)], and MetS risk. We estimated mean changes from baseline and calculated confidence intervals (CI) to assess reductions in abdominal fat accumulation and MetS improvement. Subclass analyses were performed by classifying subjects as Pre-MetS or MetS at trial initiation. Additional subclass analyses were performed with Pre-MetS and MetS subjects further stratified according to whether GTC intake reduced TFA, VFA, or SFA. Consumption of GTC-containing beverages for 12 weeks significantly reduced TFA (-17.7cm2, 95%CI: -20.9 to -14.4), VFA (-7.5cm2, 95%CI: -9.3 to -5.7), SFA (-10.2cm2, 95%CI: -12.5 to -7.8), body weight, body mass index, and waist circumference; and improved blood pressure. Subclass analyses of Pre-MetS and MetS subjects showed improved MetS in the GTC group [odds ratio (OR), 1.67; 95%CI: 1.08-2.57]. The ORs for improved MetS in the TFA- and VFA-reduced groups were 2.79 (95%CI: 1.28-6.09) and 4.36 (95%CI: 2.03-9.39), respectively. Continual consumption of GTC-containing beverages reduced abdominal fat and improved MetS, suggesting its potential to prevent diabetes and cardiovascular disease. Additional large-scale intervention trials are needed to evaluate the effects of GTC on the risk of MetS in high-risk populations.

Minor effects of green tea catechin supplementation on cardiovascular risk markers in active older people: a randomized controlled trial.

AIM: Although previous studies have shown that consumption of green tea catechins (GTC) and walking might prevent development of cardiovascular disease (CVD), the effects of GTC supplementation on CVD risk in active older people are unknown. METHODS: A total of 52 older adults (male/female 20/32, mean age 69.1 ± 5.9 years) participating in a pedometer-based walking program were randomly assigned to a GTC group with an intake of 630.9 mg GTC daily (n=26) or a control group (n=26) for 14 weeks. Cardiovascular risk markers were measured before and after this trial. RESULTS: In the GTC group, values of the following markers were significantly reduced (P<0.05) from the beginning to the end of the trial: waist circumference (from 84.2 ± 8.4 to 82.2 ± 8.5 cm), hip circumference (from 95.1 ± 6.9 to 92.2 ± 6.3 cm), total cholesterol (from 233.0 ± 46.3 to 218.8 ± 42.3 mg/dL), low-density lipoprotein cholesterol (from 130.4 ± 36.2 to 119.1 ± 33.4 mg/dL) and low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (from 2.0 ± 1.7 to 1.7 ± 0.5); only hip circumference (from 95.6 ± 8.1 to 94.1 ± 7.6 cm) was significantly reduced (P<0.05) in the control group. No significant between-group differences were found for any parameter measured. CONCLUSIONS: Although GTC might reduce cholesterol levels, the present randomized control trial suggests that GTC supplementation in active older participants did not significantly affect cardiovascular risk markers. Future studies should identify more effective combinations of GTC supplementation and physical activity.

Effectiveness and safety of 1-year ad libitum consumption of a high-catechin beverage under nutritional guidance.

BACKGROUND: It has been reported that a continuous intake of a catechin beverage will reduce body fat. Traditionally, improvement of eating and exercise habits has been the basis for prevention and reduction of obesity. In this study, we conducted a trial involving human subjects who ingested a catechin beverage for 1 year under nutritional guidance. METHODS: This study was conducted based on a comprehensive cohort design using a catechin beverage (containing 588 mg of tea catechins) and a control beverage (containing 126 mg of tea catechins). At both the start and the end of the trial, the subjects underwent an annual health check and computer tomography for measurement of their abdominal fat. In addition, a food intake survey was conducted and all subjects were provided nutritional guidance by a registered dietitian every 3 months. RESULTS: Data were analyzed using per protocol samples of 134 subjects (catechin group, n = 77; control group, n = 57). Body weight and body mass index were reduced significantly in the catechin group compared to the control group. Changes in body weight during the study period were -1.1 kg in the catechin group and 0.2 kg in the control group. In the catechin group, the visceral fat areas at the start of the trial were significantly correlated with the magnitude of fat reduction at the end of the trial. Under the guidance of a registered dietitian, subjects in the catechin group who showed a reduction in their fat-derived energy percentage during the test period tended to reduce more body weight than those with an increase in this percentage, although no difference in total energy intake was noted between the two groups. One-year ad libitum consumption of a catechin beverage posed no health risks and resulted in a reduction in body weight. CONCLUSIONS: An overall improvement in dietary habits might enhance the weight-reduction effect of the beverage.

Effect of diacylglycerol on postprandial lipid metabolism in non-diabetic subjects with and without insulin resistance.

The effects of diacylglycerol ingestion on postprandial lipid metabolism in non-diabetic subjects with and without insulin resistance were investigated. This was single dose ingestion study, in a double blind cross over manner and postprandial lipid concentrations were compared between diacylglycerol oil (DAG) and triacylglycerol oil (TAG) ingestion. The subjects were 18 male volunteers and homeostasis model assessment (HOMA-R) was used to classify them into insulin sensitive (IS, n=10, HOMA-R<2.0) and insulin resistant (IR, n=8, HOMA-R> or =2.0) groups. Fasting serum triglycerides (TG) and remnant-like particle cholesterol (RLP-C) correlated with HOMA-R and were significantly higher in the IR as compared to the IS group. Postprandial increments of TG and RLP-C after DAG ingestion were significantly lower as compared to those after TAG ingestion. In a case of TAG ingestion, their increments positively correlated with HOMA-R and were significantly higher in the IR as compared with the IS group. In contrast, their increments remained constant after DAG ingestion in both groups. In the IR group, the postprandial lipidemia were reduced after DAG ingestion to about half of those after TAG ingestion. In conclusion, DAG reduced postprandial lipidemia especially in subjects with insulin resistance and may be beneficial in preventing atherosclerosis and related diseases.