2004 Fiscal Year Final Research Report Summary
Randomized controlled trial for an effect of green tea consumption on insulin resistance and inflammation markers.
| Project/Area Number |
14570348
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Public health/Health science
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| Research Institution | University of Shizuoka |
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Principal Investigator |
FUKINO Yoko University of Shizuoka, Department of Nutritional Sciences, Associate Professor, 食品栄養科学部, 助教授 (70075000)
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| Co-Investigator(Kenkyū-buntansha) |
AOKI Nobuo Hamamatsu University School of Medicine, Department of Public Health, Professor, 医学部衛生学, 教授 (10109762)
ISO Hiroyasu University of Tsukuba, Department of Public Health Medicine, Professor, 社会医学系, 教授 (50223053)
ISEMURA Mamoru University of Shizuoka, Department of Nutritional Sciences, Professor, 食品栄養科学部, 教授 (40028197)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Green tea consumption / Polyphenol / Fasting blood glucose / Insulin resistance / hs-CRP / Randomized controlled trial / Nutrition intake / Middle age |
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| Research Abstract |
Green tea has been reported to reduce blood glucose levels, but few clinical trial has demonstrated this potential effect. We examined whether green tea-extract powder supplementation improves glucose abnormality. A randomized controlled trial was conducted for volunteers who resided in eastern communities of Shizuoka Prefecture and who had fasting blood glucose levels of ≧6.1 mmol/l or non-fasting blood glucose levels of ≧7.8 mmol/l in a recent health check-up. Sixty subjects aged 32-73 years (49 males and 11 females) participated in the trial. The Early intervention group consumed a packet of green tea-extract powder containing 544 mg polyphenols (456 mg catechins) daily for the first 2 months and then entered the two-month non-intervention period. The Later intervention group was observed for the first 2 months and then consumed green tea-extract powder as described above for the subsequent 2 months. Using the two-period crossover design, we analyzed the changes in fasting hemoglobin A1c level and other biomarkers in blood samples collected at baseline, 2 months and 4 months. A significant reduction in hemoglobin A1c level and a borderline significant reduction in diastolic blood pressure were associated with the intervention. There were no significant changes in weight, body mass index, body fat, systolic blood pressure, fasting serum glucose level, HOMA index, serum lipid level and hypersensitive C-reactive protein level associated with the intervention. Daily supplementary intake of 544 mg green tea polyphenol (456 mg catechins) lowered the hemoglobin A1c level in individuals with borderline diabetes.
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