出口ヨリ子、長田邦子、長南 治、小林邦子、大橋あけみ、橘川俊明、綿貫雅章、大荷満生*、中島久実子*、秦 葭哉*
株式会社 ヤクルト本社中央研究所** （〒186-8650 東京都国立市谷保1796番地）
*杏林大学 老齢医学教室 （〒181-0004 東京都三鷹市新川）
Effectiveness of Consecutive Ingestion and Excess Intake of Guava Leaves Tea in Human Volunteers
Yoriko Deguchi, Kuniko Osada, Osamu Chonan, Kuniko Kobayashi, Akemi Oohashi, Toshiaki Kitsukawa, Masaaki Watanuki, Mitsuo Ooni*, Kumiko Nakajima*, Yoshiya Hata*
Yakult Central Institute for Microbiological Research;
1796 Yaho, Kunitachi-shi, Tokyo 186-8650, Japan
*Department of Medicine and Gerontology, Kyourin University School of Medicine;
*Shinkawa, Mitaka-shi, Tokyo, 181-0004, Japan
Guava tea, which was manufactured from hot water extract of leaves of Psidium guajava L., have been confirmed to inhibit the activities of carbohydrate-degrading enzymes and to suppress the postprandial blood glucose level of human subjects.
In this study, the effect of consecutive ingestion of guava tea on the blood glucose level in human was investigated, by orally administrating to 16 of volunteers whose fasting blood glucose (FBG) were 110mg/dl or higher. One bottle (190ml) of guava tea was given to them at every meal for 12 weeks, during which metabolites of carbohydrate, serum iron, serum lipid and hemological and hemobiological parameters were measured at intervals of 4 weeks to 12 weeks.
After 12 weeks of administration of guava tea, the value of FBG had a tendency toward drop (p=0.07), with a significant reduction rate. The values of FBG in the group (n=7, 111～126mg/dl) which had lower FBG value than the median of initial FBG (137mg/dl) tended to reduce (p=0.06) , compared with those in the group(n=8, 137～186mg/dl) which had higher value than the median of FBG. In addition, the value of HbA1c reduced in 5 of 7 subjects within the former group, while the reduction in the value of HbA1c was observed only in 2 of 8 subjects within the latter group (p=0.07, χ2-test). These results suggested the possibility that blood glucose level could be normally controlled by ingestion of guava tea.
The value of insulin and C-peptide significantly decreased after administration of guava tea.The levels and reduction rate of triglyceride and total cholesterol in subjects whose levels exceeded beyond normal limits significantly after the administration.
Guava tea intake raised no changes in parameters of iron metabolism, liver and kidney functions and of blood chemical data throughout the entire period of the experiment.
To further examine the harmlessness by excess intake of guava tea, the tea in volume of intake three-folds (600ml) of ordinate volume (200ml) was given to 12 healthy adult volunteers. Neither guava tea nor water as control caused diarrhea. Although the slight abdominal symptoms such as gurgling sound and flatulence were observed, these symptoms were not characteristic to guava tea drinking period, because similar symptoms were detected to same extent in water drinking period.In addition, no hypoglycemia was not caused by excess ingestion of guava tea.
The findings stated above indicate that chronic suppression of postprandial blood glucose by administration of guava tea is useful for treatment as an alimentotherapy
(Received November 28,1997)
Key words : グァバ葉 leaves of Psidium guajava L.、空腹時血糖値 fasting blood glucose(FBG)、食後血糖値 postprandial blood glucose、HbA1c、インスリン insulin、胃腸症状 abdominal symptoms、下痢 diarrhea