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Intake of purple sweet potato beverage affects on serum hepatic biomarker levels of healthy adult men with borderline hepatitis



To examine the effect of purple sweet potato (PSP) beverage rich in acylated anthocyanins on serum hepatic biomarkers in healthy Japanese men.


A randomized, double-blind, placebo-controlled, parallel study.


Kumamoto in Japan.


Healthy adult men (30–60 years) with borderline hepatitis who had one or more of serum γ-glutamyl transferase (GGT), aspertate aminotransferase (AST) and alanine aminotransferase (ALT) levels over normal ranges, and who were negative for hepatitis virus were openly recruited by an advertisement. Of the 48 persons enrolled, 38 (mean age 43.0 years (30–54 years)) completed the study.


The subjects were randomly assigned to the PSP group and the placebo group. During the 8-week intervention, the subjects in the PSP group consumed two bottles of the PSP beverage with acylated anthocyanins (200.3 mg anthocyanins per 125 ml per bottle) per day, and the subjects in the placebo group, two bottles of a placebo beverage (1.7 mg anthocyanins per 125 ml per bottle). All of the data measured were analyzed by two-way repeated measures analysis of variance (ANOVA) with groups and times. The data of the hepatic markers were analyzed using the Dunnett multiple comparison among the time points and t-test between groups at the same time point. Two-sided P<0.05 were defined as the level of significance.


Serum GGT, AST and ALT levels showed interactions (P<0.05) between the beverage groups and time; the others were not affected. The PSP beverage group showed lower hepatic marker levels than the placebo group during the ingestion period, particularly the GGT level (−14.1 IU/l, 95% Confidence intervel (CI) −25.4 to −2.7, P=0.017 at 2 weeks; −16.8 IU/l, 95% CI −36.2 to 2.5, P=0.081 at 4 weeks; −26.7 IU/l, 95% CI −47.6 to −5.7, P=0.014 at 6 weeks and −27.9 IU/l, 95% CI −49.9 to −5.9; P=0.014 at 8 weeks). No correlation between alcohol consumption and each hepatic biomarker level before and after the ingestion was observed.


The intake of the PSP beverage significantly decreased the serum levels of hepatic biomarkers, particularly the GGT level, in healthy men with borderline hepatitis.

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We are grateful to M Watanuki and C Kai of Yakult Honsha for their discussions and advices throughout this study. We also thank Y Suzuki and O Watanabe of the Faculty of Research and Development of Yakult Honsha, for manufacturing the beverage samples and for the adjustment of this study, respectively.

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Correspondence to F Ishikawa.

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Suda, I., Ishikawa, F., Hatakeyama, M. et al. Intake of purple sweet potato beverage affects on serum hepatic biomarker levels of healthy adult men with borderline hepatitis. Eur J Clin Nutr 62, 60–67 (2008).

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  • anthocyanin
  • purple sweet potato
  • γ-glutamyl transferase
  • aspartate aminotransferase
  • alanine aminotransferase
  • hepatitis

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