Original Article

European Journal of Clinical Nutrition (2008) 62, 60–67; doi:10.1038/sj.ejcn.1602674; published online 14 February 2007

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

I Suda1, F Ishikawa2, M Hatakeyama3, M Miyawaki4, T Kudo5, K Hirano5, A Ito5, O Yamakawa1 and S Horiuchi6

  1. 1National Agricultural Research Center for Kyushu Okinawa Region, Kumamoto, Japan
  2. 2Yakult Central Institute for Microbiological Research, Tokyo, Japan
  3. 3SAKURA Inc., Kumamoto, Japan
  4. 4Miyawaki Clinic, Kumamoto, Japan
  5. 5Faculty of Research and Development, Yakult Honsha, Tokyo, Japan
  6. 6Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan

Correspondence: Dr F Ishikawa, Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo, 186-8650, Japan. E-mail: fumiyasu-ishikawa@yakult.co.jp

Received 9 August 2006; Revised 12 December 2006; Accepted 18 December 2006; Published online 14 February 2007.

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Abstract

Objective:

 

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

Design:

 

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

Setting:

 

Kumamoto in Japan.

Subjects:

 

Healthy adult men (30–60 years) with borderline hepatitis who had one or more of serum italic gamma-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.

Methods:

 

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.

Results:

 

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.

Conclusion:

 

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

Keywords:

anthocyanin, purple sweet potato, italic gamma-glutamyl transferase, aspartate aminotransferase, alanine aminotransferase, hepatitis

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