Randomized trial of amino acid mixture combined with physical activity promotion for abdominal fat reduction in overweight adults

Abstract

Purpose

The purpose of this study was to test the efficacy of arginine, alanine, and phenylalanine mixture (A-mix) ingestion at 1,500 mg/day in combination with the promotion of physical activity for abdominal fat reduction in overweight adults.

Methods

A placebo-controlled, double-blind, parallel-group, randomized trial for 12 weeks combined with a 4-week follow-up period was conducted at a single center in Minato-ku, Tokyo, Japan, between December 2016 and May 2017. Data were analyzed between June and August 2017. The study participants were 200 overweight adults within the age range of 20–64 years. The participants were randomly assigned to the A-mix group (n=100) or a placebo group (n=100) and were administered 500 mL of test beverage containing 1,500 or 0 mg of A-mix, respectively, for 12 weeks. All participants maintained a physically active lifestyle between week 0 and week 12 through monthly sessions of physical activity. The primary outcomes were the 12-week changes in the abdominal total, subcutaneous, and visceral fat areas, as assessed by computed tomography.

Results

Of the 200 enrolled participants, 199 (99%) accomplished the 12-week intervention and 4-week follow-up period. The per-protocol-based analysis for 194 participants demonstrated that the abdominal total fat area decreased significantly in the A-mix group compared with that in the placebo group (difference, 10.0 cm²; 95% confidence interval [CI]: 0.4–19.6 cm²; P=0.041). Comparable outcomes were obtained for the abdominal subcutaneous fat area (difference, 7.4 cm²; 95% CI: 0.1–14.7 cm²; P=0.047). No study-related unfavorable events occurred.

Conclusion

A-mix supplementation in combination with physical activity promotion facilitated abdominal fat reduction in overweight adults.

Keywords:

• amino acid supplementation
• physical activity promotion
• abdominal fat
• randomized controlled trial

Acknowledgments

This trial was based on a collaborative research agreement between the University of Tsukuba Faculty of Medicine and Meiji Co., Ltd. Mr Takuya Nagai, Ms Fuyuko Yamamoto, and Mr Akio Tanaka produced and provided the test beverages used in this trial. Dr Naotaka Hashizume generated the randomization codes and created an allocation table. Ms Yuriko Sakairi provided administrative support and encouragement throughout the study. Data acquisition performed by staff from KSO Corporation. We gratefully acknowledge the contributions of all trial staff. Editorial support in the form of medical writing was provided by Editage.

Author contributions

Study concept and design: KU, HS, CS, SI, and YN. Intervention: TT and YN. Statistical analysis: NS. Study physician: SS. Safety committee: HK. Interpretation: KU, HS, SS, and YN. Writing the first draft: KU. Overall supervision as a principal investigator: YN. All authors contributed toward revising the paper and agree to be accountable for all aspects of the work.

Disclosure

KU, CS, and SI are employees of Meiji Co., Ltd. The other authors HS, TT, HK, NS, SS, and YN report no conflicts of interest in this work.