Matured hop extract reduces body fat in healthy overweight humans: a randomized, double-blind, placebo-controlled parallel group study.

Yumie Morimoto-Kobayashi,Mikio Katayama,Sumio Kondo,Tomoka Kanaya,Kumiko Koizumi,Hiroshi Ashigai,Yasuyuki Kowatari,Fumitoshi Manabe,Kazuaki Ohara,Yoshimasa Taniguchi,Yuji Kaneko

doi:10.1186/s12937-016-0144-2

Abstract

BackgroundHops are the main components of beer that provide flavor and bitterness. Iso-α-acids, the bitter components of beer, have been reported to reduce body fat in humans, but the bitterness induced by effective doses of iso-α-acids precludes their acceptance as a nutrient. The matured hop bitter acids (MHBA) of oxidized hops appear to have a more pleasant bitterness compared to the sharper bitterness of iso-α-acids. While there has been little information concerning the identity of the MHBA compounds and their physiological effects, MHBA was recently found to be primarily composed of oxides derived from α-acids, and structurally similar to iso-α-acids. Here, we investigated the effects of matured hop extract (MHE) containing MHBA on reducing abdominal body fat in healthy subjects with a body mass index (BMI) of 25 to below 30 kg/m2, classified as “obese level 1” in Japan or as “overweight” by the WHO.Trial designA randomized, double-blind, placebo-controlled parallel group study.MethodsTwo hundred subjects (male and female aged 20 to below 65 years with a BMI of 25 or more and less than 30 kg/m2) were randomly assigned to two groups. During a 12-week ingestion period, the subjects in each group ingested daily 350 mL of test-beverage, either containing MHE (with 35 mg MHBA), i.e. the namely active beverage, or a placebo beverage without MHE. The primary endpoint was reduction of the abdominal fat area as determined by CT scanning after continual ingestion of MHE for 12 weeks.ResultsCompared to the placebo group, a significant reduction was observed in the visceral fat area after 8 and 12 w, and in the total fat area after 12 w in the active group. There was also a concomitant decrease in body fat ratio in the active group compared to the placebo group. No adverse events related to the test beverages or clinically relevant abnormal changes in the circulatory, blood and urine parameters were observed in either group.ConclusionsThe present study suggests that continual ingestion of MHE safely reduces body fat, particularly the abdominal visceral fat of healthy overweight subjects.Trial registrationUMIN-CTR UMIN000014185 Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-016-0144-2) contains supplementary material, which is available to authorized users.

Highlights

Obesity increases the risk of metabolic disorders, such as insulin resistance, hyperlipidemia and hypertension, which are risk factors of cardiovascular disease [1,2,3]
There was a concomitant decrease in body fat ratio in the active group compared to the placebo group
The present study suggests that continual ingestion of matured hop extract (MHE) safely reduces body fat, the abdominal visceral fat of healthy overweight subjects

Summary

Introduction

Obesity increases the risk of metabolic disorders, such as insulin resistance, hyperlipidemia and hypertension, which are risk factors of cardiovascular disease [1,2,3]. It has been found that these components, called matured hop bitter acids (MHBA), primarily consist of α-acid oxides, which possess a common β-tricarbonyl moiety in their structures similar to α-, β- and iso-α-acids [13,14,15,16]. A recent study suggested that the oxidation products of α-acids may result in a more pleasant tasting bitterness compared to the sharper bitterness of iso-α-acids [17]. Iso-α-acids, the bitter components of beer, have been reported to reduce body fat in humans, but the bitterness induced by effective doses of iso-α-acids precludes their acceptance as a nutrient. While there has been little information concerning the identity of the MHBA compounds and their physiological effects, MHBA was recently found to be primarily composed of oxides derived from α-acids, and structurally similar to iso-α-acids. We investigated the effects of matured hop extract (MHE) containing MHBA on reducing abdominal body fat in healthy subjects with a body mass index (BMI) of 25 to below 30 kg/m2, classified as “obese level 1” in Japan or as “overweight” by the WHO.

Methods

Results

Discussion

Conclusion