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| Date: 11-30-2016 | HC# 051666-557 |
Morimoto-Kobayashi Y, Ohara K, Ashigai H, et al. Matured hop extract reduces body fat in healthy overweight humans: a randomized, double-blind, placebo-controlled parallel group study. Nutr J. March 9, 2016;15:25. doi: 10.1186/s12937-016-0144-2.
Obesity, on the rise worldwide, is associated with elevated risk of metabolic disease such as diabetes and cardiovascular disease. Dietary changes are recommended, along with other lifestyle modifications, in addressing this condition. As part of this strategy, functional foods with certain bioactive properties may help. Hops (Humulus lupulus, Cannabaceae) is traditionally used in the brewing process, and its bitter taste comes from several compounds. Bioactive matured hop bitter acids (MHBAs), known to increase during storage, have been shown to decrease body fat in an animal model. This randomized, double-blind, placebo-controlled, parallel-group trial investigated the impact of mature hops extract (MHE, standardized to 18.3% MHBAs) on body fat in healthy, overweight subjects.
This trial was registered with the University hospital Medical Information Network (UMIN) Clinical Trials Registry in Japan as UMIN000014185 and conducted by TTC Co., Ltd. (Tokyo, Japan), a contract research organization, from May 2014 to December 2014. Included subjects had a body mass index (BMI) of ≥ 25 and < 30 kg/m2. The exclusion criteria were dieting, treating body fat or lipid metabolism with pharmaceuticals or dietary supplements, consuming hops or excessive alcohol, allergic reactions, other systemic diseases, pregnancy or lactation, abnormal blood results, participation in another clinical trial within a month, and blood donation.
Hops pellets of 300 g were procured from Hopsteiner GmbH; Mainburg, Germany. The pellets were kept at 60°C for 2 hours, and then extracted with water at 50°C for 1 hour. After several filtration steps, resultant liquid comprised the MHE and was standardized to 18.3% MHBAs. The material in the trial consisted of 350 ml of MHE test beverage (containing 35 mg of MHBAs) or placebo. The content of placebo is not described, but it is mentioned that it matched the MHE preparation in taste and appearance. The energy (kcal), carbohydrate, and fiber contents of the MHE beverage and placebo also were matched.
The study duration was 18 weeks, with a 2-week screening period, 12 weeks of MHE drink or placebo consumption, and 4 weeks of follow up. Study visits occurred at baseline, 4, 8, and 12 weeks of treatment, and at 16 weeks (4 weeks after finishing treatment). During screening, subjects completed a lifestyle questionnaire and were randomly assigned to either the treatment or placebo group. Ingestion of test material occurred once per day; at study visits, the test drink was consumed after physical parameters were measured. Subjects were encouraged to maintain their lifestyle, but were instructed to avoid alcohol the day before study visits and fast beginning at 10 p.m. the night before clinical visits.
Body weight, body fat ratio, waist and hip circumference, systolic and diastolic blood pressure, and pulse rate were measured at each visit. Abdominal fat area was measured with a computerized tomography (CT) scan at baseline, 8, 12, and 16 weeks. Blood and urine parameters were assessed, and subjects kept a diary of food, steps, and other physical activity. The primary endpoint was any decrease of abdominal fat area, with secondary endpoints being any changes in physical parameters. Adverse side effects were reported by subjects, and laboratory parameters served as safety indications.
From a total of 511 subjects screened, 200 were randomly assigned (100 men and 100 women) to either the treatment or placebo group. Baseline parameters were not significantly different between groups. There was a significant decrease in energy intake in the treatment group at the 16-week time point as compared to baseline (1728.5 ± 46.3 vs. 1810.1 ± 50.9 kcal/day; P<0.05) but not different than placebo at week 16 (1769.7 ± 45.7). Fiber intake also decreased in this group after 4 weeks of treatment consumption as compared to baseline (9.98 ± 0.34 g/day vs. 10.79 ± 0.47 g/day; P<0.05). In both groups, visceral and total fat areas significantly decreased from baseline to 12 weeks of the study (P<0.01 for both). Additionally, both visceral and total fat areas were significantly lower than those of the placebo group after 12 weeks in the study (P<0.05 for both). Subcutaneous fat areas also were significantly decreased in both groups after 12 weeks (P<0.01 for both) but were not significantly different between groups at any time point.
Following 4, 8, and 12 weeks of treatment, the body fat ratio in those in the treatment group was significantly less as compared to the placebo group (P<0.05 for all). Also, both body weight and BMI were significantly lower in the treatment group as compared with the placebo group after 4 weeks of the study (P<0.01 for both). In the group consuming the MHE beverage, body weight and BMI were significantly decreased after 16 weeks as compared to baseline (P<0.01), with no significant change in the placebo group. Both waist and hip circumference were significantly smaller in the treatment group at the 4-week time point as compared to placebo (P<0.05 for both).
In the placebo group, systolic blood pressure was significantly higher after 16 weeks of the study as compared to baseline (P<0.05). Also, pulse rate was significantly slower in the treatment group as compared to the placebo group after 16 weeks (P<0.05). Adverse side effects were reported by 47 subjects in the treatment group and 43 subjects in the placebo group, with the most common one being cold-like symptoms. None of the effects were determined to be associated with the test material.
This study demonstrated that the consumption of MHE decreased fat accumulation in subjects with a BMI between 25 and 30. Also, energy intake was significantly decreased in those taking MHE, further implying that appetite suppression may be involved. This is discussed as a mechanism that may be linked to bitterness, as other bitter compounds have also impacted appetite and satiety by acting on the gastrointestinal tract. It is suggested that future studies should incorporate a longer duration. This study had significant placebo effects, warranting rigorous further trials. Also, the energy intake of the study subjects in Japan was low compared to average energy intake in Western societies. Despite this, MHBA compounds may be a useful resource to lose weight.
This study was sponsored by Kirin Company, Ltd (Yokohama, Japan), a brewery, and 9 of the authors are employees of the company.
—Amy C. Keller, PhD
