The relationship between the effect of matured hop extract and physical activity on reducing body fat: re-analysis of data from a randomized, double-blind, placebo-controlled parallel group study

Abstract Background We recently reported that successive ingestion of matured hop extract (MHE), produced by oxidation of hops, results in a reduction of body fat in healthy overweight participants. A combined effect of MHE and physical activity on body fat has not been investigated. Thus, we re-analyzed data from the previous study to explore the relationship between the effect of MHE and walking as an index of physical activity. Methods This analysis uses existing data from a randomized, double-blind, placebo-controlled parallel group study in which MHE (active) or placebo was given for 12 w to 200 healthy overweight Japanese, from May to December 2014. Correlation between the change in abdominal fat areas at 12 w and the number of steps taken per day was tested by Spearman’s correlation coefficient test. The subjects were stratified using the average number of steps per day of Japanese into walking less and walking more subgroups (WL and WM, respectively) as follows: placebo (WL, n = 43; WM, n = 44) and active (WL, n = 49; WM, n = 42). Reductions in total, visceral, and subcutaneous fat area (TFA, VFA and SFA, respectively) were evaluated. The interaction effect between ingestion (active/placebo) and walking (WL/WM) was analyzed using two-way analysis of variance (ANOVA). Results There was a significant negative correlation between the change in VFA and daily steps taken in the active group (r = − 0.208, P = 0.048). No significant correlation in TFA or SFA. Although the interaction effect in TFA was not significant, the main effect of ingestion was significant (P = 0.045). In contrast, the interaction effect in VFA was suggested to be synergistic (P = 0.055). Conclusion The results suggested that MHE ingestion combined with light intensity exercise would induce a greater reduction in VFA which would be beneficial for obese or overweight individuals in reducing obesity and obesity-related diseases. Trial registration UMIN-CTR UMIN000014185 registered 6 June 2014

Matured Hop Bittering Components Induce Thermogenesis in Brown Adipose Tissue via Sympathetic Nerve Activity.

Obesity is the principal symptom of metabolic syndrome, which refers to a group of risk factors that increase the likelihood of atherosclerosis. In recent decades there has been a sharp rise in the incidence of obesity throughout the developed world. Iso-α-acids, the bitter compounds derived from hops in beer, have been shown to prevent diet-induced obesity by increasing lipid oxidation in the liver and inhibition of lipid absorption from the intestine. Whereas the sharp bitterness induced by effective dose of iso-α-acids precludes their acceptance as a nutrient, matured hop bittering components (MHB) appear to be more agreeable. Therefore, we tested MHB for an effect on ameliorating diet-induced body fat accumulation in rodents. MHB ingestion had a beneficial effect but, compared to iso-α-acids and despite containing structurally similar compounds, acted via different mechanisms to reduce body fat accumulation. MHB supplementation significantly reduced body weight gain, epididymal white adipose tissue weight, and plasma non-esterified free fatty acid levels in diet-induced obese mice. We also found that uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT) was significantly increased in MHB-fed mice at both the mRNA and protein levels. In addition, MHB administration in rats induced the β-adrenergic signaling cascade, which is related to cAMP accumulation in BAT, suggesting that MHB could modulate sympathetic nerve activity innervating BAT (BAT-SNA). Indeed, single oral administration of MHB elevated BAT-SNA in rats, and this elevation was dissipated by subdiaphragmatic vagotomy. Single oral administration of MHB maintained BAT temperature at a significantly higher level than in control rats. Taken together, these findings indicate that MHB ameliorates diet-induced body fat accumulation, at least partly, by enhancing thermogenesis in BAT via BAT-SNA activation. Our data suggests that MHB is a useful tool for developing functional foods or beverages to counteract the accumulation of body fat

Single oral administration of MHB elevated BAT-SNA in rats.

<p>(A) Time course of BAT-SNA changes taken every 5 min and mean BAT-SNA over 0- to 90- min period. Urethane-anesthetized rats were administered 10 mg/kg of MHB. Data were calculated as a percentage of baseline, and as means ± SEM. n = 3 rats/group. **<i>P</i> < 0.01 (by ANOVA with repeated measures). (B) Effects of 2 mg/kg MHB on mean BAT-SNA over 0- to 90- min period in sham-operated or vagotomized rats. Data are presented as means ± SEM. n = 3 rats/group. **<i>P</i> < 0.01 (by ANOVA with repeated measures).</p

Total food intake of mice fed on HFD with or without MHB supplementation and the effect of MHB on fecal lipid content.

<p>Data are presented as means ± SEM. n = 12 mice/group. No significant differences were observed by unpaired Student’s <i>t</i>-test.</p><p>Total food intake of mice fed on HFD with or without MHB supplementation and the effect of MHB on fecal lipid content.</p

Effect of MHB on plasma components in mice fed on HFD with or without MHB supplementation.

<p>Data are presented as means ± SEM. n = 12 mice/group.</p><p>**<i>P</i> < 0.01 (by unpaired Student’s <i>t</i>-test). NEFA, non-esterified fatty acid.</p><p>Effect of MHB on plasma components in mice fed on HFD with or without MHB supplementation.</p

MHB ameliorated HFD-induced body fat accumulation in mice.

<p>(A) Body weight gain of HFD-fed mice with or without MHB supplementation. Data are presented as means ± SEM. n = 12 mice/group. **<i>P</i> < 0.01 (by analysis of variance (ANOVA) with repeated measures). (B) Epididymal WAT, abdominal subcutaneous WAT and liver weight. Data are presented as means ± SEM. n = 12 mice/group. **<i>P</i> < 0.01 (by unpaired Student’s <i>t</i>-test).</p

Single oral administration of MHB increased the level of cAMP in BAT and elevated its temperature in rats.

<p>(A) cAMP level in the lysates of BAT obtained from rats administered MHB pretreated with propranolol or saline. Thirty minutes after the pretreatment with 10 mg/kg propranolol or saline, rats were administered 10 mg/kg MHB and killed after 3 h. Data are presented as means ± SEM. n = 10 rats/group. **<i>P</i> < 0.01, N.S., not significant (by unpaired Student’s <i>t</i>-test). (B) Time course of BAT temperature changes (ΔT_BAT) taken every 1 min relative to the baseline. The baseline was determined as the mean T_BAT over a 5-min period before the administration of MHB. Urethane-anesthetized rats were administered 10 mg/kg of MHB. Data are presented as means ± SEM. n = 4 rats/group. **<i>P</i> < 0.01 (by ANOVA with repeated measures).</p

Measurement of mRNA expression levels and Immuno-blot analysis in the interscapular BAT of mice fed HFD supplemented with MHB.

<p>(A) mRNA expression levels in BAT. mRNA expression levels were normalized to the expression level of <i>GAPDH</i> as a reference. (B) Immuno-blot analysis of UCP1 in BAT mitochondria. Representative immuno-blots are shown on the histogram. Representative signals shown are from the same immuno-blot membrane. UCP1 protein level was normalized to the level of UQCRC1 protein as a reference. Data are presented as means ± SEM. n = 12 mice/group. *<i>P</i> < 0.05, **<i>P</i> < 0.01 (by unpaired Student’s <i>t</i>-test).</p