Prevention of diet-induced obesity by dietary isomerized hop extract containing isohumulones, in rodents

• Published in: International Journal of Obesity Vol. 29; no. 8; pp. 991 - 997
• Main Authors: YAJIMA, H, NOGUCHI, T, IKESHIMA, E, SHIRAKI, M, KANAYA, T, TSUBOYAMA-KASAOKA, N, EZAKI, O, OIKAWA, S, KONDO, K
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 01.08.2005; Nature Publishing Group
• Subjects: Absorption; Animals; Base Sequence; Beer; Biological and medical sciences; Biosynthesis; Body weight; Breweries; Cardiovascular disease; Cyclopentanes - therapeutic use; Diet; Dietary Supplements; Diseases of the digestive system; Emulsions; Excretion; Fatty acids; Feces - chemistry; Gene Expression; Glucose; Glucose Tolerance Test; Hyperlipidemia; Insulin; Insulin Resistance; Laboratories; Lipase - analysis; Lipid Metabolism; Lipids; Lipids - analysis; Liver - metabolism; Medical sciences; Metabolic diseases; Metabolic disorders; Metabolism; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Molecular Sequence Data; Nutrition; Obesity; Obesity - metabolism; Obesity - prevention & control; Oral administration; Oxidation; Phytotherapy; Plasma; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Species Specificity; Triglycerides - biosynthesis; Triglycerides - blood; Japan; Obesity; isohumulones; isomerized hop extract; Nutrition disorder; Rodentia; Extract; diet-induced obesity; Feeding; Prevention; Vertebrata; Mammalia; Diet therapy; Diet; hops; Nutritional status
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/sj.ijo.0802965

Isomerized hop extract (IHE), which consists mainly of isohumulones and is required in the beer brewing process, was investigated for its effects on diet-induced obesity in two strains of mice. C57BL/6N and KK-A(y) mice were fed a standard or high-fat diet containing IHE and their body and tissue weights were measured at various time points. Oral glucose tolerance tests (OGTT) and insulin tolerance tests (ITT) were carried out in high-fat diet-fed C57BL/6N mice. The effects of IHE on intestinal lipid absorption were examined in Wistar rats using a plasma triacylglycerol assay after oral administration of a lipid emulsion. Fecal lipid levels were also measured in these animals after they were fed a high-fat diet containing IHE for 15 days. The effects of IHE on pancreatic lipase activity and the expression of genes involved in hepatic lipid metabolism were also examined using an in vitro assay and quantitative RT-PCR, respectively. Supplementation of high-fat-containing chow with IHE reduced body weight gain and improved glucose tolerance in our experimental mice. A reduction in body weight gain was also observed in C57BL/6N mice fed a standard diet containing IHE. Wistar rats fed a high-fat diet containing IHE showed reduced plasma triacylglycerol levels and an increase in their fecal lipid excretion. Similarly, their pancreatic lipase activity was inhibited and their elevation in plasma triacylglycerol levels seen after the oral administration of lipid emulsion was significantly suppressed. IHE-fed mice showed an increased expression in their lipid oxidation genes and a decreased expression in genes involved in triacylglycerol biosynthesis. The inhibition of intestinal dietary fat absorption may be the mechanism by which IHE induces its weight-lowering effects in high-fat diet-fed mice. The modulatory effect of IHE on lipid metabolism may also, at least partly, be responsible for its beneficial effects on body weight gain. These results suggest that IHE may be helpful in humans in preventing diet-induced obesity and perhaps even metabolic syndrome, the latter of which is known to be associated with obesity.