Background: Humulus lupulus(hops) have long been used in beer brewing for their antimicrobial and bittering properties. Hops contain alpha acids, which during the boiling process of beer, get isomerized into iso-alpha-acids also called isohumulones. Research has postulated that daily supplementation with concentrated hop extract could help to reduce visceral obesity in healthy overweight adults. The goal of this systematic review is to summarize recent research on hop extract and its role in reducing visceral obesity.
Methods: An exhaustive search of the available medical literature was performed using MEDLINE-Ovid, Web of Science, CINAHL, and MEDLINE-PubMed. Keywords included hops, hop extract, humulus lupulus, isohumulones, alpha acids, iso-alpha-acids, matured hop bittering acids, alpha-acid axides, mature hop extract, visceral obesity, obesity, and beer. Articles that were relevant were assessed for quality using GRADE.
Results: Six articles were found after an exhaustive search of the literature. Two studies fit the criteria and were used for this systematic review. Both studies were randomized, double blind, placebo-controlled trials. Each study was conducted in an outpatient research setting utilizing matured or isomerized hop extract in the form of capsules or liquid drink. Using computed tomography, both studies successfully showed a reduction in visceral obesity utilizing hop extract on a day-to-day basis. Dose dependent improvement in reduction of visceral obesity was shown in one study.
Conclusion: Utilizing isomerized or matured hop extract on a day-to-day basis can help reduce visceral obesity in overweight healthy adults. The most benefits are seen with dosages greater than 38mg per day of isomerized hop extract and at least 35mg of matured hop extract. Given the ease of creation of hop extract, it should be considered as an adjunctive treatment to diet and exercise for visceral obesity. Further research is still required to determine if results are comparable with larger and more diverse populations and to determine if any risk is involved with supplementation.
Keywords: Hop extract, Humulus lupulus, isohumulones, iso-alpha-acids, beer and visceral obesity
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