Osteoporosis is a bone condition characterized by weakened and brittle bones, leading to an increased risk of fractures. Oestrogens play a vital role in maintaining bone health, whereby oestrogen deficiency elevates the risk of osteoporosis and fractures, particularly in menopausal women due to the decline in oestrogen levels. Phytoestrogens, plant-derived compounds capable of interacting with human oestrogen receptors, have presented an intriguing non-pharmaceutical avenue for preventing bone loss. Other phytoestrogens have received some attention in the field, however, limited human research exists on prenylflavonoids, a phytoestrogens found in hops (Humulus lupulus). This randomized, double-blinded, placebo-controlled trial aimed to investigate the effects of a year-long supplementation of standardised hop extract (8-PN) Lifenol® on bone mineral density in postmenopausal women. Additionally, the study explored potential mechanisms, particularly focusing on changes in gut bacteria. Notably, gut bacteria play a role in bone metabolism and the pathogenesis of osteoporosis. They are also, along with the liver, responsible for converting hops phenols into active phytoestrogenic compounds. The trial was completed by 95 postmenopausal, women with Osteopenia aged 50 to 85. They all received calcium and vitamin D3 tablets in addition either a hop extract (100mcg) or a placebo for 48 weeks. Changes were monitored using DXA scans for bone mineral density (BMD) and bone metabolism, blood samples for markers for bone health, a quality of life questionnaire, gut microbiome testing, and tests for short-chain fatty acid (SCFA) levels. In conclusion, the intake of hop extract confirmed a previously observed trend of a slight increase in total bone mineral density (BMD), in addition to the benefits linked to calcium and vitamin D supplementation. Although there were no significant changes in the composition of gut bacteria and SCFA levels, the hop extract candidates had a higher abundance of specific genera associated with total body BMD, suggesting a potential positive impact. Larger studies are required to validate these findings.