Associations between dietary flavonoid intakes and bone health in a Scottish population

Flavonoids are bioactive polyphenols found particularly in fruit and vegetables, but little is known about their role in bone health in humans. The aim of this observational study was to investigate whether dietary flavonoid intake was associated with bone mineral density (BMD) and bone resorption in a large group of perimenopausal Scottish women. Over 3000 women completed a food frequency questionnaire as part of an osteoporosis screening study. The diets were analyzed for flavonoid intake using a food composition database. BMD was measured at the femoral neck (FN) and lumbar spine (LS) by dual-energy X-ray absorptiometry (DXA). Free pyridinoline (PYD) and deoxypyridinoline (DPD) were measured by high-performance liquid chromatography (HPLC) in second early morning fasted urine samples. The mean flavonoid intake of the diet was 307 ±199 mg/d. The catechin family contributed the most to flavonoid intakes (55%), and the flavones the least (<1%). Associations were found between energy-adjusted total flavonoid intakes and BMD at the FN and LS (FN r = 0.054, LS r = 0.036, p ≤ .05). Annual percent change in BMD was associated with intakes of procyanidins and catechins (p ≤ .05), and flavanones were negatively associated with bone-resorption markers (PYD r = -0.049, DPD r = -0.057, p ≤ .001). These associations were still seen after adjusting for confounders. It is concluded that dietary flavonoid intakes are associated with BMD, supporting the evidence from animal and cellular studies.