Epidemiological investigations of biomarker and dietary relationships with osteoporosis and fracture risk

• Main Author: Finck, Henriette
• Published: University of East Anglia 2015
• Subjects: 610
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.679175

Diet may aid osteoporosis and fracture prevention as it is modifiable, but limited evidence for a role of vitamin K1, vitamin C and iron exists, despite suggestions of potential underlying mechanisms. Positive associations between these nutrients and bone health have been reported in population studies; however, evidence is scarce in men, in British populations, for nutrient status and for fracture risk. Combining measures of dietary intake with biomarkers may limit errors associated with establishing population intakes, but no such studies exist in bone health. Therefore, this thesis aimed to investigate micronutrient intakes and blood measures and i) their cross-sectional associations with heel ultrasound and ii) their prospective associations with fracture risk in a sub-set of EPIC-Norfolk participants. An additional aim was to explore means of limiting the impact of measurement errors on the association between vitamin C and bone health. The main results showed significant associations between higher intakes of vitamin K1 and C and 0.6-5.5% higher heel ultrasound in both sexes, and additionally with total and plant-based iron intakes in women (0.4-5.8%). Moreover, upper versus lower quintiles of plasma vitamin C concentrations in men showed significant associations with reduced fracture risk at the hip (HR:0.35, 95%CI:0.16-0.80) and spine (HR:0.26, 95%CI:0.10-0.69). In women, upper versus lower quintiles of vitamin K1 intake (HR:0.47, 95%CI:0.24-0.91), total iron intake (HR:0.41, 95%CI:0.21-0.79), animal-based iron intake (HR:0.44, 95%CI:0.24-0.82) and serum ferritin concentrations (HR:0.30, 95%CI:0.14-0.64) were significantly inversely associated with spine fracture risk. In contrast, upper versus lower quintiles of animal iron intake in men was significantly associated with higher hip fracture risk (HR:2.29, 95%CI:1.11-4.73). . In further investigations, combining vitamin C intake and plasma status strengthened the associations with bone health in men, but not in women. In conclusion, this thesis provides novel insights into the role of diet in osteoporosis and fracture prevention.