Bristow, SarahGamble, GregoryStewart, AHorne, AnneReid, Ian2017-03-012015-12British Journal of Nutrition 114(11):1868-1874 Dec 20150007-1145https://hdl.handle.net/2292/32018Recent evidence suggests that Ca supplements increase the risk of cardiovascular events, but the mechanism(s) by which this occurs is uncertain. In a study primarily assessing the effects of various Ca supplements on blood Ca levels, we also investigated the effects of Ca supplements on blood pressure and their acute effects on blood coagulation. We randomised 100 post-menopausal women to 1 g/d of Ca or a placebo containing no Ca. Blood pressure was measured at baseline and every 2 h up to 8 h after their first dose and after 3 months of supplementation. Blood coagulation was measured by thromboelastography (TEG) in a subgroup of participants (n 40) up to 8 h only. Blood pressure declined over 8 h in both the groups, consistent with its normal diurnal rhythm. The reduction in systolic blood pressure was smaller in the Ca group compared with the control group by >5 mmHg between 2 and 6 h (P≤0·02), and the reduction in diastolic blood pressure was smaller at 2 h (between-groups difference 4·5 mmHg, P=0·004). Blood coagulability, assessed by TEG, increased from baseline over 8 h in the calcium citrate and control groups. At 4 h, the increase in the coagulation index was greater in the calcium citrate group compared with the control group (P=0·03), which appeared to be due to a greater reduction in the time to clot initiation. These data suggest that Ca supplements may acutely influence blood pressure and blood coagulation. Further investigation of this possibility is required.Print-ElectronicItems in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmHumansOsteoporosis, PostmenopausalHypertensionBlood Coagulation DisordersCalcium CarbonateCalcium, DietaryDurapatiteCalcium CitrateRiskCohort StudiesDouble-Blind MethodBlood CoagulationBlood PressureDietary SupplementsAgedAged, 80 and overMiddle AgedPatient DropoutsNew ZealandFemaleBone Density Conservation AgentsElder Nutritional Physiological PhenomenaJournal Article10.1017/S0007114515003694Copyright: The author26420590http://purl.org/eprint/accessRights/RestrictedAccess1475-2662