Impact of High Calcium Intake from Calcium Carbonate or Dairy on Cardiovascular Function, Coronary Artery Calcification and Coronary Artery Disease Burden in Ossabaw Miniature Swine
Abstract
Recent secondary analyses have associated supplemental calcium use with increased risk for myocardial infarction and cardiovascular-related death in healthy, older adults. Subsequent concern over the safety of calcium supplements has spurred a calcium controversy, because calcium is a shortfall essential nutrient that is critical for bone health and a mainstay of osteoporosis prevention and treatment. The proposed mechanism by which calcium intake may detriment cardiovascular health is through the acceleration of coronary artery calcification (CAC), a clinical indicator of coronary artery disease (CAD) that has been associated with mortality risk. However, causal evidence to support this hypothesis is lacking. Determining causality between calcium intake and cardiovascular risk has been hindered by the long intervention period necessary to monitor disease progression in human populations and a lack of sensitive outcome measures to detect early vascular calcification. The aim of this research was to assess the effect of high calcium consumption from calcium carbonate or dairy on cardiovascular function, CAD burden and coronary artery calcium deposition in the Ossabaw swine, a model that mimics human metabolic syndrome and CAD when fed an atherogenic diet. Pigs (n=24) were maintained on an atherogenic diet and randomized to one of three calcium treatments including control calcium (0.5% Ca by weight), high calcium from calcium carbonate (2% Ca), or high calcium from dairy (2% Ca) for 6 months. To sensitively assess CAC with calcium tracer kinetics, pigs were dosed with the rare isotope, 41Ca, that can be measured in blood and tissues at a sensitivity of 10-18 M by Accelerator Mass Spectrometry (AMS). More traditional measures of cardiovascular health and disease were also utilized including computed tomography (CT), intravascular ultrasound (IVUS), histopathology and in vitro wire myography. 41Ca:Ca accumulation measured in the coronary arteries did not differ by calcium treatment. Further, calcium tracer kinetic modeling revealed the rates of calcium transport from blood to the coronary arteries were similar among groups. These findings were corroborated by collective data obtained through CT, IVUS and histopathology that showed no treatment differences in atherosclerotic or calcified plaque coverage of the coronary arteries. Further analysis of coronary artery endothelial and vascular smooth muscle cell function by in vitro wire myography revealed no differences among calcium treatment groups. High calcium intakes from calcium carbonate or dairy did not alter cardiovascular function or aggravate atherosclerotic or calcified plaque deposition in coronary arteries of Ossabaw miniature swine fed an atherogenic diet.
Degree
M.S.
Advisors
Weaver, Purdue University.
Subject Area
Nutrition
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