Abstract:Calcium supplements have been associated with an increased risk of cardiovascular events. However, the validity of these findings has been questioned. A major concern is that the mechanism underlying an increase in cardiovascular events has not been demonstrated. Calcium initiates cardiac and vascular contraction following influx of calcium into cardiac and smooth muscle from extracellular fluid. We have investigated whether the acute rise in serum calcium following calcium supplement administration is associa… Show more
“…35 In healthy adults, 1000 mg of a single dose of calcium citrate has been demonstrated to acutely elevate serum calcium concentrations and subsequently improve pulse rate and the augmentation index relative to baseline. 36 The cardiovascular effects of this acute elevation in circulating calcium, if recurring on a daily basis over an extended period of time, are not well understood.…”
BackgroundCalcium is a shortfall essential nutrient that has been a mainstay of osteoporosis management. Recent and limited findings have prompted concern about the contribution of calcium supplementation to cardiovascular risk. A proposed mechanism is through the acceleration of coronary artery calcification. Determining causality between calcium intake and coronary artery calcification has been hindered by a lack of sensitive methodology to monitor early vascular calcium accumulation. The primary study aim was to assess the impact of high calcium intake on coronary artery calcification using innovative calcium tracer kinetic modeling in Ossabaw swine with diet-induced metabolic syndrome. Secondary end points (in vitro wire myography, histopathology, intravascular ultrasound) assessed coronary disease.Methods and ResultsPigs (n =24; aged ≈15 months) were fed an atherogenic diet with adequate calcium (0.33% by weight) or high calcium (1.90% from calcium carbonate or dairy) for 6 months. Following 5 months of feeding, all pigs were dosed intravenously with 41Ca, a rare isotope that can be measured in serum and tissues at a sensitivity of 10−18 mol/L by accelerator mass spectrometry. Kinetic modeling evaluated early coronary artery calcification using 41Ca values measured in serial blood samples (collected over 27 days) and coronary artery samples obtained at sacrifice. Serum disappearance of 41Ca and total coronary artery 41Ca accumulation did not differ among groups. Secondary end points demonstrated no treatment differences in coronary artery disease or function.ConclusionThere was no detectable effect of high calcium diets (from dairy or calcium carbonate) on coronary artery calcium deposition in metabolic syndrome swine.
“…35 In healthy adults, 1000 mg of a single dose of calcium citrate has been demonstrated to acutely elevate serum calcium concentrations and subsequently improve pulse rate and the augmentation index relative to baseline. 36 The cardiovascular effects of this acute elevation in circulating calcium, if recurring on a daily basis over an extended period of time, are not well understood.…”
BackgroundCalcium is a shortfall essential nutrient that has been a mainstay of osteoporosis management. Recent and limited findings have prompted concern about the contribution of calcium supplementation to cardiovascular risk. A proposed mechanism is through the acceleration of coronary artery calcification. Determining causality between calcium intake and coronary artery calcification has been hindered by a lack of sensitive methodology to monitor early vascular calcium accumulation. The primary study aim was to assess the impact of high calcium intake on coronary artery calcification using innovative calcium tracer kinetic modeling in Ossabaw swine with diet-induced metabolic syndrome. Secondary end points (in vitro wire myography, histopathology, intravascular ultrasound) assessed coronary disease.Methods and ResultsPigs (n =24; aged ≈15 months) were fed an atherogenic diet with adequate calcium (0.33% by weight) or high calcium (1.90% from calcium carbonate or dairy) for 6 months. Following 5 months of feeding, all pigs were dosed intravenously with 41Ca, a rare isotope that can be measured in serum and tissues at a sensitivity of 10−18 mol/L by accelerator mass spectrometry. Kinetic modeling evaluated early coronary artery calcification using 41Ca values measured in serial blood samples (collected over 27 days) and coronary artery samples obtained at sacrifice. Serum disappearance of 41Ca and total coronary artery 41Ca accumulation did not differ among groups. Secondary end points demonstrated no treatment differences in coronary artery disease or function.ConclusionThere was no detectable effect of high calcium diets (from dairy or calcium carbonate) on coronary artery calcium deposition in metabolic syndrome swine.
“…The time period between 90 and 150 s after deflation was used for automated calculation of the reactive hyperaemia index . The average day‐to‐day CV for reactive hyperaemia index at our institution is 11·4% …”
Prednisolone-induced insulin resistance is not associated with postprandial vascular dysfunction in patients with rheumatoid arthritis. Reduced sympathetic activity may contribute to the reduction in postprandial arterial stiffness with acute prednisolone.
“…Increased arterial stiffness and impaired endothelial vasodilator function resulting from high circulating levels of ionised Ca associated with Ca supplementation could also lead to vascular damage (58) . However, Burt et al (64) examined the acute effect of 1000 mg of Ca citrate on arterial stiffness in adults aged 50 years and above and found no significant change in PWV 3 h following supplementation. Arterial stiffness, as measured by the 'gold-standard' cfPWV, is an overall indicator of vascular health and is strongly associated with the development of atherosclerosis at different sites of the arterial system and CVD and cardiovascular events (28,29,66,67) .…”
Whether supplemental Ca has similar effects to dietary Ca on vascular and bone markers is unknown. The present trial investigated the feasibility of applying dietary and supplemental interventions in a randomised-controlled trial (RCT) aiming to estimate the effect of supplemental Ca as compared with dietary Ca on vascular and bone markers in postmenopausal women. In total, thirteen participants were randomised to a Ca supplement group (CaSuppl) (750 mg Ca from CaCO 3 + 450 mg Ca from food + 20 µg vitamin D supplement) or a Ca diet group (CaDiet) (1200 mg Ca from food + 10 µg vitamin D supplement). Participants were instructed on Ca consumption targets at baseline. Monthly telephone follow-ups were conducted to assess adherence to interventions (±20 % of target total Ca) using the multiple-pass 24-h recall method and reported pill count. Measurements of arterial stiffness, peripheral blood pressure and body composition were performed at baseline and after 6 and 12 months in all participants who completed the trial (n 9). Blood and serum biomarkers were measured at baseline and at 12 months. Both groups were compliant to trial interventions (±20 % of target total Ca intake; pill count ≥80 %). CaSuppl participants maintained a significantly lower average dietary Ca intake compared with CaDiet participants throughout the trial (453 (SD 187) mg/d v. 1241 (SD 319) mg/d; P < 0·001). There were no significant differences in selected vascular outcomes between intervention groups over time. Our pilot trial demonstrated the feasibility of conducting a large-scale RCT to estimate the differential effects of supplemental and dietary Ca on vascular and bone health markers in healthy postmenopausal women.Key words: Dietary interventions: Calcium: Arterial stiffness: Postmenopausal women Adequate intakes of Ca and vitamin D are essential for optimal bone health throughout adulthood to prevent osteoporosis and related fractures (1)(2)(3)(4)(5)(6) . Current dietary reference intakes for Ca have been established by the Institute of Medicine for women over 50 years of age -that is, the Estimated Average Requirement (EAR), RDA and Tolerable Upper Intake Level (UL) are 1000, 1200 and 2000 mg/d, respectively (7) . However, adequate intake of Ca can be difficult to achieve through dietary sources alone (8,9) .According to the National Health and Nutrition Examination Survey 2003-2006 data, less than 10 % of American women over 50 years of age reached an intake of 1200 mg/d of Ca from food alone (8) . Similarly, over 80 % of Canadian women over 50 years of age had a Ca intake <1000 mg/d from dietary sources according to the 2004 Canadian Community Health Survey (9) . Thus, to ensure adequate total Ca intake for skeletal integrity, Ca supplements are widely recommended (10,11) . Collectively, data from North America documented that 49-67 % of women aged 50-70 years and 60-65 % of those over 71 years of age reported using supplements that contain Ca (8,9) .Ca supplementation is generally well tolerated but can be associated with ...
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