Abstract and Introduction
Objective: The importance of calcium intake from dairy in regard to cardiovascular health has been investigated in several studies with discrepant results. Hence, we aim to investigate the immediate effects of milk intake on cardiovascular function.
Design: A randomized crossover study with at least 10 days for washout between the two interventions, 500 ml of water with 200 μg of cholecalciferol or 500 ml of semi-skimmed milk containing approximately 600 mg of calcium with 200 μg of cholecalciferol.
Patients: Twenty community-based postmenopausal women aged 60–80 years.
Measurements: Parathyroid hormone and ionized calcium were measured at baseline and after 2 and 4 h on each study day. Pulse wave analysis and velocity were measured at baseline and after 4 h on each study day.
Results: Compared to water, milk intake increased ionized calcium levels by 0.02 mmol/L (p = .029) and decreased parathyroid hormone levels by 1.78 pmol/L (p < .001). The two interventions caused no changes as measured 4 h after the intervention in the following indices of cardiovascular health; pulse wave velocity, brachial diastolic or systolic blood pressure, central diastolic or systolic blood pressure, mean arterial pressure, pulse pressure, augmentation pressure, augmentation index, heart rate or pulse transit time.
Conclusions: Despite significant changes in calcium homeostasis with increased levels of ionized calcium following milk intake, no acute effects seem to occur on measures of cardiovascular health.
Over the past decade, the importance of calcium intake in general and calcium intake from milk products and supplementation in particular has been investigated in a number of studies showing discrepant results. A Cochrane meta-analysis suggested an overall beneficial effect of increased calcium intake from milk products and calcium supplements. Another meta-analysis found an increased risk of myocardial infarction among participants in randomized trials receiving calcium supplements. Likewise, a Swedish community-based cohort study found that a high intake of calcium (>1400 mg/day) in women was associated with higher death rates from all causes and cardiovascular disease (CVD) but not from stroke. A recent randomized crossover trial has suggested a relative increase in blood pressure in the hours following intake of 1000 mg of calcium citrate compared with placebo. In contrast, Burt et al. found no effect on arterial stiffness and a decrease in arterial wave reflection (augmentation index [Aix]) in the hours following intake of 1000 mg of calcium as citrate. So far, it has not been investigated whether milk intake has similar effects on indices of cardiovascular health. The current discrepancy in research on the cardiovascular effect of calcium intake is concerning given the status milk consumption enjoys in today's western societies.
Arterial stiffness is a strong predictor of CVD, future cardiovascular events and all-cause mortality.[6,7] It can be measured noninvasively by pulse wave velocity (PWV), which is considered the gold standard.[8,9] Carotid-femoral PWV reflects the arterial stiffness in aorta, but it is also a dynamic measure that can change within 90 min after administration of antihypertensiva. An increase in PWV by 1 m/s corresponds to an age-, sex-, and risk factor–adjusted risk increase of 14% in cardiovascular events.
The aim of this study was to investigate the immediate effects of milk intake on cardiovascular indices by measuring arterial stiffness. Our null hypothesis was that cardiovascular indices are not affected by milk intake.
Clin Endocrinol. 2022;96(6):812-818. © 2022 Blackwell Publishing