Endocrine Abstracts

Introduction

The importance of calcium intake from dairy has been investigated in several studies with discrepant results. Meta-analyses have shown beneficial effects of dairy intake on cardiovascular health with an inverse association between intake and cardiovascular disease. However, a recent trial has suggested an increase in blood pressure in the hours following intake of 1000 mg of calcium citrate compared with placebo. So far, it has not been investigated whether milk intake causes similar effects on indices of cardiovascular health.

Materials and methods

We enrolled twenty postmenopausal women with vitamin D insufficiency aged between 60 and 80 years in this randomised crossover trial conducted during winter and spring. With at least ten days washout period in-between, the participants received either 500 ml of water or semi-skimmed milk with 200 µg of cholecalciferol added. Pulse wave analysis and velocity (PWV) were made twice using the SphygmoCor XCEL (AtCor Medical, Sydney, Australia): in the morning with the participants in a fasting state prior to and 4h after the intervention.

Results

Compared to water, milk increased plasma levels of ionized calcium by 1.61 pp (P = 0.023) and by 1.83 pp (P = 0.053) after 2h and 4h, respectively. Concomitantly, PTH levels decreased by 14.22 pp (P = 0.005) after 2 h and by 23.63 pp (P = 0.001) after 4 h. However, despite these changes, the two types of intervention did not cause changes as measured 4h after the intervention in indices of cardiovascular health in terms of PVW (P = 0.557), central diastolic blood pressure (P = 0.599), central systolic blood pressure (P = 0.403), mean arterial pressure (P = 0.671), pulse pressure (P = 0.443), aortic augmentation (P = 0.915), aortic augmentation index (P = 0.782), heart rate (P = 0.341), and pulse transit time (P = 0.987). We found no carry-over effect or period effect.

Discussion

The effects of dairy intake on cardiovascular health do not seem to occur acutely. Thus, the inverse relationship between dairy intake and cardiovascular disease seen in previous studies might be owing to long-term intake. Based on this study, milk intake is safe concerning immediate cardiovascular responses.