Efeitos agudos do cálcio suplementar sobre a glicemia, lipemia, pressão arterial e reatividade microvascular cutânea durante o período pós-prandial em mulheres obesas

Abstract

Calcium supplements are widely used mainly by women and with meals. There is evidence that supplemental calcium (SC) is associated with increased risk of cardiovascular events and the proposed mechanism is the acute increase in serum calcium concentration that occurs after the ingestion of SC. The elevation of serum calcium may promote vascular calcification, but other mechanisms may be involved. Aims: To assess the acute effects of SC on calcium, glucose and lipid metabolism; BP; and microvascular function during the postprandial period in obese women. Randomized crossover clinical trial involving 16obese women. All subjects ingested on different days (with an interval of 1 to 2 week between them), two high fat meals presenting similar amounts of energy (695 kcal) and macronutrients. The meals differed only in calcium content: low calcium (LCM; 41mg) and rich in SC (RSCM; 541mg) from 1,250 mg of calcium carbonate. The moment of the intake of the meal was regarded as minute 0 (T0). The evaluations were performed at the following times: anthropometry at -45 minute, BP from -15 to 120 minutes, vascular function at -30 and 120 minutes, and laboratory at minutes 0, 120 (T120) and 240 (T240). Laboratory evaluation included the dosage of serum calcium, parathyroid hormone (PTH), glucose, insulin, total cholesterol and fractions, triglycerides, high sensitive C-reactive protein and uric acid. Vascular function was assessed by Laser Speckle Contrast Imaging (PSI-NR® Pericam). The BP was assessed continuously through the digital photoplethysmography (Finometer Pro®). ANOVA for repeated measures was used to evaluate the intra and inter-meals changes. Participants had a mean age of 34.31 ± 2.07 years and a body mass index of 34.16 ± 0.92 kg/m2. After the ingestion of both meals there was no significant elevation of blood glucose, but there was a significant increase (p <0.01) in insulin. Total cholesterol increased only after the LCM (p = 0.004), while the LDL-cholesterol decreased only after RSCM (p = 0.01). Triglycerides increased after the 2 meals (p <0.0001). After RSCM total serum calcium increased (T0 = 8.97 ± 0.15; T120 = 9.17 ± 0.17; T240 = 9.52 ± 0,19mg/dL; p = 0.01), while PTH decreased (T0 = 41.37 ± 3.61, 26.88 ± 2.86 = T120; T240 = 32.21 ± 4,10pg/ mL; p = 0.0009). Both the amplitude and the area under the curve of cutaneous vascular conductance showed a significant reduction only after the LCM. After the LCM there was a significant increased (p <0.001) in systolic and diastolic BP while after RSCM there was a significant elevation only in systolic BP (p <0.001). The other variables evaluated in the study showed no significant changes. The comparative analysis between the 2 meals showed that the rise in serum calcium and the reduction in PTH were significantly higher after RSCM, with no difference between the two meals regarding other variables. In obese women, during the postprandial period, SC is associated with increase in serum calcium and decrease in PTH showing no deleterious effects on BP and microvascular function.