| Hypertension is a global public-health problem.It is estimated that almost 1 in 3pepople affected by hypertension worldwide.Hypertension can cause endothelial dysfunction,vascular intimal thickening,even the formation of atherosclerotic plaque,also can change the function and structure of the left ventricular.It is reported that whey peptides can decrease blood pressure by inhibiting angiotensin-converting enzyme(ACE).Compared with whey peptides,whey protein have more beneficial effect,whey protein can be enzymatic hydrolyzed into ACE inhibitory activity peptides by pepsin and trypsin in vitro.We hypothesized that whey protein could be degraded into active peptides in human gut and exert antihypertensive effects.Objective:We aimed to investigate whether intact whey protein lower blood pressure and other risk markers of cardiovascular disease.Methods:1.Randomized controlled trialThe trial was a randomized,controlled intervention study.Sixty-five participants were randomly assigned to consume 2×15 g whey protein/d,2×15 g maltodextrin(control)/d for 12 wk.During the intervention,we examined the following index:blood pressure,endothelial function,carotid arterial intima-media thickness(IMT)left ventricular systolic and diastolic function,body weight and body composition,serum ACE,angiotension II,chronic inflammation factors,oxidation markers and metabolic index.2.Meta analysisPubMed and Cochrane database were searched for the randomized controlled trials reporting the relationship between milk protein and blood pressure until December 2016,calculation and analysis the combined effect and 95%confidence intervals(95%CI)of milk protein on systolic blood pressure and diastolic blood pressure.PubMed and Cochrane database were searched for the randomized controlled trials reporting the relationship between milk protein and inflammatory factors C-reactive protein(CRP),interleukin-6(IL-6),tumor necrosis factor alpha(TNF-α)until December2016,calculation and analysis the combined effect and 95%confidence intervals(95%CI)of milk protein on plasma CRP,IL-6 and TNF-α.Results:Randomized control trial1.After the intervention of whey protein,systolic blood pressure(SBP)decreased from 133.3±6.5mmHg to 128.2±6.9mmHg,compared with the control group,there was a trend of antihypertensive effects of whey protein on SBP,but did not reach statistical difference(P=0.052).The SBP of overweight and obese patients was significantly lower than that of the control group after whey protein supplementation(P=0.033).Diastolic blood pressure,plasma ACE and angiotension II concentrations did not change significantly.2.Compared with the control group,flow mediated dilation(FMD)was significantly improved in whey protein group(5.4±8.9 vs.0.7±7.4,P=0.04),but the levels of endothelium-1 and nitric oxide,carotid intima-media thickness,left ventricular diastolic and systolic function were not significantly changed.3.Compared with the control group,the content of fat tissue(-1.05±0.93 vs.-0.08±0.98,P=0.005)and the percentage of body fat(-1.18±1.15 vs.-0.03±1.22,P=0.011)were significantly decreased in whey protein group.For overweight and obese patients,content of fat tissue(-1.44±0.89 vs.-0.19±0.91,P=0.01)and the percentage of body fat(-1.46±0.98 vs.-0.19±0.93,P=0.016)were significantly decreased in whey protein group.For normal weight patients,body weight and body composition index were not significantly changed compared with control group.4.Compared with the control group,the improvement of adhesion molecule E-selection was more obvious.The level of oxidative damage index malondialdehyde in whey protein group was significantly lower after intervention.The levels of plasma inflammatory factors,oxidation markers and metabolic index were not significantly improved.5.The change of SBP was related to the change of body weight,body fat and waist-circumstance.The change of FMD was significantly correlated with the change of visceral fat and waist-circumstance.The change of FMD had a tendency correlated with the change of body fat.Meta analysis1.According to the inclusion and exclusion criteria,eight related studies were identified for this meta-analysis.The results showed that the milk protein significantly lower SBP compared with the control group,the combined effect was-3.22 mmHg(95%CI-4.77,-1.67),mild heterogeneity existed(I~2=31.3%,P=0.149),diastolic blood pressure did not change significantly,the combined effect was-0.72 mmHg(95%CI-2.09,0.66),no heterogeneity existed(I~2=0%,P=0.558).Stratified analysis showed that the SBP was decreased in each group,but there was a certain degree of heterogeneity.2.According to the inclusion and exclusion criteria,six related studies were identified for this meta-analysis.The random effects model calculation showed that the milk protein did not significantly lower plasma CRP level compared with the control group,the combined effect was-0.23mg/L(95%CI:-0.75,0.29),there is heterogeneity existed(I~2=63.3,P=0.018).Stratification analysis had no significant effect on the results.Plasma IL-6 and TNF-αlevels did not change significantly compared with control group,the combined effect were-0.19mg/L(95%CI:-0.43,0.05)and 0.06mg/L(95%CI:-0.11,0.23).Conclusion:1.Whey protein can improve blood pressure in overweight or obese patients with hypertension,can improve the vascular endothelial function in hypertension patients,which were associated with weight and fat loss after whey protein intervention.2.Whey protein can reduce the content of adipose tissue in overweight and obese patients,have no obvious effects on lean body mass,but helps to avoid loss of lean tissue during weight reduction.3.Whey protein have no effects on carotid IMT,left ventricular diastolic and systolic function in patients with hypertension.4.Meta analysis showed that the milk protein can significantly decrease SBP,but have no significant effect on diastolic blood pressure,serum CRP,IL-6 and TNF-αlevels. |
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