Acute effects of whey protein, alone and mixed with other macronutrients, on blood pressure and heart rate in older men

Background Caloric supplements are increasingly used by older people, aiming to increase their daily protein intake. These high caloric drinks, rich in glucose and whey-protein in particular, may result in potential harmful decreases in blood pressure (BP). The effect of ingesting whey-protein with glucose and fat on BP is unknown. It has also been assumed that the maximum fall in systolic blood pressure occurs within 2 h of a meal. Methods This study aimed to determine in older men, the effects of whey-protein, alone and mixed with other macronutrients, on systolic (SBP) and diastolic (DBP) blood pressure and heart rate (HR) in older men for 3 h. Thirteen older men (age 75 ± 2yrs; body mass index (BMI) 25.6 ± 0.6 kg/m 2 ) ingested a drink on separate study days: (i) 70 g whey-protein (P 280 ) ; (ii) 14 g whey-protein, 28 g carbohydrate, 12.4 g fat (M 280 ); (iii) 70 g whey-protein, 28 g carbohydrate, 12.4 g fat (M 504 ); or (iv) a non-caloric control drink (C). Results SBP decreased after all three nutrient drinks compared to the C, with the greatest reduction after the M 504 drink ( P = 0.008). Maximal decreases in SBP (C: -14 ± 2 mmHg, P 280 : -22 ± 2 mmHg, M 280 : -22 ± 4 mmHg, M 504 : -24 ± 3 mmHg) occurred about 2 h after drink ingestion and this fall was sustained thereafter (120-180 min: P 280 and M 504 vs. C P < 0.05). Maximum DBP decreases and HR increases occurred after M 504 , with no differences between the effects of the P 280 and M 280 drinks. Conclusions The effects of whey-protein containing drinks to lower BP and increase HR appear to be primarily dependent on their energy content rather than macronutrient composition and may persist for at least 3 h after ingestion,. Pure whey-protein drinks may represent the best approach to maximize protein intake without increasing the potential for deleterious BP falls in older people. Trial registration ACTRN12614000846628 , 14/03/2019.