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.