Associations between High Protein Intake and Cardiovascular Diseases by Age Groups: A Cohort Study

The association between high protein intake and cardiovascular diseases (CVD) was conflicting and the role of age in this relationship was rarely studied. This study aimed to examine the association of high protein diet with the risk of CVD and the interaction of age in this association.

Participants from UK biobank (2007-2023) with at least 1 dietary questionnaire and without history of chronic diseases at baseline were included. High-protein diet was defined as protein intake ≥1.8 g·kg^-1·day^-1. The primary outcome was major adverse cardiovascular events (MACE). Cox regression analyses and restricted cubic spline (RCS) regression analyses were performed.

Among 19420 participants, the median (IQR) age was 54 (14) years and 14137 (72.8%) were women. With a follow-up of 256258.9 person-years, 967 MACEs occurred. After adjusting for sociodemographic and cardiovascular risk factors, participants with high-protein intake had higher risk of MACE compared with participants with low-protein intake (HR = 1.21, 95% CI, 1.02-1.44, P = 0.027). High-protein diet was also associated with higher risk of all-cause mortality, heart failure, myocardial infarction and CVD death (HR = 1.39, 95% CI, 1.17-1.65, P < 0.001; HR = 1.43, 95% CI, 1.07-1.92, P = 0.015; HR = 1.50, 95% CI, 1.07-2.10, P = 0.019; HR = 1.73, 95% CI, 1.12-2.65, P = 0.013, respectively). Among participants aged over 55 years, high protein intake was associated with higher risk of MACE (HR = 1.36, 95% CI, 1.13-1.63, P = 0.001). Whereas, among participants younger than 55 years, the association was not significant (HR = 0.75, 95% CI, 0.51-1.11, P = 0.099, P_interaction = 0.003). Similar interaction between age and high protein diet was witnessed in the association of high protein intake and stroke (P_interaction = 0.019).

Higher protein intake was related to higher incidence of MACE in participants over 55 years old, but the association was not evident in their counterparts younger than 55 years old.