Associations of plant and animal protein intake with 5-year changes in blood pressure: The Zutphen Elderly Study

Background and aim The aim of the present study was to investigate the association of plant and animal protein intake with 5-year changes in blood pressure (BP) level. Methods and results Analyses were based on 702 observations of 272 men participating in the Zutphen Elderly Study. Men did not use antihypertensive medication and were initially free of cardiovascular disease, diabetes mellitus and cancer. Physical and dietary examinations were performed in 1985, 1990, 1995, and 2000. Diet was assessed using the cross-check dietary history method. Men were categorised into tertiles according to their plant and animal protein intake. BP was measured twice at each examination. The associations of plant and animal protein intake with 5-year changes in BP level were investigated by a random intercept model with first-order autoregressive (AR [1]) serial correlation and a nugget effect. Adjustments were made for age, examination year, BMI, socioeconomic status, smoking, physical activity, prescribed diet, alcohol consumption and intake of energy and nutrients. In 1985, men were 70.1 ± 4.6 years old and had a mean BP of 147/84 mmHg. Mean protein intake was 15 en%, of which one-third consisted of plant protein. The higher-intake tertiles of plant protein intake were associated with a mean 5-year change of -2.9 mmHg (95% CI: -5.6, -0.2) systolic and -1.7 mmHg (95% CI: -3.2, -0.2) diastolic, compared with the lowest-intake tertile. No associations were observed for animal protein intake. Conclusion Intake of plant protein, but not animal protein, was inversely associated with 5-year changes in BP level in elderly men.