Animal And Plant Protein And Change In Blood Pressure During 15 Years Of Follow-Up: The Zutphen Elderly Study

Introduction: Data from randomized controlled trials and observational studies suggest that blood pressure (BP) is inversely related to dietary protein, especially plant protein. We examined whether intake of animal and plant protein were related to long-term changes in BP in a cohort of elderly men in the Netherlands. Methods: Analyses were based on data of 269 men participating in the Zutphen Elderly Study, who were examined in 1985, 1990, 1995 and 2000. Men did not use antihypertensive medication and were initially free of cardiovascular disease, diabetes mellitus and cancer. Diet was repeatedly assessed by trained dieticians using the cross-check dietary history method and BP was measured twice by trained research staff at every occasion. The associations of animal and plant protein (in tertiles) with 5-year BP change were obtained by a random intercept model, taking into account serial correlation and measurement error. Median values of tertiles (in en%) were 7.9, 9.7 and 12.8 for animal protein and 4.1, 4.9 and 6.0 for plant protein. Adjustments were made for age, measurement year, BMI, socioeconomic status, smoking, prescribed diet, alcohol intake, total energy intake and intake of carbohydrates, types of fat, minerals, dietary fibre and plant protein (in animal protein analysis) or animal protein (in plant protein analysis). Results: At baseline, men were 70±5 years old and BP was 147/84 mmHg. Mean intake was 10.2±2.7 en% for animal protein and 5.0±1.0 en% for plant protein. Animal protein was not associated with 5-year BP change (p>0.30). For plant protein intake, 5-year change in systolic BP was -3.30 mmHg (95% CI: [[Unable to Display Character: ‑]]6.39; [[Unable to Display Character: ‑]]0.20) and -2.56 mmHg (95% CI: -5.69; 0.57) in tertile 2 and tertile 3, respectively, compared to BP change in tertile 1. For diastolic BP, these changes were -1.61 mmHg (95% CI: [[Unable to Display Character: ‑]]3.34; 0.12) and -1.70 mmHg (95% CI: -3.45; 0.05), respectively. Conclusion: Plant protein, but not animal protein, was inversely associated with BP change during 15 years of follow-up in elderly men.