Dietary protein and risk of hypertension in a Dutch older population: the Rotterdam study

Background Several observational studies suggest an inverse association of protein with blood pressure (BP). However, little is known about the role of dietary protein from specific sources in BP. Method We examined the relation between several types of dietary protein (total, plant, animal, dairy, meat, grain, fish, soy, and nut) and incident hypertension in 2241 participants from the Rotterdam Study, aged at least 55 years, who were free of hypertension at baseline. Hazard ratios, with 95% confidence intervals (CIs), for incident hypertension during 6 years of follow-up were obtained per standard deviation (SD) of energy-adjusted intake of protein. Hazard ratios were adjusted for age, sex, body mass index (BMI), baseline systolic blood pressure (SBP) smoking, educational level, alcohol, intake of carbohydrates, other nutrients, and other types of protein (if applicable). We conducted stratified analyses by age (cut-off 70 years), sex, and BMI (cut-off 25 kg/m(2)). Results The risk of hypertension in the total cohort (1113 cases) was not related to intake of total protein or types of protein (all hazard ratios similar to 1.00 per SD). Sex and BMI did not significantly modify the associations of dietary protein with hypertension. In 559 participants aged at least 70 years, the intake of animal protein was positively related to risk of hypertension (hazard ratio 1.37 per SD, 95% CI 1.09-1.72). For participants aged below 70 years no association was found (hazard ratio 0.92, 95% CI 0.81-1.06). Conclusion Total dietary protein or types of protein are not related to incident hypertension in this older population. In the more aged, however, high intake of animal protein may increase the risk of hypertension, which warrants further investigation. J Hypertens 28: 2394-2400 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.