Diets higher in animal and plant protein are associated with lower adiposity and do not impair kidney function in US adults
Claire E Berryman Am J Clin Nutr September 2016 vol. 104 no. 3 743-749
Background: Higher-protein diets are associated with decreased adiposity and greater HDL cholesterol than lower protein diets. Whether these benefits can be attributed to a specific protein source (i.e., nondairy animal, dairy, or plant) is unknown, and concerns remain regarding the impact of higher-protein diets on kidney function.
Objective: The objective of this study was to evaluate trends of protein source on markers of cardiometabolic disease risk and kidney function in US adults.
Design: Total, nondairy animal, dairy, and plant protein intake were estimated with the use of 24-h recall data from NHANES 2007–2010 (n = 11,111; ≥19 y). Associations between source-specific protein intake and health outcomes were determined with the use of models that adjusted for sex, race and ethnicity, age, physical activity, poverty-to-income ratio, individual intake (grams per kilogram) for each of the other 2 protein sources, body mass index (BMI) (except for weight-related variables), and macronutrient (carbohydrate, fiber, and total and saturated fat) intake.
Results: Mean ± SE total protein intake was 82.3 ± 0.8 g/d (animal: 37.4 ± 0.5 g/d; plant: 24.7 ± 0.3 g/d; and dairy: 13.4 ± 0.3 g/d). Both BMI and waist circumference were inversely associated [regression coefficient (95% CI)] with animal [−0.199 (−0.265, −0.134), P < 0.0001; −0.505 (−0.641, −0.370), P < 0.0001] and plant [−0.346 (−0.455, −0.237), P < 0.0001; −0.826 (−1.114, −0.538), P < 0.0001] protein intake. Blood urea nitrogen concentrations increased across deciles for animal [0.313 (0.248, 0.379), P < 0.0001; decile 1–10: 11.6 ± 0.2 to 14.9 ± 0.3 mg/dL] and dairy [0.195 (0.139, 0.251), P < 0.0001; decile 1–10: 12.7 ± 0.2 to 13.9 ± 0.2 mg/dL] but not plant protein intake. Glomerular filtration rate and blood creatinine were not associated with intake of any protein source.
Conclusions: Diets higher in plant and animal protein, independent of other dietary factors, are associated with cardiometabolic benefits, particularly improved central adiposity, with no apparent impairment of kidney function.