Protein intake trends and conformity with the Dietary Reference Intakes in the United States: analysis of the National Health and Nutrition Examination Survey, 2001-2014

Background: Systematic analysis of dietary protein intake may identify demographic groups within the American population that are not meeting the Dietary Reference Intakes (DRIs). Objective: This cross-sectional study analyzed protein intake trends (2001-2014) and evaluated recent conformity to the DRIs (2011-2014) according to age, sex, and race or ethnicity in the US population. Design: Protein intakes and trends during 2-y cycles of NHANES 2001-2014 (n = 57,980; >= 2 y old) were calculated as absolute (grams per day) and relative [grams per kilogram of ideal body weight (IBW) per day] intakes and as a percentage of total energy. Sex and race or ethnicity [Asian, Hispanic, non-Hispanic black (NHB), and non-Hispanic white (NHW)] differences were determined for protein intake and percentage of the population below the Estimated Average Requirement (EAR) and Recommended Dietary Allowance, and above and below the Acceptable Macronutrient Distribution Range (AMDR). Results: Usual protein intakes (mean +/- SE) averaged from 55.3 +/- 0.9 (children aged 2-3 y) to 88.2 +/- 1.1 g/d (adults aged 19-30 y). Protein comprised 14-16% of total energy intakes. Relative protein intakes averaged from 1.10 +/- 0.01 (adults aged >= 71 y) to 3.63 +/- 0.07 g . kg IBW-1 . d(-1) (children aged 2-3 y), and were above the EAR in all demographic groups. Asian and Hispanic populations aged >19 y consumed more relative protein (1.32 +/- 0.02 and 1.32 +/- 0.02 g . kg IBW-1 . d(-1), respectively) than did NHB and NHW (1.18 +/- 0.01 g . kg IBW-1 . d(-1)). Relative protein intakes did not differ by race or ethnicity in the 2-18 y population. Adolescent (aged 14-18 y) females and older (aged >= 71 y) NHB men had the largest population percentages below the EAR (11% and 13%, respectively); <1% of any demographic group had intakes above the AMDR. Conclusions: The majority of the US population exceeds minimum recommendations for protein intake. Protein intake remains well below the upper end of the AMDR, indicating that protein intake, as a percentage of energy intake, is not excessive in the American diet. This trial was registered at www.isrctn.com as ISRCTN76534484.