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.
Level 4 - case-series / case-control
Cross-sectional survey analysis (NHANES 2001-2014)
PubMed 29931213 · doi:10.1093/ajcn/nqy088
What was done
The authors analyzed cross-sectional dietary recall data from 2-year cycles of the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2014 in 57,980 US participants aged 2 years and older. They evaluated absolute protein intake (g/d), relative intake per kilogram of ideal body weight (g · kg IBW⁻¹ · d⁻¹), and percentage of total energy. Intakes from 2011 to 2014 were compared across age, sex, and race or ethnicity (Asian, Hispanic, non-Hispanic Black, non-Hispanic White) against Dietary Reference Intakes: the Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), and Acceptable Macronutrient Distribution Range (AMDR).
What was found
Usual protein intake ranged from 55.3 ± 0.9 g/d in children aged 2-3 years to 88.2 ± 1.1 g/d in adults aged 19-30 years, accounting for 14-16% of total energy. Relative protein intake averaged from 1.10 ± 0.01 g · kg IBW⁻¹ · d⁻¹ (adults ≥71 years) to 3.63 ± 0.07 g · kg IBW⁻¹ · d⁻¹ (children 2-3 years), exceeding the EAR across all demographic groups. Among adults >19 years, Asian and Hispanic individuals consumed more relative protein (both 1.32 ± 0.02 g · kg IBW⁻¹ · d⁻¹) than non-Hispanic Black and non-Hispanic White individuals (1.18 ± 0.01 g · kg IBW⁻¹ · d⁻¹). Adolescent females (14-18 years) and older non-Hispanic Black men (≥71 years) had the largest proportions below the EAR (11% and 13%, respectively). Less than 1% of any demographic group had intakes above the AMDR.
Why it matters
This study provides population-level benchmark data showing that while the majority of Americans meet minimum protein recommendations without consuming excessive amounts, specific sub-populations—notably adolescent girls and older Black men—remain at elevated risk for protein inadequacy.
Limits
The study is cross-sectional and relies on self-reported dietary recalls, which are subject to recall bias and misreporting. Intake adequacy was evaluated relative to ideal body weight rather than individual lean body mass or physiological outcomes. Protein source (animal vs. plant) and protein distribution across meals were not described in the abstract.
Cited by
- supports Average daily protein intake among adults in the United States is approximately 1.2 grams per kilogram of body weight.