Percentage of total protein intake from animal and plant sources differ by some demographic characteristics but not others among U.S. adults: What We Eat in America, NHANES 2015–2018

Authors: Hoy, Mary; Murayi, Theophile; Sebastian, Rhonda; Moshfegh, Alanna

Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2025
Publication Date: 3/29/2025
Citation: Hoy, M.K., Murayi, T., Sebastian, R.S., Moshfegh, A.J. 2025. Percentage of total protein intake from animal and plant sources differ by some demographic characteristics but not others among U.S. adults: What We Eat in America, NHANES 2015–2018. Journal of Food Composition and Analysis. 143. Article 107559. https://doi.org/10.1016/j.jfca.2025.107559.
DOI: https://doi.org/10.1016/j.jfca.2025.107559

Interpretive Summary: Dietary guidance recommends replacing some animal protein in the diet with plant proteins. Demographic characteristics may be related to intake of animal and plant protein. The objective of this study is to describe protein intake from plant and animal sources by demographic characteristics. The proportion of total protein from animal and plant sources were estimated for each food in the Food and Nutrient Database for Dietary Studies (FNDDS) 2017-2018 and 2019-2020, then applied to the Day 1 dietary intakes of adults 19+ years (N=9811) in WWEIA, NHANES 2017-March 2020 Prepandemic. Proportions were compared by demographic characteristic. Overall, about two-thirds of protein intake is from animal sources (primarily, Meat, Poultry, Dairy) and one-third is from plant sources (primarily Grains). Proportions from animal sources are higher among males vs females, and among those 19-59 vs 60+ years, and are lower among non-Hispanic (NH) Asian adults and higher among Hispanic adults compared to NH-White and NH-Black adults. There are no differences by income. A slightly higher percentage of those with greater than a high school education consumed Legumes, Nuts, and Soy compared to those with high school education or less. There are modest differences in the proportions of total protein from animal and plant foods by demographic characteristics which may inform targeted nutrition messaging.

Technical Abstract: Dietary guidance emphasizes replacing some animal protein in the diet with plant protein. It is unclear if the percentage of protein from these sources vary among demographic groups in the U.S. In this study, animal and plant protein content were estimated for every food reported in the nationally representative What We Eat in America, National Health and Nutrition Examination Survey 2015–2018. Using one day of dietary recall data from adults 19'+'years (n'='9813), percentages of protein intake from animal and plant sources were compared by sex, age, race/ethnicity, family income, and educational level. Protein intake percentages from animal and plant sources are 67'% and 31'%, respectively. Percentages from animal sources are higher among males (68'%) versus females (65'%; p'<'0.001); among those 19–59 years (68'%) versus 60'+'years (65'%), and lower among Non-Hispanic Asian adults (62'%) relative to other race/ethnic groups analyzed. The percentage of total protein contributed by at least one USDA Dietary Pattern food group/subgroup (e.g., Dairy, Grains) differ by all characteristics analyzed except family income. Modest variations in the percentage of total protein from animal and plant foods by demographic characteristics could inform targeted nutrition messaging.