Estimating Animal and Plant Protein Intakes in Diet Assessed by ASA24 and Food Records

AbstractBackground Despite growing interest in the distinct roles of animal protein (AP) and plant protein (PP) in health, commonly used dietary assessment instruments estimate only total protein intake and do not differentiate between protein sources. Objective To develop a protocol to estimate AP and PP intake in diets assessed by the automated self-administered 24-Hour recall (ASA24) and food records. Methods We used data from the Interactive Diet and Activity Tracking Study, including 926 participants (mean age, 63.1 years). Participants completed up to six ASA24s and two 4-day food records (4DFRs) over 12 months. AP and PP were defined as proteins derived from animal- and plant-based foods, respectively. AP and PP were estimated by linking foods reported on ASA24 and 4DFR to the USDA Food and Nutrient Database for Dietary Studies, USDA National Nutrient Database for Standard Reference, MyPyramid Equivalents Database, and Nutrition Data System for Research. The validity of the method was assessed by comparing the original total protein intake to the summed AP and PP estimates. Results A total of 3,171 and 3,652 unique foods were reported on the ASA24s and 4DFRs, respectively. The mean difference between the original total protein values and the sum of AP and PP was negligible for both ASA24 (0.027g/100g food; SD=0.63) and 4DFR (0.019g/100g food; SD=0.69). Approximately 89% of ASA24 and 88% of 4DFR foods had differences within ±0.1g/100g. Based on ASA24, AP accounted for 61% of total protein intake in men and 57% in women. The top sources of AP were red meat (19.3%), poultry (14.0%), and cheese (10.4%). In contrast, PP was mainly from bread (19.6%), nuts and seeds (10.9%), and pasta (7.1%). Conclusions This protocol provides a practical tool for estimating AP and PP intake from ASA24, thereby advancing nutritional epidemiologic research and supporting the development of evidence-based dietary guidelines.