Diet quality and food intakes among U.S. adults by level of animal protein intake, What We Eat In America, NHANES 2015-2018

Authors: Hoy, M Katherine; Murayi, Theophile; Moshfegh, Alanna

Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2022
Publication Date: 3/17/2022
Citation: Hoy, M.K., Murayi, T., Moshfegh, A.J. 2022. Diet quality and food intakes among U.S. adults by level of animal protein intake, What We Eat In America, NHANES 2015-2018. Current Developments in Nutrition. https://doi.org/10.1093/cdn/nzac035.
DOI: https://doi.org/10.1093/cdn/nzac035

Interpretive Summary: Dietary patterns associated with lower risk of disease have consistently included fruit, vegetables, whole grains, legumes, nuts, fish, lean meat, and poultry. Such dietary patterns are commonly described as plant based. Including good sources of plant-based proteins is a key component of plant-based diets. These foods, including legumes, nuts and seeds, replace protein from animal sources such as high fat and processed meats and dairy, reducing intake of saturated fat and providing fiber and other nutrients. Dietary guidance encourages consuming a variety of protein foods from plant and animal sources. However, some controversy exists regarding the effect replacing animal foods with plant foods on protein and nutrient intake. The purpose of this study was to update previous estimates of contribution of animal and plant foods to protein intake of U.S. adults by level of percent animal protein (AP) intake. Nutrient intake and diet quality are compared among Low-, Mid- and High-AP groups, and foods contributing to protein intake of each group are described. One day of dietary intake data of adults 20 years and older (N=9566) in What We Eat In America (WWEIA), NHANES 2015-2018 were used. Proportions of protein intake from animal and plant sources as well as from the USDA Food Patterns (FP) groups were estimated for each food reported in WWEIA. The proportions of animal and/or plant protein sources in each FNDDS item were applied to the dietary intakes to determine the population intake of protein from animal and plant sources. The WWEIA Food Categories were used to describe contribution of foods to animal and plant protein intake. Diet quality was evaluated using the Healthy Eating Index (HEI-2015). Overall, about two-thirds of protein intake was from animal sources and one-third was from plant sources. Meat, poultry, and dairy foods were the highest contributors to animal protein intake, and grains were the highest contributor to plant protein intake. Among the Low-AP, about 50% of total protein intake came from plant sources, primarily grains followed by nuts and seeds. Legumes and nuts/seeds together contributed about 10% total protein intake of Low-AP. Four of the five top contributors were grain products and grain-based mixed dishes. Among the High-AP, about 80% of total protein intake was from animal sources, primarily poultry, red meat, fish, and eggs. About 65% of total protein among Mid-AP was from animal sources, including poultry and grain-based dishes. Diet quality score was significantly higher among Low-AP compared to Mid- and High-AP due to better intake of whole grains, legumes, nuts and seeds, and fatty acids. However, their score for protein foods and refined grains were lower compared to Mid- and High-AP and decreased their diet quality. Nutrient intakes of the three groups reflected the sources of protein intake. Good sources of plant protein including legumes, nuts and seeds, and soy products are not consumed frequently by adults in the U.S. The benefits of including good sources of plant-based protein foods needs to be more actively marketed to the population.

Technical Abstract: Dietary patterns associated with lower risk of disease have consistently included fruit, vegetables, whole grains, legumes, nuts, fish, lean meat, and poultry. Such dietary patterns are commonly described as plant based. Including good sources of plant-based proteins is a key component of plant-based diets. These foods, including legumes, nuts and seeds, replace protein from animal sources such as high fat and processed meats and dairy, reducing intake of saturated fat and providing fiber and other nutrients. Dietary guidance encourages consuming a variety of protein foods from plant and animal sources. However, some controversy exists regarding the effect replacing animal foods with plant foods on protein and nutrient intake. The purpose of this study is to update previous estimates of the contribution of animal and plant foods to protein intake of U.S. adults by tertile of animal:plant protein (AP) intake. The database used had proportions estimated from animal and plant sources as well as from USDA Food Patterns (FP) groups, including all mixed dishes. Nutrient intake and diet quality are compared by tertile of AP protein (Low-, Mid-, High-AP), and foods contributing to protein intake are described. One day of dietary intake data of adults 20 years and older (N=9566) in What We Eat In America (WWEIA), NHANES 2015-2018 were used. Proportions of protein intake from animal and plant sources as well as from the USDA Food Patterns (FP) groups were estimated for each food in the Food and Nutrient Database for Dietary Studies (FNDDS) 2015-2018. Single ingredient foods such as chicken or beans were classified as 100% animal or plant, respectively, and then further classified as poultry and legumes, respectively. Proportions from multi-ingredient foods were estimated from the amounts of animal and plant food ingredients in each item. If ingredients were not specified, the proportions from a similar food were applied or a recipe was created using foods in FNDDS. For restaurant foods, information from the company’s website was used. The proportions of animal and/or plant protein sources in each FNDDS item were applied to the dietary intakes to determine the population intake of protein from animal and plant sources. The WWEIA Food Categories were used to describe contribution of foods to animal and plant protein intake. Diet quality was evaluated using the Healthy Eating Index (HEI-2015). Nutrient intake, and total HEI and component scores of the three groups were compared using t-tests in a regression model that adjusted for sex, age, income, race/ethnicity, weight and smoking. Overall, about two-thirds of protein intake was from animal sources and one-third was from plant sources. Meat, poultry, and dairy foods were the highest contributors to animal protein intake, and grains were the highest contributor to plant protein intake among the population. Among the Low-AP, about 50% of total protein intake came from plant sources, primarily grains followed by nuts and seeds. Legumes and nuts/seeds together contributed about 10% total protein intake of Low-AP. Four of the five top contributors were grain products and grain-based mixed dishes. Among the High-AP, about 80% of total protein intake was from animal sources, primarily poultry, red meat, fish and eggs. About 65% of total protein among Mid-AP was from animal sources, including poultry and grain-based dishes. Total HEI-2015 score was significantly higher (P<0.001) among Low-AP compared to Mid- and High-AP due to significantly better intake of whole grains, legumes, nuts and seeds, and fatty acids (P<0.001). However, their score for protein foods and refined grains were lower (P<0.001) compared to Mid- and High-AP and decreased their diet quality. Nutrient intakes of the three groups reflected the sources of protein intake. Good sources of plant protein i