Exploring the Readability of Ingredients Lists of Food Labels with Existing Metrics

Healthy diet and dietary behaviors are key components in prevention of chronic disease and management of chronic illness. Nutritional literacy has been associated with dietary behaviors and consumer choice of healthy foods. Nutritional literacy can be measured, for example, by examining consumer food label use, but current research focuses largely on the Nutrition Facts panel of a food product. Ingredients lists are critical for communicating food composition but are relatively unstudied in existing literature. The goal of this work is to measure the readability of ingredients lists on branded food products in the United States using existing metrics. We examined ingredients lists for all 495,646 products listed in the USDA Food Data Central database using four existing readability measures for text written in natural language. Each of these indices approximates the grade level that would be expected to comprehend a text; comparatively, patient consent forms are considered acceptable at an 8^th grade reading level or lower. We report a broad variability for in readability using different metrics: ingredients lists recorded at a 9^th grade reading level or higher to comprehend are found at rates of 16.5% (Automated Reading Index) to 74.9% (Gunning-Fog Index). Ingredients lists recorded at a 10^th grade reading level or higher to comprehend are found at rates of 84.2% (using FRE Index). These results demonstrate the need to further explore how ingredients lists can be measured for readability, both for the purposes of consumer understanding as well as for supporting future nutrition research involving text mining.