February 2012

Nutrition and Health Literacy: A Systematic Review to Inform Nutrition Research and Practice.

Elena T. Carbone, DrPH, RD, LDN; Jamie M. Zoellner, PhD, RD

Health literacy is defined by the authors of this study as "the degree to which individuals obtain, process, and understand basic health information and services to make informed health decisions." Although considered to be a relatively new field of study, health literacy research has grown over the past decade. The purpose of this study was to systematically review health literacy research articles and summarize those that pertain to nutrition and dietetics in order to raise awareness among dietitians of the importance of health literacy in practice and research.

The researchers used 2 methods to identify articles: database literature searches and reviewing references of articles that had been selected. They originally identified 892 citations as being of interest. Of these, 101 remained after eliminating those that did not have abstracts, were not relevent, and weren't written in English. Further elimination brought the sample size down to 33 articles that fell into 3 broad categories: measurement development (4 studies), nutrition-related health literacy studies (13 studies), and nutrition-related readability studies (16 studies).

Currently, no comprehensive measure of health literacy with a focus on nutrition exists that takes into account reading, writing, speaking, listening, use of numbers, and conceptual knowledge. The Newest Vital Sign is a brief screening tool that presents a nutrition label and asks questions to assess participants' reasoning, reading ability, and numeracy skills. The Nutrition Label Survey is another survey designed to assess comprehension of food labels. The Nutritional Literacy Scale is a 28-item reading comprehension assessment tool used to determine understanding of nutrition information. The Cardiovascular Dietary Education System is a test designed to measure literacy skills of African Americans with high cholesterol or hypertension.

Of the nutrition-related health literacy studies identified, 6 were experimental and 7 were non-experimental. Significant findings were that health literacy skills correlate with accuracy of estimating portion sizes and seeking out and trusting in nutrition information sources. Additional findings indicate that participants in SNAP and EFNEP programs may have compromised health literacy status and that years of education is not an appropriate determinent of health literacy.

Readability of education materials is a concern because most adults read at an 8th grade level, with 20% reading at or below a 5th grade level, yet many health education materials are written at a 9th grade level or above. Examples of readability assessment tools identified by this study are the Flesch Reading Ease Formula, the Raygor Estimate Graph, and the Simplified Measure of Gobbledygook (SMOG). Significant findings showed that the reading level of most print- and Internet-based nutrition information is too difficult for many people to comprehend.

The authors of this study contend that poor health literacy affects all levels of the healthcare process and can perpetuate chronic illness. Four main gaps in the literature that the researchers uncovered are the need to address the full spectrum of health literacy factors, the need for more experimental studies on the effectiveness of health literacy studies, the need to explore how an individual's health literacy impacts nutrition outcomes, and the need to assess long-term effects of health literacy interventions on nutrition outcomes. Dietetics practitioners are urged to become familiar with measurement and assessment tools, conduct further research, participate in health literacy training, and advocate as part of the health care team for the monitoring of health literacy.

Carbone ET, Zoellner JM. Nutrition and health literacy: a systematic review to inform nutrition research and practice. J Acad Nutr Diet. 2012;112:254-265.