Health literacy broadly refers to how people find, understand, and use health information and how organizations make it easier for people to do that. However, researchers continue to debate and define what it means to be nutritionally literate and food literate. While some researchers use nutritional literacy and food literacy synonymously, others distinguish the two and refer to nutrition literacy as going beyond understanding the origin of food, how it is cultivated and processed and its impact on health, to being able to act on nutritional information.
Below are summaries of nutritional and food literacy research and health literacy research with emphases on weight management, interventions for infants and children, food labels, portion sizes, and dietary behaviors.
In a 2021 studyexternal icon, Sanders and colleagues provide the results of a health-literacy intervention for obesity prevention in early childhood. The study followed the children from the age of 2 months through 24 months. At each regularly scheduled well-child visit, parents of children in the intervention group received educational toolkits focused on childhood nutrition, while those in the control group received toolkits focused on injury prevention. The researchers consulted parents from a variety of racial and ethnic backgrounds when developing the toolkits. Physicians caring for the children in both groups received the same number of hours of training in teach-back and plain language. Compared to children in the control group, children in the intervention group experienced less weight gain in the first 18 months of life, but the difference did not persist through age 24 months. The researchers provide explanations as to why the difference did not persist.
Ha, Killian et al.external icon (2020) hypothesized that an intervention designed to enhance skepticism and critical thinking about food commercials would promote healthier food choices among children aged 8-12 years. Over a one-week period, 18 children attended four sessions in which they were exposed to food commercials interspersed with narrative interventions. Another 18 children in the control group were exposed only to the food commercials. All children were encouraged to think aloud during the sessions to share their attitudes about the commercials. The results suggest that the intervention effectively enhanced children’s cognitive skepticism and critical thinking toward commercials. However, the enhanced skepticism towards the commercials did not change the amount of snack food the children consumed.
Privitera et al.external iconexternal icon (2015) conducted a study in which children were asked to choose 4 out of 12 food items in a grocery aisle setting with emo-labels added (happy = healthy; sad = not healthy) and again without emo-labels. Children made overall healthier food choices when emo-labels were present, even when they knew about the unhealthy options available. Emo-labels may not only promote healthier food choices for children, but researchers contend that they may also be a good tool to help increase health literacy at an early age and potentially help reduce rates of childhood obesity.
A preschool program in Australia designed to increase children’s food literacy and encourage children to enjoy vegetables shows that food literacy begins at an early age. The curriculum consists of a one or two hour weekly session taught by dieticians, preschool staff, and volunteers. Whiteley & Matwiejczykexternal icon (2015) found that after the program, over 70% of children asked for and ate more vegetables and parents and preschool staff also reported that children were more knowledgeable about vegetables and had improved food literacy.
A 2015 studyexternal icon used eye-tracking glasses to measure adults’ visual attention to the nutritional information of food products during a food selection task. Front labels used a familiar red, yellow, and green sign and there was a sign with explanatory information near the product. Back labels were the usual nutrition label. Nutrition labels located on the front of products were more likely to be viewed by participants than those located on the back, suggesting that consumers may be more willing to read the shortened and simplified labels.
A 2014 studyexternal icon finds that young adults with poor health literacy are not likely to use food labels to select food products and are more likely to report an unhealthy diet. People with higher self-efficacy use food labels more often. When people use the information on food labels regularly, they tend to have better dietary choices and have better health outcomes. Another studyexternal icon also notes a correlation between poor food label comprehension and low literacy and numeracy skills.
Sinclair & Hammondexternal icon (2013) investigated how well adults could understand nutritional information on food labels. The researchers found that although people self-report high levels of understanding, their actual level of understanding is much lower. Understanding was lowest among people with lower incomes and less education. People with higher education and higher income and White people were more likely to correctly calculate the percentage of daily calories a serving size of a food product would have based on a diet of 2,500 calories per day.
A 2012 studypdf iconexternal icon examined the health literacy and nutrition behaviors of a sample of adults enrolled in the Supplemental Nutritional Assistance Program (SNAP). Race and parental status were found to be significant predictors of health literacy. Using the Newest Vital Sign (NVS) as their health literacy measurement tool, the researchers found that 37% of participants had adequate health literacy. Less than half of the participants reported using nutrition labels when purchasing food. Questions that required numeracy skills were the most challenging for participants.
Chaudry and colleaguesexternal icon (2011) asked people with low literacy and numeracy skills to test digital apps that estimate portion sizes and track food intake. The researchers found that the participants could accurately estimate portion sizes using apps designed for liquids and shapeless foods, but participants had difficulty with apps designed for solid foods. For snacks, participants preferred hand gestures such as the shape of a fist to estimate portion size. The researchers defined snacks as foods that are typically eaten a little at a time and not present on a plate at once, such as pretzels,
A study by Huizinga et al.external iconexternal icon (2009) found that although 91% of study participants reported completing high school, only 65% of them were accurate when asked to serve a single serving of food. Participants who overestimated how much food constitutes a single serving were much more likely to have low literacy and numeracy skills than adults who provided accurate estimates.