Health Literacy, Numeracy, and Health Promotion: A Secondary Analysis of the Choosewell 365 Workplace Trial

Abstract

Health literacy and numeracy are linked to obesity and dietary behaviors. This study investigates whether the effect of a workplace behavioral intervention to prevent weight gain and improve diet differed by employee health literacy and numeracy. ChooseWell 365 was an RCT of hospital employees testing a 12-month intervention using nudges and feedback to promote healthier choices, building on existing cafeteria traffic light labels (e.g., green=healthy, red=unhealthy). Health literacy and numeracy were measured with the Newest Vital Sign (range=0-6) and General Numeracy Scale (range=0-3). Mixed-effects linear models examined if intervention effects on cafeteria purchases, diet quality (Healthy Eating Index 2015, range=0-100), and weight change over 24 months differed by higher versus lower health literacy or numeracy. Data were collected in 2016-2020 and analyzed in 2020-2021. In 12 months, 510 participants completed the Newest Vital Sign and General Numerancy Scale; 36.7% had Newest Vital Sign<6 (lower health literacy) and 31.6% had General Numerancy Scale<2 (lower numeracy). Intervention participants increased healthy purchases over 24 months compared with controls in both higher and lower health literacy and numeracy groups. At 12 months, Healthy Eating Index 2015 scores increased in intervention versus control participants with lower health literacy (5.5 points, 95% CI=1.51, 9.54) but not in those with higher health literacy (p-interaction=0.040). BMI did not differ by health literacy or numeracy. A behavioral intervention improved cafeteria food choices of hospital employees of varying health literacy and numeracy levels and improved diet quality among employees with lower health literacy, suggesting this group also improved food choices outside of work.