How Does Health Literacy Modify Indicators of Health Behaviour and of Health? A Longitudinal Study with Trainees in North Germany †

Background: Health literacy (HL) is a resource that can help individuals to achieve more control over their health and over factors that influence health. In the present follow-up study, we have investigated the extent to which HL in trainees changes over time and whether or to what extent HL influences health behaviour and health. Methods: In 2017, we performed a baseline survey (T0) of trainees from six different branches, who were contacted through vocational colleges in four northern federal states in Germany. The survey was repeated at the midpoint of their training in 2019 (T1). Demographic data were surveyed, together with information on HL (HLS-EU-Q16), health behaviour and on health status (psychological well-being, subjective health status). Multivariate regression analyses were performed in SPSS 26. Results: Three hundred and ninety-one (391) data sets were evaluated, with a follow-up rate of 27%; 79% of the trainees were female. The mean age was 21.2 years. Over all subjects, the mean HL increased over time ([Formula: see text] (SD): 11.9 (2.9) to 12.2 (2.9), p = 0.070). This increase was only statistically significant for the health service trainees ([Formula: see text] (SD): 12.1 (2.8) to 12.5 (2.9), p = 0.019). Relative to persons with adequate HL, the odds ratio over time for impaired psychological well-being was increased by 230% in persons with inadequate HL (OR: 3.3, 95% CI: 1.70–6.32, p < 0.001). For persons with problematical HL, the corresponding increase in odds ratio was 110% (OR: 2.1, 95% CI: 1.30–3.38, p = 0.002). Relative to persons with adequate HL, trainees with inadequate HL exhibited a significant increase in odds ratio of 2.8 over time for poor or less good subjective health status (OR: 2.8, 95% CI: 1.23–6.33, p = 0.014). Conclusions: We observed a positive longitudinal association between HL and health. A significant increase in HL was observed in trainees in the health service. Thus the study shows that the concept of HL may provide a potential preventive approach for trainees.