Towards understanding the links between health literacy and physical health.

OBJECTIVE: Low health literacy predicts poor health, but the underpinnings of the associations are yet to be understood. This study tested the associations between health literacy and three objective health outcomes in older people and investigated the extent to which general (not health-related) cognition and earlier life-course factors such as childhood cognitive ability, educational level and occupational class accounted for these associations. METHOD: Participants were 730 community-dwelling older people (350 women; mean age 72.50 years, SD = 0.71). Physical fitness (defined by walk time, lung function, and grip strength), body mass index, and count of natural teeth were used as health outcomes. Rapid Estimate of Adult Literacy in Medicine (REALM), Shortened Test of Functional Health Literacy in Adults (S-TOFHLA), and Newest Vital Sign (NVS) were used to measure health literacy. Age 11 and concurrent general cognitive ability, educational level, and occupational social class were used as covariates. RESULTS: Lower REALM, S-TOFHLA and NVS scores were associated with worse scores on all health outcomes (β = .09 to .17). However, cognitive ability in old age and childhood and educational and occupational levels accounted for the majority of these associations: After adjusting for these covariates, only physical fitness was significantly associated with REALM and S-TOFHLA (β = .06 and .11). CONCLUSIONS: Low health literacy was associated with poorer health largely because it reflected general cognitive ability, educational and/or occupational levels. These variables plays some role in health beyond their association with the reading and numeracy skills captured by common health literacy measures.