The health information gap: the mismatch between population health literacy and the complexity of health information, an observational study. Rowlands G, Protheroe J, Winkley J, Richardson M, Seed PT, Rudd, RE. British Journal of General Practice 

Low health literacy is associated with poorer health and higher mortality. Complex health materials are a barrier to health. This observational study assesses the literacy and numeracy skills required to understand commonly used English health information materials, and to describe population skills in relation to these.