The Institute of Medicine defines health literacy as the degree to which a person is able to obtain, understand, and process basic health information and services, so that s/he can make appropriate decisions about his/her health.
Low levels of health literacy among older adults are associated with poorer self-care, particularly of long term conditions, higher than average use of emergency care services, low levels of preventive care, and an overall increased risk of death.
The most important factor governing a decline in health literacy in later years is thought to be dwindling cognitive abilities as a result of ageing, which gradually dulls the brain functions involved in active learning and vocabulary.
The researchers wanted to find out if regular internet use and engaging in civic, leisure, and cultural activities might help to maintain health literacy skills, irrespective of age related cognitive decline.
They therefore assessed the health literacy skills of almost 4500 adults aged 52 and older, all of whom were taking part in the English Longitudinal Study of Ageing (ELSA) between 2004 and 2011.
ELSA is a long term study, which began in 2002, involving a representative and random sample of the population in England aged 50 and older.
Information on internet use and engagement in civic, leisure, and cultural activities was collected every two years. Health literacy was assessed in 2004-5 and again in 2010-11, using a health-related reading comprehension test.
At the start of the study, around three out of four people (73%) had adequate health literacy. After six years, health literacy scores fell by one or more points in around a fifth (19%) of people, regardless of their initial score, while a similar proportion had improved by one or more points.
There was a link between age and declining health literacy, and being non-white, having relatively low wealth, few educational qualifications, and difficulties carrying out routine activities of daily living.
Poorer memory and executive function scores at the start of the study were also linked to greater health literacy decline over the subsequent six years.
Around 40% of the entire sample said they never used the internet or email, while one in three (32%) said they did so regularly. Similar proportions said they had consistently engaged in civic (35%) and/or leisure (31%) activities over the six year follow-up period.
Almost four out of 10 (39%) said they had regularly engaged in cultural activities, such as going to the cinema, theatre, galleries, concerts or the opera, during this time.
Across all time points, internet use and engagement in civic, leisure, or cultural activities were lower among those whose health literacy declined.
After taking account of influential factors, only the links between regular internet use and engaging in cultural activities remained statistically significant.
But each factor appeared to exert an additive effect, and a combination of all four seemed to afford the best protection against health literacy decline, a finding that was independent of any tailing off in cognitive function.
This is an observational study so no definitive conclusions can be drawn about cause and effect.
But the researchers conclude: "Internet use and engagement in various social activities, in particular cultural activities, appear to help older adults maintain the literacy skills required to self-manage health."
They add: "The results indicate that health literacy skills are fluid over time, that loss of literacy skills during ageing is not inevitable, and that technological and social factors should be understood as influences on literacy skills."