Imagine receiving a blood pressure monitor without understanding the readings. A medicine without clear instructions. Or advice to “live more healthily” without knowing where to begin.
These examples raise a question that should sit at the centre of prevention: what does someone need to turn health information into a decision they can use?
Every year, on International Literacy Day celebrated the world over on 8 September, is an opportunity to reinforce health literacy as the operating system of self-care: the capability that helps people interpret information, judge its relevance and decide what to do next.
What is health literacy?
WHO describes health literacy as the ability to find, understand, critically assess and use health information and services. It also recognises that these abilities depend on how organisations communicate and what resources people can access. Health literacy therefore involves both individual capability and the conditions in which people make decisions.
The operating system metaphor helps explain why this matters. We can think of self-care practices – taking medicines, preparing food, being physically active or monitoring symptoms -as applications. Health literacy helps connect those activities to understanding: Why am I doing this? What should I expect? How do I know whether it is helping? When should I seek support?
WHO also explicitly identifies health literacy as a foundation for people’s active participation in their own health. Its account of self-care includes everyday health practices and the use of medicines, devices and tests, within an environment that provides appropriate support and access to professional care.
This has an important implication for how we judge successful self-care. We should indeed value someone recognising their limits and asking for help just as much as their ability to manage independently. A useful question for any self-care intervention is whether people understand both what they can do themselves and when they need someone else.
Consider a hypothetical heatwave. A person might understand the advice to keep their home cool yet have little control over an overheated rented flat. They might know they should reduce exertion but work outdoors. They might recognise concerning symptoms yet be uncertain where to seek advice. We should distinguish these problems. Understanding, practical opportunity and access to support each deserve attention. A leaflet cannot change a tenancy agreement or a working condition
Delimiting self-care
That is also where the operating system metaphor reaches its limit. People need resources, relationships and services alongside knowledge. Any prevention strategy built around self-care should ask what makes the recommended action feasible.
There is a corresponding responsibility for organisations. WHO emphasises that health literacy is shaped by social conditions and that information providers should make trustworthy information understandable and actionable.
For the Prevention Lab, I would translate this into a practical design principle: every recommendation should come with a usable route to action. “Be more active” should open a conversation about an achievable starting point. A monitoring device should come with an explanation of its readings and a clear route to advice. A digital service should make it easy to find help when its instructions are unclear. We should also make room for critical judgement. When someone encounters a compelling health claim, useful questions include: Who produced it? What evidence supports it? What are they selling? What remains uncertain? Does this apply to my circumstances?
It is arguable that asking these questions is itself a form of self-care and our evaluation methods should reflect that ambition. Alongside counting views, downloads or leaflets distributed, we should examine whether people can explain the next step, assess a claim, use a tool appropriately and obtain support. We should ask whose needs the intervention meets and who still faces barriers.
Evey year, International Literacy Day offers an opportunity to put these questions into the prevention agenda. The proposal is simple: treat health literacy as a core requirement whenever we ask people to take an active role in their health. And given that health literacy is the operating system of self-care, building it belongs in the design of every self-care intervention.