Every winter, the search for the secret to staying well seems to intensify.
Supermarket shelves fill with "immune-boosting" shots, cold water swimming groups grow and social media becomes crowded with tips on how to fend off seasonal bugs.
But with so many remedies promising to keep colds and flu at bay, how much of it actually works and is it even possible to boost your immune system in the first place?
Cold water swimming has surged in popularity, with some enthusiasts convinced it keeps winter illnesses at bay.
Immunologist professor Eleanor Riley tells BBC Radio 4's Inside Health podcast that the post-swim "high" is real, but it's driven by adrenaline and endorphins.
