Dr Oliver Large
December 25, 2025
Perhaps you’ve already had your flu and COVID vaccines - if so, an excellent start. Vaccination provides targeted protection, but everyday habits also play a key role in keeping your immune system resilient through the colder months.
Well-established evidence
These approaches are strongly supported by clinical research:
Keep vitamin D topped up Low vitamin D levels are linked to increased respiratory infection risk. Most adults benefit from a daily supplement of 10 - 25 µg (400 - 1000 IU) throughout winter.
Eat a balanced, nutrient-rich diet Colourful fruit and vegetables, lean proteins, whole grains, and healthy fats supply the vitamins and minerals immune cells need to function well.
Exercise regularly - but not excessively Moderate exercise (around 150 minutes a week) boosts immune circulation and lowers stress hormones. Rest days matter too.
Prioritise sleep Adults sleeping fewer than six hours per night are far more likely to catch colds. Aim for 7 - 9 hours and a consistent routine.
Manage stress Ongoing stress raises cortisol, which can weaken immune defence. Mindfulness, time outdoors, and regular social contact all help restore balance.
Maintain hygiene and ventilation Handwashing, airing out rooms, and staying home when unwell remain simple but highly effective infection-control measures.
Emerging or developing evidence
These may also support immune resilience, though research is still evolving:
Cold-water exposure A Dutch study found that regular cold water immersion (e.g. finishing your shower cold for 30-90 seconds) may help reduce sick-days and stimulate immune pathways. *** Not suitable for those with heart disease, high blood pressure, or asthma ***
Gut health and fermented foods A diverse gut microbiome supports immune balance. Include fermented foods such as yoghurt, kefir, or sauerkraut, and plenty of fibre from fruit and vegetables.
Stay protected this winter
Vaccines reduce the risk of severe illness and help protect those around you.
222 Healthcare is offering private flu, COVID, and RSV vaccinations to those within licensed age categories, suitable even if not eligible through the NHS.
Please enquire for more information or to book an appointment.