Hydration and Immune Health: 5 Ways to Stay Resilient in the Heat

As warm weather continues across the UK, many of us are reaching for our water bottles more often – and rightly so. Hydration is essential for energy, focus and body temperature regulation. But what’s less widely known is the role it plays in supporting your immune system.

From nutrient transport to immune cell communication, your body’s natural defences rely heavily on fluid balance. Even mild dehydration can begin to affect immune performance, leaving you more vulnerable to illness and fatigue.

In this article, we’ll share five simple, science-backed ways to support your immune health during hot weather – including how hydration, sleep and targeted nutrients can help you stay well.

1. Stay consistently hydrated

It’s easy to think of hydration as a “when you feel thirsty” habit, but in hot weather that can be too late. Dehydration can build up quickly, especially if you're drinking caffeine or alcohol, travelling or spending time in air-conditioned spaces.

Your blood is around 90% water, and your immune system relies on it to circulate white blood cells, carry nutrients and deliver immune signals throughout the body. Without enough fluid, these processes slow down – and so does your immune response.

Tip: Sip water throughout the day and increase your intake after travel, exercise or time in the sun.

2. Support your lymphatic system

Your lymphatic system is one of your body’s key immune defence networks. It helps circulate infection-fighting white blood cells and removes waste, toxins and abnormal cells.

Lymph fluid is also around 90% water, and its flow depends on proper hydration. When you're dehydrated, this system can become sluggish, reducing your body’s ability to defend itself.

Tip: Gentle movement like walking or stretching also supports lymphatic flow, especially when paired with consistent hydration.

3. Protect your body’s first line of defence

Saliva, tears and mucus make up your mucosal barriers – the immune system’s first line of defence against bacteria and viruses. These fluids contain antimicrobial proteins, including lactoferrin, that help trap and neutralise harmful pathogens before they enter the body.

One study found that dehydration can reduce both salivary flow and antimicrobial activity, which may weaken this natural barrier.¹ Maintaining hydration helps preserve this first line of immune defence – and supporting it with nutrients like lactoferrin may enhance its protective function.

Tip: Keep fluid levels topped up in dry indoor spaces or while flying to maintain your body’s natural protective layer.

4. Add targeted nutrients for immune support

Hydration lays the foundation, but your immune system also needs key nutrients to function well.

• Vitamin C supports white blood cell activity and helps reduce oxidative stress

• Lactoferrin is a natural protein that supports immune balance and gut health

Both are included in IMMUNE SHIELD®, a high-purity supplement designed to help support daily resilience, especially during periods of heat, travel or stress.

Tip: Include immune-supporting nutrients as part of your daily wellness habits, alongside hydration and rest.

5. Don’t overlook sleep

Sleep is essential for immune regulation and repair. Poor sleep can weaken your body’s response to illness and increase inflammation.

Even mild dehydration can affect sleep quality, so drinking water regularly during the day (not just before bed) helps support rest and recovery.

Tip: Aim for 7 to 9 hours of restful sleep. Try a cool shower in the evening, switch off devices early and create a calm bedtime routine.

Final thought: hydration is essential, but it’s just the start

This summer, your immune system is working hard to protect and support you – especially during heat, travel and busy days. Consistent hydration, targeted nutrients, good sleep and small daily rituals can make a real difference in keeping you well.

Explore IMMUNE SHIELD® here.

References

1. Fortes MB, Diment BC et al. Dehydration decreases saliva antimicrobial proteins important for mucosal immunity. Appl Physiol Nutr Metab. 2012;37(5):850–859

2. Chishaki T, Umeda T et al. Effects of dehydration on immune functions after a judo practice session. Luminescence. 2013;28(2):114–120