How to support your immune system and mood over winter

Written by Martin Ebner,
Last updated October 2026

Every winter, it seems as though half the people around me start coughing at once. One client cancels, then another, and suddenly every train carriage sounds like a respiratory ward.

You can’t make yourself invincible with an orange, a supplement and a determined expression. You can, however, give your body better conditions to do its job.

I grew up in Edinburgh, so I have limited sympathy when Barcelona describes winter as brutally dark. Even here, though, the days shorten, routines shrink and people spend more time indoors. Movement drops, sleep changes and your mood can follow.

YOUR IMMUNE SYSTEM DOESN’T NEED A PEP TALK

Your immune system isn’t a biceps. You can’t hammer it for six weeks and watch it grow.

It’s a complicated network that needs to respond when required without becoming overactive. That’s why “boosting” it isn’t a particularly useful goal. Supporting normal immune function through adequate nutrition, sleep, movement and recovery is much closer to what we actually want.

No individual food or supplement can stop you catching a cold. Anyone promising otherwise is selling certainty that doesn’t exist.

VITAMIN C MATTERS, BUT IT ISN’T BODY ARMOUR

Vitamin C is essential for normal immune function, collagen production and several other processes your body would rather not perform without it. That doesn’t mean taking a large dose will stop every cold at the door.

The NIH summary of the evidence found that regular vitamin C supplementation doesn’t appear to reduce the risk of catching a cold in the general population. It may shorten a cold slightly, particularly when taken regularly rather than started after symptoms appear.

Fruit and vegetables should do most of the work. Citrus fruit, kiwi, berries, peppers, broccoli and potatoes all contribute. Frozen fruit and veg count too. Your immune system doesn’t award extra points because the broccoli was photographed beautifully before you ate it.

I’ve covered this in more detail in my ultimate guide to vitamin C. If your diet is inconsistent and you want a reliable back-up, Performance Lab Vitamin C provides 250 mg per serving. I’d treat it as a convenient way to fill a gap, not a force field.

DON’T FORGET VITAMIN D

Vitamin D deserves more attention during winter because sunlight is one of our main sources and the shorter days make adequate exposure more difficult in many countries.

The NHS recommends considering 10 micrograms of vitamin D each day during autumn and winter. That’s UK guidance, and individual needs vary according to location, skin tone, sun exposure, diet and existing vitamin D levels.

Living somewhere sunny doesn’t guarantee adequate vitamin D if most of your day is spent indoors. Equally, taking more than you need isn’t automatically better. If you’re concerned about deficiency, testing and proper medical advice beat guessing.

SLEEP IS DOING MORE THAN YOU THINK

Sleep is often the first thing people sacrifice when life gets busy, then they wonder why training feels flat, hunger increases and everything becomes slightly more irritating.

In a controlled viral-exposure study, people sleeping fewer than six hours were around four times more likely to develop a cold than those sleeping more than seven. That doesn’t mean one late night guarantees illness, but consistently poor sleep isn’t helping.

Try to keep your bedtime and waking time reasonably stable, make the room dark and cool, and stop treating your phone as a tiny bedtime television. If you’re already doing the basics and still want some additional support, Performance Lab Sleep combines magnesium, Montmorency tart cherry, L-tryptophan and lemon balm.

A supplement can support a good routine. It can’t rescue one that involves caffeine at dinner and emails in bed.

TRAIN, BUT DON’T TRY TO OUTWORK A VIRUS

Regular exercise supports far more than how you look. A large systematic review and meta-analysis found that habitual physical activity was associated with a lower risk of community-acquired infectious disease, alongside measurable changes in parts of the immune system.

That doesn’t mean you need to train brutally every day. Two or three good strength sessions, some steady cardio and regular walking will cover an enormous amount of ground.

I wouldn’t turn winter into a daily HIIT challenge in the hope of frightening every virus away. Training creates stress as well as adaptation, and recovery still needs somewhere to happen.

If you’re genuinely ill, resting for a few days isn’t laziness or lost discipline. It’s usually the quickest route back to productive training. A workout performed while you feel dreadful rarely becomes the heroic session you imagined.

MOVEMENT STILL COUNTS WHEN IT ISN’T A WORKOUT

A formal workout is useful, but it isn’t the only movement that matters.

Walk to the shops, take the stairs, get outside at lunchtime or add ten minutes of movement between long periods of sitting. These things don’t need gym clothes, a smartwatch or a motivational soundtrack.

Regular movement can help maintain energy, support sleep and prevent winter from turning your entire routine into work, sofa, bed and repeat. It also makes returning to the gym considerably easier than spending three months doing almost nothing.

GET SOME ACTUAL DAYLIGHT

Reduced daylight can affect mood, sleep and the body clock. The NHS guidance on seasonal affective disorder identifies reduced winter daylight as a possible factor and includes regular exercise among the things that may help.

Try to get outside during daylight, ideally earlier in the day or around lunchtime. Even a cloudy outdoor walk gives you considerably more natural light than sitting beside a window.

This isn’t about pretending a walk cures depression. If your mood remains low, begins affecting daily life or returns severely every winter, speak to a qualified healthcare professional. That deserves more than another supplement and an instruction to cheer up.

EAT LIKE YOUR BODY HAS WORK TO DO

Winter nutrition doesn’t require a separate personality. You still need adequate protein, fruit, vegetables, carbohydrates and fats, ideally across meals you genuinely enjoy eating.

Soup counts. Frozen vegetables count. A comforting meal can still contain protein and plants. There’s no prize for eating cold salad in January while wishing it were literally anything else.

Try to make the basics repeatable. Include a decent protein source with your main meals, eat a useful variety of plants across the week and keep enough food in the house to stop every busy evening becoming an emergency delivery.

WHERE SUPPLEMENTS FIT

Supplements are most useful when they fill a real gap or make consistency easier. They’re much less impressive when they become an expensive attempt to compensate for poor sleep, little movement and a diet held together by coffee.

If you’d rather use one combined product than open several bottles, Performance Lab Immune contains vitamin C, vitamin D3, zinc, selenium, glutathione and LC-Plasma. View it as one convenient formula, not protection against every person coughing beside you.

I wouldn’t stack it blindly with a multivitamin, separate vitamin C and additional vitamin D. Check what each product contains and consider what you actually need. More capsules don’t automatically create more protection.

MAKE WINTER EASIER, NOT PERFECT

You don’t need a perfect winter routine. Keep training, keep moving, get outside while there’s daylight, protect your sleep and eat like somebody whose body has work to do.

Supplements can support those habits. They can’t replace them.

If winter has a habit of shrinking your world to work, the sofa and whatever’s in the snack cupboard, Check It Oot is where I write about training, nutrition and health without pretending January requires a complete personality transplant. One email once or twice a month, written by me, straight to your inbox.