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Why do we tend to catch colds and flu during winter? YHL finds out from the experts

The winter months are notoriously a time when colds and flu strike. But what is it about this time of year that makes us so vulnerable to viruses and bugs? And, importantly, what can we do to protect ourselves from them?

"Firstly, the viruses responsible for these illnesses (such as the influenza virus) thrive in colder temperatures," says Shona Wilkinson, lead nutritionist at ethical supplement and nutrition brand Dr. Vegan ( "The cold and dry air provides the perfect environment for these viruses to linger for longer periods, increasing the chances of transmission. Further, people spend more time indoors trying to keep warm, generally increasing our proximity to each other and increasing the likelihood that we'll pass something over through respiratory droplets.

Additionally, reduced exposure to sunlight over winter often leads to a decrease in our vitamin D levels. Vitamin D plays an essential role in supporting our immune systems, so a deficiency decreases the chances of our body being able to fight off any nasty infections."

Lauren Johnson Reynolds, aka the London Wellness Coach, ( adds: "Research suggests that colder temperatures actually impact how well our body, particularly the nose, is able to protect us from illnesses.

Our noses, particularly the little hairs that line our nostrils (called cilia) act as filters, trapping particles from the air we breathe, preventing them from entering our bodies. Colder weather, even as little as a 5-degree drop, can slow down the movement of the cilia or even stop it altogether, leaving us open to intruders. This is one way that cold temperatures impact the immune defence in the nose alone."

Immune system stressors

"Chronic stress is something that can seriously weaken our immune system," says Shona. "In fact, chronic stress releases hormones that suppress our immune response, meaning we're more likely to catch something. Sleep is another thing that plays an enormous role in helping us fend off illness. The less sleep we get, the less prepared our body is to fend off illness, so it's certainly something we should prioritise if we're looking to stay healthy during the colder months. Perhaps most important is nutrition. Poor nutrition can lead to deficiencies in essential vitamins and minerals such as vitamin D, C, and B12, which reduces our body's chance of fighting off an infection."

Here are some tips to keep colds and flu at bay during the colder months.

Balance your blood sugar

"Of course we can all enjoy a tipple once or twice a week," says Lauren, "but it's important to be aware of the strain that blood sugar imbalance has on our cortisol (stress hormone) levels and overall health. Not just this but both sugar and alcohol can disrupt the delicate balance between good and bad bacteria in the gut. Instead, focus on whole foods with plenty of protein, healthy fats and fibre." Shona adds: "Adequate nutrition, including a balanced diet rich in vitamins and minerals, is essential in supporting a healthy immune system. If you can't get everything you need from your diet, consider taking a daily multivitamin to improve general health or a vitamin D supplement if exposure to sunlight is limited."

Take care of your gut

"Since over 70 per cent of our immune system is in our gut, supporting a healthy microbiome is key to a healthy immune system," says Shona. "There's also a whole host of other benefits to a healthy gut, including improved mood, healthier skin, and better digestion." Lauren adds: "Incorporating fermented foods like kimchi, sauerkraut, live yogurt and kefir into our daily diets gives us a boost of friendly gut bacteria. And eating a wide variety of fruit, vegetables, herbs and spices provides a range of fibre that feeds those gut bugs and strengthens our microbiome overall."

Maintain good hygiene

"Regular handwashing, especially during the winter months, can help prevent the spread of viruses," says Shona. "Proper hand hygiene is crucial after touching surfaces in public places and before eating."

Adopt a regular bedtime routine

"Sleep helps the immune system in the same way that stress-reduction techniques do," says Steph Baker, a registered nutritional therapist and in-house nutritionist consultant for Purolabs ( "It reduces the nervous system's response to set off ‘triggers' for the immune system to respond to, to perceived threats, aka our fight or flight response. If our fight/flight response is chronically triggered, this can exhaust our immune system and have it ‘fighting' non-threats, when it could be dealing with other internal processes that need support. Sleep also helps the body to repair and ‘reset' for the next day. Our circadian rhythm, which is our internal body clock, has a strong mediating influence on the immune system. If our sleep patterns follow natural sleep and waking hours, it positively impacts immunity. Keep a regular bedtime and wake-up time for your body to attune to its circadian rhythm. Remove exposure to blue light devices (iphone/ipad/laptop etc) 60 minutes before bedtime. Blue light blocks melatonin, which is the hormone that signals to us that it's time for bed. Exposure to blue light before sleep will impact sleep quality. Also, ensure that your bedroom is well-ventilated, dark, and cool to provide optimal conditions for a restful sleep."

Get outside in daylight

"Even in the winter months we can benefit from natural light," says Lauren. "The impact this has on our circadian rhythm (our sleep/wake cycle) helps us to get more restful sleep naturally. Not just this but spending time in nature has been shown to support our nervous system, reducing our stress response and therefore improving our immunity."

Go natural

"Herbal remedies like echinacea and elderberry can support the immune system naturally," says Lauren. "Elderberry particularly has been shown in studies to reduce the severity and length of upper respiratory infections in studies. Herbs like oregano, basil, peppermint and rosemary are antiviral and even garlic, ginger and manuka honey can be a useful first defence from winter illnesses."

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