With colder temperatures, less sunlight, and increased time spent indoors, our bodies become more susceptible to seasonal illnesses like colds, the flu, and even respiratory issues. As we transition into winter, we must pay extra attention to how we can support and strengthen our immune systems to stay healthy and vibrant.
The immune system plays a vital role in protecting our bodies from infections. It can fend off harmful viruses and bacteria when functioning at its best. However, chilly weather, seasonal stress, and reduced physical activity can weaken our natural defences, leaving us vulnerable to illness. We must adopt healthy habits that nourish our bodies and minds to thrive during winter.
This post will explore proven strategies and natural methods for boosting your immune system as we enter this new season. From nutrition tips to simple lifestyle adjustments, we will cover how to enhance your body's resilience.
Whether you want to ward off the seasonal sniffles or feel more energized as the days are shorter, these tips will help you enjoy winter to the fullest while keeping your health in shape. Let's explore how to stay strong, healthy, and well-prepared as we embrace the beauty of winter.
What is the immune system?
The immune system is a network of cells, tissues, and organs that protects the body from a wide variety of pathogens (viruses, bacteria, parasites), external aggressions (pollutants, radiation), and even internal issues (cancer cells).
The immune system is formed by soluble molecules like proteins, antibodies, and histamine in various body fluids, mainly blood and lymph, distributed among multiple tissues and organs.
Our immune system is our primary natural protection. Therefore, it is essential to keep it strong and healthy. A weak immune system will not detect infected cells and will be unable to eliminate bacteria and viruses promptly. We are prone to infections with a weak immune system.
Conversely, a strong immune system will react quicker and better to external aggressions and microorganisms. We will be healthier, suffer from fewer infections, and recover quicker.
Main immune cells
There are two types of cells in the immune system: lymphocytes and support cells. Lymphocytes are the most important immune cells, divided into three main types: B, T, and NK ( natural killer cells ). Support cells interact with lymphocytes and help them regulate immune responses. They are also divided into different types, such as monocytes, macrophages, and others.
Lymphocytes
B cells: These cells are responsible for producing antibodies.
T cells: These lymphocytes attack and destroy cells infected by viruses or other threats.
NK cells (Natural Killer cells)Â directly attack virus-infected cells and tumour cells.
Support Cells
Monocytes: These cells are precursors of macrophages. They circulate in the blood before migrating to where they are needed, where they transform into macrophages and perform phagocytic functions (the process by which phagocytes, a type of white blood cell, engulf and destroy foreign substances and dead cells).
Macrophages: These are phagocytic cells involved in eliminating pathogens and dead cells.
Neutrophils: Phagocytic cells are essential in the first immune response against bacteria and other pathogens.
Basophils and Eosinophils: Basophils release pro-inflammatory substances, while eosinophils specialize in destroying multicellular parasites.
Reticular cells are part of connective tissue and provide a structural scaffold for other cell types in the lymphoid organs.
Dendritic cells: These cells present antigens to lymphocytes (triggering the generation of antibodies). They are essential for the initiation of adaptive immune responses.
Some of these cells produce cytokines, signalling molecules that tell cells where to go and what to do. Cytokines can direct immune cells toward an infection site so that the cells can fight germs there.
What factors affect our immune system?
Different factors can damage our immune system and slow down our immune response. Some of these factors are:
Stress increases the production of glucocorticoids in our body. Glucocorticoids are cytokines and inhibitors of white cells. Under stress, we produce fewer white cells and can easily catch infections.
Unhealthy diet. Our immune system needs different vitamins and minerals for optimum efficiency. Later in this post, we will examine the essential vitamins and minerals for a strong immune system and where to find them.
Bad Sleeping Habits produce an imbalance in the cortisol/melatonin equilibrium. This causes the body to enter a stress phase, where the immune response becomes slower.
Overweight. Fatty tissue around the organs affects how they work. That also applies to the organs involved in the immune response and producing immunity cells.
Some medications can interact with the production of immunity cells. Corticosteroids and immunosuppressant drugs are examples.
Cold weather. Cold weather affects our body at different levels, including the immune system and how it works.
Nicotine and alcohol affect the effectiveness of phagocytic cells and reduce the life span of macrophages. This slows down the immune response and weakens the immune system.
Pregnancy. During pregnancy, the foetus is a foreign body inside the mother. The baby's body acts as an antigen for the mother's immune system, reducing the immune response. Otherwise, the mother's antibodies would attack the foetus, producing a miscarriage.
Age. As with any other part of the body, the immune system weakens and becomes less effective as we age. This is a natural physiological problem that occurs with age.
Other diseases. Some diseases, such as diabetes and kidney and liver issues, may negatively impact our immune system.
Symptoms of a weak immune system
There are a few symptoms related to a weak immune system. The most important are:
Frequent colds, flu and other infections. On average, adults can suffer from 2-3 colds every winter. They usually last a maximum of a week (with or without medication). A high number of infections and longer recovery times indicate a weak immune system.
Digestive problems. A weak immune system produces digestive issues like frequent diarrhoea, constipation or bloating.
Wounds take longer to heal if the immune system weakens, and there is a higher risk of infections.
Frequent tiredness. It is expected to be tired at the end of the day. However, if you are always tired, your immune system may weaken even after a good sleep.
How does cold weather affect our immune system?
The first body response is the well-known shivering with goosebumps when cold. The body tries to keep the temperature close to the optimal physiological value, around 37 degrees centigrade.
To do that, our body needs to undergo different processes. First, the blood vessels on the skin's surface contract because blood is more necessary around vital organs. Consequently, our skin becomes cold, especially on our hands and feet.
At the same time, the blood's density increases, and the heart needs to work harder to pump the same amount of blood. This can create heart issues. The cold can also affect the joints, skin, and brain.
Low temperature influences how our immune system works. Our immune cells work optimally at physiological temperatures. When we breathe cold air, the temperature in our airways (trachea and bronchi) decreases by a few degrees. The immune system slows down at this slightly lower temperature and does not effectively fight microorganisms.
At the same time, environmental conditions like temperature and humidity are ideal for spreading bacteria and viruses quickly.
It is essential to boost our immune system when we enter autumn & winter.
How can we boost our immune system?
Colds, flu, and COVID-19 are the most common ailments during autumn and winter. As I explained, low temperatures and high humidity slow the immune system response and accelerate the growth of bacteria and viruses
Fortunately, there are a few things we can do to help with this situation:
Eat warm meals. It sounds like an urban myth, but eating soups in winter helps to boost the immune system. Soups contain proteins, fibre, minerals, vitamins, and water. Some of these ingredients favour better digestion. On the other side, the warmth of the soup also helps with digestion.
Include superfoods in your diet. Some foods can boost our immune system. Remember that our immune system needs minerals and vitamins to work optimally. We will discuss which vitamins and minerals these are later.
Drink herbal teas. Herbal teas are a good option for keeping yourself warm and are caffeine-free. Some herbs can also help boost your immune system. We will provide some beneficial tips on herbal teas later in this post.
Sleep at least 8 hours. During sleep, our immune system repairs and strengthens. Ideally, we should sleep 7-8 hours per night.
Practice some physical activity. During exercise, the body eliminates lung viruses and bacteria, which can help prevent respiratory diseases like colds, flu, and COVID-19.
The most essential nutrients for a stronger & healthy immune system
We need an equilibrated diet that includes nutrients from each group (carbohydrates, proteins, fats, etc.). A balanced diet should also consist of micro-nutrients like vitamins and minerals. We need to pay special attention to include in our diet the following:
Omega-3 fatty acids reduce tissue inflammation and boost the immune system. They are found in some fish, such as sardines, salmon, tuna, chia seeds, and walnuts.
Copper and selenium. Selenium influences the activity of the immune system, while copper increases the life span of white cells. These minerals are found in wheat, rice, egg yolks, sunflower seeds, chicken, and cheese.
Zinc. Zinc helps to boost the skin barrier and activate some immune cells. It also protects against oxidative stress, which weakens the immune system.
We can obtain zinc from beef, chicken, turkey, liver, pumpkin seeds and nuts.
Vitamin C. Vitamin C is a vitamin soluble in water that helps to fight microorganisms and protects against oxidative stress. We can obtain vitamin C from some fruits and veggies, like citrus fruits, pineapple, strawberries, papaya, melon, mango, kiwi, broccoli, tomato, etc.
Vitamin E. Vitamin E exerts antioxidant functions on immune cells by protecting them from damage caused by free radicals, which can weaken the immune system and increase susceptibility to disease.
Some foods rich in vitamin E are sunflower seeds, peanuts, almonds, pistachios, mango, olive oil and tomato.
Vitamin A. Vitamin A reinforces the mucosa tissue, mainly in the nose and throat. That protects us against microorganism infections. Vitamin A is found in carrots, sweet potatoes, mangoes, spinach, beetroot, lettuce, and eggs.
Vitamin B. Vitamin B helps the immune cells detect pathogens and favour immune cell growth. Vitamin B's primary sources are meats, eggs, milk products, liver, kidneys, and fish.
Probiotics. Probiotics induce natural body defence growth. Probiotics are mainly found in kefir, milk, and yoghurt.
Iron. It is uncommon to relate iron to the immune system, but it is a key mineral for optimum immune system behaviour. The best sources of iron include dried legumes, dried fruits, eggs (especially yolks), liver, red and lean meat (especially beef), oysters, poultry, dark red meats, salmon, tuna, and whole grains.
Which foods shall we eat?
We should have a diet rich in food from each of the following groups:
Fruit. Blueberries, kiwi, papaya and watermelon are the best food combinations to boost the immune system.
All these fruits are rich in vitamins C, D and K. They also contain antioxidants and potassium. They are essential fruits for a healthy immune system.
Try to include citrus fruit in your diet, as it is a source of vitamin C.
Some fish. The healthiest fish for the immune system are tuna, mackerel, salmon and swordfish. All of them are rich in omega-3 fatty acids, which have antioxidant properties. If you are not allergic, eating seafood like mussels, oysters, and crabs is advisable due to their high zinc content.
Nuts are ideal snacks because they don't provide empty calories. They reduce our appetite while providing vitamin E and minerals like magnesium, potassium, calcium, selenium, copper, and zinc.
Veggies. Surprisingly, red pepper has a higher vitamin C content. You can add it to a wide variety of dishes. Other important veggies to consume are broccoli, spinach, and mushrooms. Pumpkin is rich in vitamin A, carotenes, and vitamins B, C, and E. Pumpkin is ideal for preventing infections and is readily available in the shops during autumn and winter.
Artichokes are rich in minerals like phosphorus, potassium, copper and zinc.
Kefir. Kefir is a product of milk fermentation. It contains many beneficial bacteria responsible for converting lactose into lactic acid. These bacteria act as an immune system shield.
The Best Herbal Teas for Your Immune System
We mentioned that herbal teas can help keep us warm and boost our immune system. But which are the best herbal teas to consume?
Echinacea is the most popular herbal tea for boosting the immune system. It contains molecules that help produce immune cells.
Ginger. Ginger is a root with anti-inflammatory and anti-microbial properties. It is a good option to prevent infections.
Garlic is an antibacterial and antiviral food. Drinking garlic tea helps prevent infections and strengthens the immune system. Due to its taste and smell, it may be advisable to have garlic in tablets rather than in tea.
Elderflower. Elderflowers are rich in antioxidants and vitamin C, essential for the immune system. Elderflower teas are ideal for preventing colds and flu.
Propolis. Propolis is a resin produced by bees. It has antibacterial and anti-inflammatory properties, making it the perfect supplement to prevent infections during autumn.
My two favourite herbal teas for cold seasons are:
Echinacea with elderflower. The combination of both is ideal to increase white cell production.
Lemon, ginger, turmeric, and honey. I drink this tea when I have a sore throat. Lemon is rich in vitamin C, ginger and turmeric are anti-inflammatory, and honey helps to soothe my throat.
As we transition through the winter months, keeping your immune system strong is essential to staying healthy during the colder months. You can effectively boost your body's defences by incorporating simple habits like eating nutrient-rich foods, staying active, managing stress, and getting enough sleep.
Following these practices consistently will help protect you from seasonal illnesses and ensure you enjoy a vibrant, illness-free autumn. Stay healthy, and embrace the season with confidence!
Dr Irene Resa
Bioanalytical Chemist
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