Five key supplements for winter to support health and immunity
Articles
The winter season brings specific challenges for the human body. Shorter days, a lack of sunlight, cold weather, and a higher incidence of respiratory illnesses place high demands on our immunity, energy, and mental well-being. This article covers both sides of the problem: why winter is harder on the airways and the immune system, and which dietary supplements are worth including in your everyday routine to support the body's resilience through the coldest months.
What will you learn in this article?
- Why the respiratory tract is more vulnerable in winter
- Prevention: how to strengthen the immune system naturally
- Mucosal immunity: the body's first line of defence
- Vitamin D: sunshine in a tablet
- Vitamin C and natural acerola
- Omega-3 fatty acids
- Zinc
- A high-quality multivitamin
- B-complex and supportive herbs
- Practical care for the respiratory tract
- What to do when you get sick
- Supplementation as part of a holistic approach
- Key takeaways
Why the respiratory tract is more vulnerable in winter
Cold winter air places a significant strain on the respiratory system. Low temperatures cause the airways to constrict and increase mucus production, which worsens airflow and makes it easier for infectious particles to settle.
The combination of spending time indoors, dry air from heating, and a lack of sunlight weakens the natural protective mechanisms of the mucous membranes. Add to that lower levels of vitamin D and more frequent stress, and together they create an ideal environment for viruses and bacteria.
Prevention: how to strengthen the immune system naturally
A healthy, balanced, nutrient-dense diet is the foundation of prevention, and not only for respiratory illnesses. Our immunity is closely linked to the state of the gut microbiome and an adequate intake of key nutrients.
What to prioritize in your diet
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Anti-inflammatory foods – leafy greens, garlic, onions, ginger, berries, nuts, and fish rich in omega-3 fatty acids.
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Fermented foods – kefir, sauerkraut, kimchi, or yogurts with probiotic cultures that support a healthy microbiome.
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Warm, nourishing meals – soups, broths, and stewed vegetables help maintain internal warmth and support proper immune function.
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Enough fluids – herbal teas (elderflower, linden blossom, mallow, thyme, or ginger) help moisturize the airways and support hydration.
On the other hand, excessive intake of sugar, alcohol, coffee, and ultra-processed foods can weaken immunity, promote inflammation, and disrupt gut balance.
Mucosal immunity: the body's first line of defence
Mucosal immunity (the so-called mucosal immune system) is the first and one of the most important defensive lines of our body. It protects us exactly where we are most exposed to contact with the outside environment, on the mucous membranes of the respiratory tract, digestive tract, and the urinary and reproductive systems. This is where viruses, bacteria, fungi, or toxins most often enter the body.
Unlike immune reactions that take place inside the body (for example via white blood cells and antibodies in the blood), mucosal immunity acts on the surface of mucous membranes. The basic protection here is immunoglobulin A (IgA), an antibody that forms a protective film and prevents pathogens from attaching to the mucosa and penetrating tissues.
The mucosa is also densely populated by the microbiome, billions of friendly bacteria that, together with mucosal immunity, form a defensive barrier. These bacteria compete with pathogens for space and nutrients, and also send signals that teach immune cells how to respond properly. When the microbiome is in balance, immunity works optimally. Conversely, when it is disrupted (for example after antibiotics, due to stress, poor nutrition, or lack of sleep), immune defenses weaken significantly.
Mucosal immunity is closely connected to the overall immune system. A large proportion of the body's immune cells sit in tissue associated with the gut, which explains why a healthy gut microbiome is so essential for defense not only of the digestive system but also of the respiratory and urinary systems. If the intestinal mucosa is out of balance, the risk of recurrent infections, food intolerances, or allergies increases.
For optimal mucosal immune function, adequate nutrition, hydration, a healthy microbiome, and recovery are necessary. Key roles are played by vitamins A, D, C, zinc, selenium, and omega-3 fatty acids, which support mucosal renewal and a proper immune response. Foods naturally containing probiotics and prebiotics are also important, as they synergistically help maintain microbial balance.
Vitamin D: sunshine in a tablet
Vitamin D, often referred to as the "sunshine vitamin", is undoubtedly the number one supplement for the winter months.
Why especially in winter? Our body produces vitamin D primarily through synthesis in the skin after exposure to UVB radiation from sunlight. In latitudes such as the Czech Republic, from approximately October to April, the angle of the sun's rays is not sufficient for this synthesis to effectively occur. Stores built up during summer are quickly depleted, and the vast majority of the population enters the winter months with a deficit. It is recommended to take vitamin D in combination with vitamin K2, as both vitamins work synergistically in calcium metabolism.
Key benefits of vitamin D
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Immune support: Vitamin D plays a key role in modulating both innate and adaptive immune responses. It helps activate immune cells (T-lymphocytes) in the fight against pathogens.
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Bone health: It is essential for proper absorption of calcium and phosphorus, helping maintain healthy bones and teeth.
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Mental well-being: Low vitamin D levels are associated with worsened mood and seasonal affective disorder (SAD), which is typical in winter.
What the evidence says about vitamin D and respiratory infections
The largest analysis to date pooled individual data from 25 randomised controlled trials covering 11,321 participants. Vitamin D supplementation reduced the odds of having at least one acute respiratory tract infection, with an adjusted odds ratio of 0.88. The effect depended heavily on how it was taken: daily or weekly dosing gave an odds ratio of 0.81, while large intermittent bolus doses showed no significant benefit at all (0.97). The strongest effect was in people who started out most deficient, below 25 nmol/L, where daily or weekly dosing gave an odds ratio of 0.75. [1]
The practical message is that steady daily supplementation through the winter does more than occasional megadoses, and that the people who benefit most are the ones who were short of vitamin D to begin with.
How much vitamin D to take in winter
For adults during the winter months (October to April), the preventive dose usually ranges between 1000 to 2000 IU (International Units) daily. For people with a confirmed deficiency, overweight individuals, or older adults, higher doses may be needed and should be determined based on blood test results.
As a reference point for interpreting those results, serum 25-hydroxyvitamin D below 30 nmol/L is considered deficient, 30 to 50 nmol/L inadequate, and 50 nmol/L or above adequate for bone and overall health. The Food and Nutrition Board advises against routinely exceeding roughly 125 to 150 nmol/L, as potential adverse effects have been linked to levels above that range. [2]
Vitamin C and natural acerola
Vitamin C is a powerful antioxidant and one of the best-known vitamins for supporting the body's defenses. For prevention, it is best to choose natural vitamin C, for example in the form of acerola. Trime Acerola is a whole-food ingredient in its natural form, gently processed only by lyophilization (freeze-drying).
Why especially in winter? During periods with a higher incidence of viral infections, our immune system is constantly on alert. While fighting an infection, so-called oxidative stress is created in the body. Vitamin C, as a strong antioxidant, helps neutralize this stress and supports the function of white blood cells. Its consumption also increases sharply during illness.
Benefits of natural vitamin C
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Supporting immunity: Vitamin C contributes to the normal function of the immune system and supports the production and function of white blood cells.
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Reduced fatigue: Contributes to reducing tiredness and exhaustion, a common issue in winter months without sufficient sunlight.
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Why acerola? Unlike synthetic ascorbic acid, acerola (tropical cherry) extract contains a complex of additional compounds, especially bioflavonoids. These compounds increase the bioavailability and utilization of vitamin C itself and act synergistically.
It is worth being realistic about what vitamin C does. The recommended intake is 90 mg a day for men and 75 mg for women, and regular, ongoing supplementation shortens colds only modestly, by roughly 8% in adults and 14% in children. Starting vitamin C only once symptoms have already appeared does not appear to change how long a cold lasts or how severe it is. Taking at least 200 mg a day does not reduce how often the general population catches colds, although it does appear to help people under heavy physical exertion, people exposed to cold, and those with marginal vitamin C status. The tolerable upper intake level for adults is 2000 mg a day. [3] Regular intake through the season is therefore more useful than reaching for a large dose once you already feel unwell.
Omega-3 fatty acids
Omega-3 fatty acids (especially EPA and DHA) are essential fats that our body can produce only to a very limited extent, so it is a good idea to ensure adequate intake through diet and high-quality supplements.
Why especially in winter? Winter is not only a burden for immunity, but also for our mental well-being and skin.
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Mood: Omega-3s (especially EPA) are key for proper brain function and mood regulation. They may play a positive role in preventing and alleviating symptoms of seasonal affective disorder (SAD).
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Inflammation: They have strong anti-inflammatory effects that benefit overall health, including immune regulation.
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Skin hydration: Dry air from heated indoor spaces severely dries out the skin. Omega-3 fatty acids are a key component of cell membranes throughout the body, including skin cells. They help build and strengthen the skin's natural lipid barrier, supporting barrier integrity and promoting hydration from within. As a result, omega-3s contribute to more resilient, more supple skin that is less prone to dryness, cracking, and itching.
For adults, EFSA advises an intake of 250 mg of EPA and DHA per day, and the FDA considers supplemental intakes of up to 5 g per day of EPA and DHA combined to be safe when used as recommended. [4] A common supportive range through winter is 1000 to 2000 mg of combined EPA and DHA daily. Just like with vitamin D, omega-3 dosing can be adjusted based on measured levels: an Omega-3 Index test gives a picture of your fatty acid profile and helps set the dose to individual needs. If you are unsure which product form to pick, our guide to the forms of omega-3 explains the differences.
Zinc
Zinc is an essential trace element involved in hundreds of enzymatic reactions in the body, many of which are directly linked to immunity.
Why especially in winter? Zinc contributes to the development and activation of immune cells and supports the body's immune response. Zinc is also essential for maintaining the integrity of mucosal barriers, which represent the first line of defense against pathogens. A deficiency can lead to a reduced immune response and a higher susceptibility to infections, which is especially risky during the winter months.
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Acute immune response: Zinc is essential for the development and proper function of immune cells, including T-lymphocytes and NK cells (Natural Killer cells).
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Prevention and duration of colds: Studies show that adequate zinc levels, and starting it early at the first symptoms, may shorten the duration of the common cold.
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Antioxidant protection: Acts as an antioxidant and helps protect cells from damage.
When choosing zinc, opt for well-absorbed forms such as zinc bisglycinate. For better tolerance and to prevent stomach upset, we recommend taking zinc with food. During an acute infection intake can be increased short-term, for three to seven days, up to 40 mg per day, ideally split into several doses. That figure is worth treating as a ceiling rather than a target: 40 mg a day is the tolerable upper intake level for adults, and sustained intakes above it can interfere with copper absorption. [5] In Trime Zinc Chelate, we combine zinc with copper precisely to help maintain the natural balance of these two minerals.
A high-quality multivitamin
In winter, our diet is naturally poorer in fresh, local fruits and vegetables. Adding a high-quality multivitamin can therefore serve as nutritional insurance to help compensate for gaps in the diet.
Why especially in winter?
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Filling micronutrient gaps: Winter is a time when we naturally have less variety of fresh foods. A multivitamin helps ensure the body is not missing basic nutrients needed to maintain health.
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Supporting energy metabolism: Especially B vitamins, which multivitamins contain, are involved in energy metabolism and are key for converting food into energy. This helps fight winter fatigue as well.
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Comprehensive support: Provides a broad spectrum of compounds (for example selenium, zinc, vitamin E) that work together to support the immune system, nervous system, and protect against oxidative stress.
B-complex and supportive herbs
Two more groups are worth a mention, because they come up constantly in winter routines.
B-complex
The B vitamins contribute to the maintenance of normal mucous membranes, and therefore to their proper function, as well as to normal energy-yielding metabolism and the reduction of tiredness. The right amount is usually individual, taking into account diet and the other demands placed on the body. If you already take a full-spectrum multivitamin, a separate B-complex is often unnecessary.
Herbs
Echinacea, elderberry, mallow, thyme, or ginger are traditionally used to increase the body's resilience and are often reported to shorten the duration of illness. They work best as a complement to the nutrients above rather than as a replacement for them.
If symptoms worsen, you develop a fever, or you feel chest pain, we recommend visiting your doctor.
Practical care for the respiratory tract
Preventing respiratory illnesses is not only about nutrition, but also about practical protection of the airways. The immune system works best when the body has enough strength and time to recover.
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Breathe through your nose, not your mouth, because the nasal cavity naturally warms, humidifies, and filters the air.
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When outdoors, protect your mouth and nose with a scarf, so overly cold air does not reach your lungs.
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Keep your home temperature around 18 to 21 °C (especially in the room where you sleep) and maintain adequate humidity, ideally 40 to 60%. Avoid overheating rooms.
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Avoid mold and smoke, which can irritate the airways.
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Inhalation or a steam bath with essential oils (for example eucalyptus or mint) moisturizes the mucosa and helps open the airways.
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Sleep is key – aim for 7 to 9 hours of sleep regularly, which will help keep your immune system stronger.
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Regular movement – even a light walk or breathing exercises that support lung capacity.
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Stress management – meditation, breathing techniques, or relaxation help lower cortisol levels, which can weaken immunity.
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Sauna or alternating hot and cold water supports overall immune resilience.
What to do when you get sick
If you do get sick, give yourself peace and rest, plenty of fluids, and easy-to-digest nourishment. The body needs energy for recovery, not for digesting heavy meals. Broths, high-quality protein, and stewed vegetables are good choices. Avoid smoking and alcohol, which put extra strain on the respiratory tract.
People with chronic lung disease should always consult a doctor in winter if their condition worsens.
Supplementation as part of a holistic approach
It is important to emphasize that dietary supplements do not replace a varied, high-quality diet, enough sleep, and regular movement. They should be understood as a targeted supportive pillar that helps the body better cope with the specific demands of the winter season. Investing in high-quality supplements such as vitamin D, vitamin C, omega-3 fatty acids, and a multivitamin or multimineral complex can significantly contribute to maintaining robust health, supporting energy, and sustaining a good mood even during the coldest months of the year.
Key takeaways
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Winter works against the airways on several fronts: cold air constricts them and thickens mucus, heated indoor air dries the mucous membranes, and vitamin D synthesis stops for months.
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Mucosal immunity is the first line of defence: it depends on healthy mucous membranes, adequate nutrients and a balanced microbiome, which is why gut health and respiratory health are linked.
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With vitamin D, consistency beats size: daily or weekly dosing reduced the odds of acute respiratory infection (odds ratio 0.81), while large intermittent bolus doses showed no significant benefit.
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Vitamin C is for the whole season, not the first sneeze: regular intake shortens colds modestly, while starting it after symptoms appear does not change their course.
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Zinc helps early and has a ceiling: starting at the first symptoms may shorten a cold, but 40 mg a day is the upper limit for adults, not a routine dose.
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Supplements are support, not the foundation: diet, sleep, movement, humidified air and stress management do the heavy lifting; supplements fill the gaps winter creates.
Sources:
[1] Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583. doi: 10.1136/bmj.i6583
https://doi.org/10.1136/bmj.i6583
[2] National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
[3] National Institutes of Health, Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
[4] National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
[5] National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
