How To Make Your Immune System Stronger: Be Ready For Seasonal Change

Published: October 14, 2020

Updated: November 10, 2025

How to make your immune system stronger isn’t usually top of mind, until the first cough or cold of the season hits. Whether it’s spring or fall, you need to get your immune system in shape to avoid some unexpected colds.

At Sunstar, we truly believe in the healing power of our own body. Sometimes we simply need to unlock our body’s innate capacity to protect us rather than interfering with the protection our immune system offers. Indeed, our immune system acts as a filter against external threats, such as viruses, microbes, and other pathogens.

In this article, we’ll explain how seasonal changes influence your immune system and turn science into practical actions, from what to eat and how to sleep to the roles of stress, oral care, and your environment.

The Connection Between Seasonal Change and Immunity

Just like our bodies adapt to warmer or colder weather, our immune system adapts to seasonal changes too. This natural rhythm helps explain why we may feel more vulnerable to colds or flu in certain seasons, and why strengthening everyday habits that support immunity is so important.

Research published in The Journal of Immunology shows that immune markers and responses display seasonal variability, which may help answer the question of why some illnesses are more common at certain times of the year. For example, the study found that signals of inflammation in the blood, the activity of immune messengers (proteins that help the body fight infections like the flu, Borrelia, and Escherichia coli), and even the numbers of certain immune cells change with the seasons [1].

The bottom line is that with every seasonal change, our bodies face new demands and must adapt. Therefore, it is key to keep healthy habits that strengthen your immune system and prevent seasonal illness.

The Foundations of Strengthening Your Immune System

Enhancing your immune function isn’t about finding a magic pill or relying on short-term fixes. It’s about building healthy habits consistently. These natural ways to support immunity work best when combined, creating a strong foundation for lasting health.

Harvard Medical School [2] highlights several key practices to keep your immune system resilient:

• Get adequate sleep.
• Eat a nutrient-rich diet high in fruits and vegetables.
• Stay active with regular exercise.
• Maintain a healthy weight.
• If you drink alcohol, do so in moderation, and avoid smoking.
• Minimize stress.
• Prevent infections by washing hands regularly and cooking meats thoroughly.
• Stay up to date with recommended vaccines, which prepare your immune system to fight infections before they take hold.

In the sections below, we’ll break down a few of these pillars, and also cover oral care, your home environment, smart supplementation, and age-related considerations, with practical steps you can start today.

Immune System, Sleep and Seasonal Changes

Sleep is not only the body’s time to rest but also one of the most important processes for a strong immune system. During sleep, your body produces signaling proteins (called cytokines) that help regulate how the immune system responds to infections and control inflammation. These proteins act as messengers that guide immune cells, making quality sleep essential for a strong defense system [3].

When sleep is cut short, your body produces fewer protective immune signals, making it harder to fight off pathogens [4].

Research shows that adults who regularly sleep fewer than seven hours per night are almost three times more likely to catch a cold compared to those who consistently get eight hours or more [5]. The study also highlights that even small, chronic sleep deficits can meaningfully increase susceptibility to common viral infections.

Beyond short-term vulnerability, chronic inadequate sleep takes a deeper toll on long-term health. Evidence from psychoneuroimmunology research shows that poor sleep contributes to systemic inflammation and disrupts immune function, raising the risk of serious conditions such as cardiovascular disease, certain cancers, and major depression, all of which further weaken the body’s resilience against infections [6].

As seasonal changes also affect our sleep patterns, taking care of your bedtime routine becomes even more important. Therefore, if you want a healthier immune system, good sleep is the place to start. These sleep tips can help keep your immune system strong:

• Keep a regular sleep schedule (go to bed and wake up at the same time daily).
• Limit caffeine and alcohol close to bedtime.
• Reduce screen exposure at night to protect melatonin production.
• Keep your bedroom cool, dark, and quiet.

Additionally, emerging evidence also points to a two-way link between sleep and oral health. Conditions such as obstructive sleep apnea, dry mouth, and teeth grinding (bruxism) can disturb sleep quality and contribute to fragmented rest (while poor sleep itself may worsen these oral issues). Addressing these problems, for example by managing oral dryness, using protective devices for bruxism, and treating sleep-disordered breathing can support both better sleep and oral well-being.

Stress and the Immune System

Stress and immunity are closely linked: when one suffers, so does the other. In the short term, stress can actually be useful, triggering a “fight-or-flight” response that briefly boosts some immune functions. But when stress becomes chronic, as it often does in modern life, the effect reverses. Long-term stress weakens both the activity of immune cells and the production of antibodies. Moreover, physical vulnerability related to age or disease increases susceptibility to immune changes during stress [7].

This is why reducing stress and taking care of your mental health is so important. Slowing down, resting, and giving yourself space to recover are not luxuries; they are part of maintaining strong immunity.

Take action today with these natural ways to reduce stress and support immunity:

• Mindfulness and meditation help lower cortisol and calm the nervous system.
• Physical activities such as walking or yoga help release tension and improve mood.
• Deep breathing practices activate the parasympathetic nervous system (the body’s natural “rest and recover” system), countering stress.
• Social connection with friends or family provides emotional support and strengthens resilience.

The Link between Exercise and the Immune System

Exercise is one of the most reliable natural ways to support the immune system. The relationship between physical activity and illness risk is often described by the J-curve model [8]:

• Low activity (sedentary lifestyle): Little or no regular movement, such as sitting most of the day, is linked to a higher risk of illness.
• Moderate activity: Regular, moderate-intensity exercise reduces this risk. For example, studies show that people who walk at least five days a week have about 43% fewer days with upper respiratory tract infections (URTIs) compared to those who are inactive.
• High activity: On the other end of the curve, prolonged and very intense training, particularly in elite athletes, can temporarily suppress immunity. Epidemiological studies show that 2% to 18% of elite athletes experience illness during major competitions, most often respiratory infections.

The takeaway? Your immune system thrives on balance. Support it with these exercise habits:

• Aim for moderate-intensity exercise (like swimming or brisk walking) most days of the week.
• Stick to a regular, balanced routine. Consistency and moderation are key to keeping your immune system strong.
• Be mindful with prolonged or high-intensity training (such as marathon training). As the J-curve shows, benefits peak at moderate levels and may decline with extreme workloads.

Supplements for Immune Support

A balanced diet should always come first, but supplements can sometimes help fill gaps when lifestyle (such as busy schedules, frequent travel, or dietary restrictions) or environment (like limited sun exposure, high stress levels, or pollution) make it difficult to get enough nutrients.

According to the National Institutes of Health (NIH), several dietary supplements have been studied for their role in immune function and protection against infections [9]:

• Vitamin C: plays an important role in immune defense, and regular supplementation may slightly reduce the duration of colds.
• Vitamin D: helps regulate immune responses, with evidence suggesting it may reduce the risk of respiratory infections in people who are deficient or have limited sun exposure.
• Zinc: supports normal immune cell function, and lozenges (small, medicated tablets that dissolve slowly in the mouth) taken soon after cold symptoms start may help shorten their duration.
• Echinacea and Elderberry: these medicinal herbs have been investigated for respiratory infections. Some studies suggest they may help reduce symptom severity or duration, but results are mixed and depend on the type and preparation.

It’s important to note that more is not always better. Taking high doses of vitamins or minerals can be harmful. Supplements should be seen as a complement, not a replacement, for a nutrient-rich diet and healthy lifestyle. If you’re considering them, it’s best to consult a healthcare provider to determine what’s right for you.

The Oral Health Connection

Sunstar’s “6 Things You Didn’t Know About Your Oral Health” highlights that your gums do more than just support your teeth, they help shield your body from infections. Gum disease has been linked to systemic conditions such as diabetes, heart disease, and stroke.

In 2024, a team of international periodontal researchers published a key paper arguing that periodontitis (a chronic inflammatory disease affecting the tissues that support the teeth) should be recognized as a systemic disease in its own right, not just a local condition in the mouth. The authors explained that periodontitis is closely linked with other chronic health problems such as heart disease, diabetes, respiratory conditions, and rheumatoid arthritis [10].

This is because inflammation that begins in the periodontal tissues can influence the body’s overall immune response, creating a pro-inflammatory state (when the body remains in an ongoing state of inflammation) and a pro-thrombotic state (when the blood is more prone to clotting) that extend beyond the oral cavity. The paper calls for a new way of looking at periodontitis — as part of the body’s broader network of chronic diseases — and encourages dental and medical professionals to work together to support patients’ overall health [10].

By keeping your mouth clean and healthy, you can lower this source of inflammation and help your immune system work more efficiently.

Here are some recommendations by the European Federation of Periodontology (EFP) [11]:

• Brush at least twice daily for at least two minutes using a manual or electric toothbrush.
• Clean between teeth at least once a day, preferably before brushing; use interdental brushes, or floss if gaps are too small. More on how to floss for better health.
• Have regular professional check-ups at least once a year for early detection of gingivitis or periodontitis.
• Consider antiseptic mouthwashes as a short-term aid, not replacement, to mechanical cleaning.
• Address risk factors like smoking, high sugar intake, and poor diet that increase the risk of gum disease.

Sunstar’s GUM® Oral Care products are specifically designed to help maintain oral hygiene making them a practical tool for supporting both oral and overall health.

Your Environment Shapes Immunity

Your environment has a constant influence on your health, with your immune system especially sensitive to the air you breathe and the spaces you live in.

Research shows that exposure to air pollution weakens immune defenses, increases the risk of respiratory infections, and worsens chronic diseases such as asthma, diabetes, and cardiovascular conditions [12]. Polluted air particles can also trigger oxidative stress and chronic inflammation in the lungs, forcing your immune system into overdrive and leaving fewer resources to fight new infections.

Indoor air quality matters too. Since many people spend up to 90% of their time indoors, poor ventilation, mold, dust, and smoke can significantly strain your immune defenses. High concentrations of indoor pollutants may also worsen allergies [13], indirectly affecting immunity.

Remarkably, surroundings also influence stress levels and mental health. Research on Shinrin-yoku, or “forest bathing” (a Japanese practice of spending mindful time in natural green spaces), has been shown to lower cortisol, decrease stress hormones, improve mood, and increase natural killer cell activity, a type of white blood cell that help defend against infections [14]. Even short walks outdoors or keeping plants at home can provide measurable benefits to your body’s natural defense system.

Building on Sunstar’s “How to Reduce Allergens at Home” and broader scientific evidence, here are a few ways to support immunity through your surroundings:

• Improve indoor air quality with air purifiers, especially if you live in polluted cities or share your home with allergy triggers like dust mites and pets.
• Vacuum weekly to reduce dust mites and allergens from carpets and upholstery.
• Wash bedding and pillowcases in hot water at least once a week and consider allergen-proof covers to minimize dust mite exposure.
• Ventilate daily to reduce the buildup of indoor toxins and mold.
• Avoid secondhand smoke and limit chemical cleaners.
• Control indoor humidity (ideally 30–50%) to reduce dust mite growth and to keep nasal passages from drying out.
• Seek out green spaces (or practice shinrin-yoku, “forest bathing”) for daily stress relief and immune support.

Immune System and Age

As we grow older, our immune system naturally undergoes changes, a process known as immunosenescence. This means that the production of new immune cells slows down, existing cells respond less effectively, and inflammation tends to increase [15]. Together, these changes make older adults more vulnerable to infections such as influenza, and to reduced vaccine effectiveness [16].

The good news is that a weaker immune system isn't inevitable. While it’s true that our defenses naturally change with age, lifestyle choices play a significant role in how resilient immunity remains. Here are a few practical steps older adults can take to strengthen their immune defenses:

• Engage in regular endurance exercise [17].
• Follow dietary habits that have a positive effect on immune aging, including fruits, vegetables and healthy fats [18].
• Stay up to date with vaccines (research notes that regular physical activity can improve antibody responses to influenza vaccinations) [17].

With consistent healthy habits, older adults can maintain more resilient immunity even in later years.

Key Takeaways for Stronger Immunity

As we have learned, the question of how to make your immune system stronger doesn’t have a single answer, it’s about building consistent, healthy habits that work together. Adopting a comprehensive approach that includes a balanced diet, exercise, stress management, and regular health check-ups will improve your immune defenses.

The goal is to create a balanced lifestyle that strengthens your immune system year-round. Sunstar’s healthy habit resources provide further practical tips to integrate such practices into everyday life. Taking small, consistent steps today can help you stay resilient and well in every season

A Holistic Approach: Sunstar’s Commitment to Improving Quality of Life

At Sunstar, we believe that true well-being comes from recognizing the interconnectedness of oral health, nutrition, environment, and overall wellness. The immune system reflects this balance; it thrives when every part of our daily life supports it.

This purpose is what drives our solutions, ensuring we support health from multiple angles.

• GUM® Oral Care: maintaining oral health as a foundation for stronger immunity and reduced inflammation.
• Health Foods & Wellness: supporting nutritional balance and digestive health, key to immune resilience.
• Air Quality Products: helping create cleaner, safer indoor environments that reduce respiratory stress.

Through global initiatives, educational content, and research partnerships, Sunstar continues to promote healthier habits and enhance quality of life. Explore more about Sunstar’s businesses and purpose.

Bibliography

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