Ask Dr Joseph
How can I strengthen my immune system?
Key takeaways
Strengthen and unlock your inner resources
Our immune system is the body’s central line of defense: a finely tuned network of cells, organs and messenger substances that recognizes invaders and fights them in a targeted way. For our defenses to work reliably, they need a healthy foundation: a balanced diet, enough sleep and regular exercise. Botanical companions such as echinacea, elderberry or rose hip also have a firm place in traditional use.
Frequently asked questions about the immune system
- What is the immune system?
- What weakens the immune system?
- How can I tell if my immune system is weakened?
- How can I build up my immune system?
- Which foods support the immune system?
- How does exercise affect the immune system?
- How does sleep affect the immune system?
- What role does the gut (microbiome) play in immune defense?
What is the immune system?
The immune system is our body’s biological shield. It recognizes foreign invaders such as viruses, bacteria or fungi and protects us from infections. At the same time, it makes sure that the body’s own cells are not attacked.
The immune system includes the lymph nodes, spleen, bone marrow and thymus, among others – they produce and activate the immune cells. This network is complemented by immune cells such as lymphocytes, macrophages and granulocytes, as well as messenger substances like cytokines. All these systems work closely together to reliably fend off pathogens and keep us feeling well.
Innate and adaptive immunity
Our immune system consists of two closely connected parts that work together to provide protection and adaptability. While one reacts immediately, the other keeps learning throughout life. The result is a finely tuned interplay of rapid response and targeted defense:
- Innate immunity: Reacts immediately to invaders – nonspecific, but fast
- Adaptive immunity: Develops through contact with pathogens and stores defense information (also known as “immunological memory”)
Good to know:
An immune response usually takes place in several steps: recognizing the pathogen, activating the immune cells, fighting it off and then recovering. Studies show that a well-trained immune system reacts faster and can often make infections less severe (source: Netea et al., 2020).
What weakens the immune system?
The immune system is weakened above all by stress, lack of sleep, smoking, an unhealthy diet, environmental toxins and certain medications.
These factors disrupt the renewal of immune cells, raise inflammation levels in the body and throw its natural equilibrium off balance. They often act unnoticed in everyday life: for example through ongoing stress, too little rest or hidden strains. A little mindfulness, however, can help you recognize such influences quickly and actively counteract them.
Chronic stress
Ongoing stress raises cortisol levels: a stress hormone that inhibits inflammatory processes while also suppressing the activity of immune cells. As a meta-analysis (Segerstrom & Miller, 2004) shows, chronic stress can significantly reduce immune function. Short breaks, meditation, regular walks and exercise can help lower cortisol levels and thus support the body’s own defenses.
Lack of sleep
The immune system recovers during sleep. Conversely, lack of sleep leads to reduced antibody production. According to a University of California study, just one week of less than six hours of sleep per night can significantly increase susceptibility to infections.
Smoking, environmental toxins and medications
It’s no secret that cigarettes, alcohol and environmental toxins have a negative impact on our health and our immune system. They cause oxidative stress, put a strain on the detoxifying organs and thus hinder the natural renewal of immune cells. Likewise, antibiotics taken without medical need can weaken the gut flora – and with it around 70 percent of our immune cells.
What weakens the immune system the most?
- Ongoing stress and lack of sleep
- Nicotine and excessive alcohol consumption
- Lack of exercise
- A nutrient-poor, high-sugar diet
- Excessive hygiene and frequent use of antibiotics
How can I tell if my immune system is weakened?
A weakened immune system shows up above all as increased susceptibility to infections: for example, when colds occur more often or last longer than usual.
Constant tiredness, exhaustion, difficulty concentrating or slow wound healing can also point to weakened defenses. The body sends such signals early on – so it’s important to listen to them!
By the way: children, older adults and pregnant women are considered more susceptible, because their immune system is either not yet fully developed or weakened by hormonal and age-related changes.
Our expert tip:
A weak immune system is nothing to take lightly. If you feel constantly tired for weeks or keep getting sick, you should definitely see a doctor.
After an illness, it’s also important to rebuild your immune system in a targeted way: fresh air, light exercise, a vitamin-rich diet and plenty of fluids can help support weakened defenses.
Typical signs of a weakened immune system
A weakened immune system often makes itself felt gradually. If you notice the following signs, it’s worth paying closer attention, as they may indicate that your defenses need support:
- Frequent colds or infections
- Persistent exhaustion
- Increased susceptibility to infections during stressful periods
- Dry mucous membranes or skin
- Slow recovery after illness
How can I build up my immune system?
The immune system can be supported in the long term by specifically encouraging its natural defense mechanisms.
But how exactly can I strengthen my immune system? The key factors are a healthy lifestyle, a nutrient-rich diet and a mindful approach to stress. Herbal remedies, vitamins and high-quality oils can be a useful addition to a healthy lifestyle.
However, a strong immune system doesn’t develop overnight. On the contrary: it takes care, time and inner balance. Regular exercise, restful sleep and fresh air can help support the body’s protective function in the long term. In medicine, the term “strengthening the immune system” therefore refers less to quick, acute help and more to holistic support of the body’s own defenses.
“Boosting” – what’s really behind it
How can I strengthen my immune system? Maybe with an “immune booster”?
What sounds like a quick energy kick is above all a catchy marketing phrase. That’s because the immune system can’t be “overactivated” in the short term or strengthened at the push of a button. Instead, it needs time, rest and consistent care. What matters is balance and an overall healthy lifestyle.
3 immune helpers at a glance
There are lots of tips, home remedies and supposed miracle cures for the immune system out there. But what’s really behind them? Here are the facts:
- Vitamin C: Studies show that vitamin C does not prevent colds but can slightly shorten their duration (e.g. Hemilä & Chalker, 2013).
- Zinc: Contributes to the normal function of the immune system and has a role in the process of cell division.
- Chicken soup: Provides fluids, electrolytes and cysteine – it can feel soothing when you have a cold, but it’s no miracle cure.
Which foods support the immune system?
Foods that are rich in vitamins, minerals and antioxidants are important building blocks of a balanced diet.
A wholesome, plant-focused diet provides the building blocks the immune system needs to do its job. Fiber, phytonutrients and omega-3 fatty acids are among the most important of these. Regularly choosing fresh, unprocessed foods lays a good foundation for greater everyday well-being.
*Less is more: This motto also applies to dietary supplements. Although supplements are very much in vogue, they should only ever be taken in a targeted way (ideally on medical advice). Only then can they provide meaningful support for the body. Too much of a good thing in the form of vitamins or trace elements, on the other hand, can overstimulate the immune system and even have the opposite effect.
Focus on the following when shopping and cooking:
- Fresh fruit and vegetables, especially cruciferous vegetables, berries and citrus fruits
- Spices such as ginger, turmeric, pepper, garlic, mustard and horseradish
- Fermented foods (e.g. sauerkraut, kimchi, yogurt)
- Omega-3 fatty acids from nuts, flaxseed or fish
Avoid where possible:
- High-sugar foods and white flour products
- Excessive consumption of dairy products (can promote mucus production)
- Highly processed products with additives and trans fats
Herbal remedies and home remedies
Nature offers many valuable plants that have been used for centuries and are highly regarded in traditional use. Here’s a selection of natural companions that are especially popular in the colder months:
- Echinacea (coneflower) is traditionally used during cold season
- Propolis is a natural resin collected by bees and a traditional beekeeping product
- Elderberries contain antioxidants and vitamin C
- Rose hips contain natural polyphenols and vitamin C
- Black seed oil provides valuable omega-6 fatty acids
What are the benefits of essential oils and inhalations?
Essential oils from thyme, ravintsara or lemon eucalyptus can feel soothing during cold season and give a sense of easier breathing.
Their fresh scent can support well-being. Gentle steam inhalations with hot water or aroma diffusers that evenly disperse the essential oils throughout the room are especially pleasant. Important: Always use high-quality, pure essential oils and pay attention to your individual sensitivity.
How does exercise affect the immune system?
Regular exercise – ideally in the fresh air – improves circulation and oxygen transport.
Moderate activity can activate immune cells and lower stress hormones. Gentle forms of exercise such as walking, cycling or yoga in particular can thus contribute to good immune defenses. Excessive training, on the other hand, can temporarily weaken the immune system. As is so often the case, finding the right balance is key: exercise should challenge you, not overwhelm you.
Done with your workout? Then small mindfulness rituals, meditation or time in nature can help further promote inner calm. Studies show, for example, that just around 20 minutes in nature can measurably lower cortisol levels (source: e.g. Frontiers in Psychology, 2019).
Our expert tip:
If you exercise in (moderate) sunshine, you can benefit twice over. Sunlight promotes the body’s own production of vitamin D, which contributes to the normal function of the immune system. Just 15–30 minutes of sunlight a day can contribute to stable vitamin D levels. But be careful: UV radiation can put stress on your skin. So it’s best to always use a high-quality sunscreen to protect your skin well.
How does sleep affect the immune system?
Sleep has a direct influence on our immune defenses: it can support them, but also weaken them.
While sufficient sleep can promote the formation and activity of immune cells, lack of sleep leads to reduced immune performance.
Studies show that lack of sleep inhibits the production of certain immune cells and can promote inflammatory processes (see e.g. Garbarino et al., 2021). Regularly sleeping seven to eight hours supports not only physical recovery but also stable, resilient immune defenses.
The four pillars of strong immune defenses
How can I strengthen my immune system? Always keep these four pillars of strong defenses in mind:
- A balanced diet
- Regular exercise
- Enough sleep
- Mindful care of body and mind
What role does the gut (microbiome) play in immune defense?
The gut is one of the most important organs for a strong immune system: around 70 percent of all immune cells are active here.
It decides which substances are allowed into the body and which are kept out. A healthy microbiome – the entirety of the gut bacteria – can protect against pathogens, support the mucous membranes and play a part in regulating inflammatory processes.
*How can I strengthen my immune system? When answering this question, diet should always be taken into account: a varied diet with fresh, unprocessed foods is a good foundation for a diverse microbiome and therefore also for well-functioning immune defenses.
How can you strengthen your gut flora?
A healthy gut flora can be supported in a targeted way above all through diet and lifestyle.
Fiber is especially important, as it serves as “food” for beneficial gut bacteria: it’s found in whole grains, legumes, vegetables and fruit. A high-fiber diet promotes the diversity of these “good” bacteria and thus naturally supports the body’s own defenses.
Fermented foods such as yogurt, kefir, sauerkraut or kimchi also provide valuable probiotic cultures that support the balance in the gut. If you also make sure to get enough exercise, reduce stress and eat mindfully, you create good conditions for a strong, resilient microbiome.
Probiotics and prebiotics for the gut
Probiotics are live microorganisms that, in sufficient amounts, can have positive effects on health. They are found, for example, in yogurt or fermented foods.
Prebiotics, on the other hand, are indigestible fibers, such as inulin from chicory. They are considered food for probiotics and promote their growth.
Both probiotics and prebiotics are essential for the stability of the gut flora. In a healthy gut flora, probiotics and prebiotics occur in natural diversity and together ensure a stable, resilient microbiome.
