How to strengthen your immune system with juicing

 

1. How to get ready for autumn and strengthen your immunity 

The days are relentlessly getting shorter, the leaves are turning into autumn colors, and cooler weather is just around the corner. Unfortunately, autumn is also known for a higher occurrence of colds and infections, so it is essential to prepare for this season and boost your immune system. 

When we return to offices and schools in full numbers after the summer holidays, more human contact means more transmission of bacteria and viruses, which puts greater stress on our immune system. In addition, when spending free time, we begin to stay indoors more often and do not spend as much time outside - where not only is the risk of disease transmission lower, but our vitamin D levels also decrease due to less sun exposure. Studies show that up to 40% of the population has a deficiency of vitamin D in autumn and winter.

In Europe, the average adult experiences 2-4 respiratory illnesses per year, while children experience as many as 6-8. If our immune system is strong and functional, it can protect us against more threats than we are even aware of, and it can also shorten the duration of illness by 1-2 days and reduce its severity. But for the immune system to have these abilities and protect us as much as possible, we must take proper care of it. Immunity is not a switch that starts working overnight - strengthening it is a long-term process. That is why it is important to start as soon as possible, not only when we are already dealing with a cold or illness. It can take our body several weeks before changes in diet and lifestyle show in the strength of our immune system. 

A proper diet and fresh juices are great ways to boost immunity. About 70% of immune cells are located in our intestines, so we should not forget to also support their proper functioning. How to maintain a healthy microbiome is explained below in this article. 

 
2. How the immune system works and why strengthening it is important 

We hear the word “immunity” everywhere, especially in autumn and winter. You probably know that immunity is our defense system, but do you know how it really works and how it changes throughout our lives? 

Innate and adaptive immunity as the body’s security system 

Innate immunity can be understood as immediate protection that we are born with (for example, skin, mucous membranes, or stomach acids). It acts as the first barrier when intruders enter our body. However, this barrier does not distinguish between bacteria and viruses - it reacts to everything the same way. When something still manages to enter the body, white blood cells come into play and attack or destroy the harmful cells. 

If this first barrier is not enough, the smarter second barrier comes into play - adaptive immunity - which learns throughout life. Thanks to adaptive immunity, our body can build antibodies after an infection, and during the next infection the body can react faster and more accurately (this is why vaccinations work). 

Together, innate and adaptive immunity create our personal, complex security system that protects us from outside influences every day. 

 
3. Weakening of immunity 

As already mentioned, our immune system defends against attacks from bacteria, viruses, and toxins 24/7. Every day, up to 70 billion cells in the body die and regenerate, and the immune system constantly checks whether they are faulty. If it does not work as it should (either due to congenital and health reasons or because it is weakened by an unhealthy lifestyle), we can suffer from chronic inflammation, allergies, or autoimmune diseases. 

For example, lack of sleep (less than 6 hours) increases the risk of infection by up to 4× compared to people who sleep more than 7 hours per day. Chronic stress is also a major enemy of our health, because high levels of cortisol weaken the reaction of immune cells. 

Age also plays a big role in the body’s defenses. After the age of 60, immunosenescence begins - the gradual aging of the immune system, which results in a higher susceptibility to infections and may also lead to a weaker response to vaccinations. 
 

4. How to strengthen immunity 

Vitamin C as an immunity booster is a generally known fact - but again, do you know why it is important, how much we need, when, what to combine it with, and in which form to consume it? 

 

Why is Vitamin C important? 

Do you remember the white blood cells that rush into action when something enters our body? Vitamin C stimulates the production of these cells (especially neutrophils and lymphocytes), which fight infections. In addition, it also supports the absorption of iron from plant sources by 3-4×, which is why it is good to combine it with iron-rich foods, such as spinach. Our body cannot produce vitamin C on its own, which is why it is essential to get enough from food. 

How much Vitamin C do we need? 

The official recommended daily dose (according to EFSA) is 80 mg per day. For immune support, the dose can be increased to 200-400 mg per day (studies show that vitamin C can shorten the duration of colds by 8% in adults and 14% in children). 

For reference: 

• 1 orange = approx. 50 mg 
• 1 kiwi = approx. 70 mg 
• 100 ml of fresh orange juice = 40-50 mg 

When to consume Vitamin C 

Vitamin C is water-soluble, meaning the body does not store it and the excess leaves the body through urine. That is why it is good to keep its level steady and divide intake into 2-3 doses during the day. Its blood level peaks about 2-3 hours after consumption. It is not good to take it right before sleep - for some people it can be mildly stimulating and disrupt sleep. 

What to combine Vitamin C with and what to avoid 

As already mentioned, thanks to vitamin C, iron absorption (from spinach, lentils, pumpkin seeds) increases by 3-4×. So if you make yourself fresh orange juice, it’s a good idea to add a few spinach leaves - this combo will only benefit your body! But be careful with coffee or tea - the polyphenols in these drinks block iron absorption from food. 
Together with flavonoids (in citrus fruits, blueberries, strawberries, pomegranate), vitamin C prolongs its effect and antioxidant activity in the body. 

In which form should Vitamin C be consumed? 

Fresh juice from a juicer - Vitamin C is very unstable and sensitive to light, heat, and air, so it is best to drink juice immediately after juicing or use vacuum containers that slow down oxidation. Slow juicers are an advantage here, because thanks to gentle pressing and low speed, vitamin C is better preserved. 

Whole fruit - less concentrated, but more complete Fruit contains less vitamin C per volume than a glass of juice, but it adds something extra - fiber, which slows sugar absorption and supports a healthy gut microbiome. The best option is therefore to combine juices and whole fruit. For example, have fresh juice in the morning for a quick vitamin boost, and whole fruit in the afternoon for fiber and satiety. 

Supplements - Tablets or capsules with vitamin C have a bioavailability of about 70-80%, which means the body uses only part of the vitamin they contain. They also lack other nutrients (flavonoids, fiber, enzymes). Supplements are suitable rather as a backup on days when we don’t get enough vitamin C from food, but they cannot replace fresh food. 

 
5. Other nutrients and foods that support immunity 

Flavonoids (citrus fruits, berries, green tea) These are natural antioxidants that have anti-inflammatory effects, support the function of immune cells, and protect against oxidative stress. They work best when combined with vitamin C, which increases their antioxidant effect. Have a citrus juice or smoothie with a handful of berries during the day - ideally in the morning, when the body will appreciate antioxidants to start the day with energy.

 
Vitamin D (sunlight, oily fish - salmon, mackerel - eggs, fortified dairy products) Vitamin D is important because it allows our immune cells to even start working properly. Without it, T-lymphocytes (the cells that directly attack viruses and bacteria) cannot activate effectively. It is best absorbed with fat (for example, with fish, eggs, or oil). 

Zinc (pumpkin seeds, legumes, whole grains, beef) Zinc supports the development and activation of immune cells and shortens the duration of colds. Absorption of zinc can be worsened by high intake of grains (which contain phytates). It helps to combine it with proteins (such as meat or eggs). 

Garlic and onions: They contain allicin and sulfur compounds, which have natural antibacterial effects and can shorten the course of colds and support the gut microbiome. They are most effective raw, because heating destroys part of the active substance (allicin). 

Probiotics and fermented foods (sauerkraut, kefir, yogurt, kimchi) As already mentioned several times, up to 70% of immune cells are located in the intestines, so we should support the microbiome with sauerkraut, kefir, yogurt, or the popular kimchi. The effects of probiotics are increased when they have “food” - so-called prebiotics (fiber from fruits and vegetables). Combine sauerkraut or kefir with fresh vegetable or fruit juice → probiotics + prebiotics = a healthy microbiome! 

Beta-carotene (carrots, sweet potatoes, pumpkin, spinach) Supports the health of mucous membranes, which are the first barrier against infections. It is fat-soluble, so it is absorbed better when consumed with a little oil or nuts.  Juice made from carrots or pumpkin with a few drops of vegetable oil (e.g., flaxseed or olive oil) will increase the use of beta-carotene. 
 

6. Other factors supporting immunity 

Regular exercise - Moderate exercise (brisk walking, running, cycling, swimming, Pilates, etc.) 3-5 times a week strengthens immune reactions and reduces the risk of respiratory infections. But as the saying goes, too much of anything is harmful - very demanding activity and extreme exhaustion can temporarily weaken immunity. 

Enough sleep - We already touched on sleep in this article. If sleep is shorter than 6 hours, the risk of catching a cold is up to 4× higher than if sleep lasts more than 7 hours. The ideal is 7-8 hours of sleep; women need on average 20-30 minutes more sleep than men. For children and teenagers, sleep is even more important and essential for their growth and proper immune system development. 

Stress relief - Chronic stress increases the level of cortisol, which reduces the activity of immune cells, and the body is therefore more prone to infections. It is important to reduce stress with activities that help you relax - whether it is quality rest, sports, time in nature, hobbies, or breathing exercises and meditation. 

Reducing alcohol and eliminating smoking - Smoking damages the mucous membranes of the respiratory tract and weakens their protective function. Excessive alcohol suppresses the formation of white blood cells that attack and destroy harmful cells, which again reduces the defenses of our body and immune system. 
 
If you have read this article all the way here, you have already taken the first step toward strengthening your immunity and you now know how to do it! As a bonus, we have prepared a few recipes for fresh juices that will boost your immunity (and now you also know exactly how and where they will help you :) ). 
 

7. Quick juice recipes to boost immunity 

 

1. Citrus Elixir 

• 2 oranges 
• 1 grapefruit 
• 1 lemon 
• a piece of ginger (2-3 cm)

👉 High dose of vitamin C + flavonoids, ginger with anti-inflammatory effects. A perfect morning start. 

2. Green Booster 

• 2 apples 
• a handful of spinach 
• 1 kiwi 
• ½ cucumber

👉 Combination of vitamin C + iron → vitamin C from kiwi and apples helps absorb iron from spinach. 

 

3. Carrot-Pumpkin Immunity 

• 2 carrots 
• 1 piece of pumpkin (150 g) 
• 1 apple 
• a few drops of olive or flaxseed oil (added after juicing)

👉 Rich source of beta-carotene (vitamin A) + vitamin C from apple. Oil increases beta-carotene absorption.

 
4. Fermented Twist 

• 2 apples 
• 2 carrots 
• 1 tbsp sauerkraut juice

👉 Combination of fresh juice (vitamin C, beta-carotene) and probiotics from sauerkraut → supports the gut microbiome, which contains up to 70% of immunity. 

5. Autumn Immunity Shot 

• 1 lemon 
• 1 orange 
• 3 cm fresh turmeric root or 1 tsp turmeric powder 
• a pinch of black pepper (increases curcumin absorption up to 20×)

👉 Strong anti-inflammatory and antioxidant drink - ideal as a small shot during cold days. 
 
  
 
References 
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Carnegie Mellon University (2015). New Research Confirms Lack of Sleep Connected to Getting Sick. [online] Available at: https://www.cmu.edu/news/stories/archives/2015/august/sleep-and-sickness.html  [Accessed 4 Sep. 2025]. 

Centers for Disease Control and Prevention (CDC) (2024). About Sleep – Getting enough sleep (recommended hours by age). [online] Available at: https://www.cdc.gov/sleep/about/index.html [Accessed 4 Sep. 2025]. 

Cleveland Clinic (2022). What You Should Know About Your Gut Health. [online] Available at: https://health.clevelandclinic.org/gut-health [Accessed 4 Sep. 2025].

 
Cochrane Review (2013). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. [online] Available at: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/full  [Accessed 4 Sep. 2025]. 

European Food Safety Authority (EFSA) (2013). Scientific Opinion on Dietary Reference Values for vitamin C. EFSA Journal, 11(11): 3418. [online] Available at: https://www.efsa.europa.eu/en/efsajournal/pub/3418  [Accessed 4 Sep. 2025]. 

Fruit Juice Science Centre (2021). Vitamin C stability in fruit and vegetable juices. [online] Available at: https://fruitjuicesciencecentre.eu/fr/research/jus-de-fruits-et-de-legumes-associes-a-un-renforcement-de-la-vitamine-c   [Accessed 4 Sep. 2025]. 

Harvard Health Publishing (2019). The importance of vitamin C. [online] Available at: https://www.health.harvard.edu/staying-healthy/by-the-way-doctor-whats-the-right-amount-of-vitamin-c-for-me   [Accessed 4 Sep. 2025]. 

Martineau, A.R., et al. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ, 356, i6583. [online] Available at: https://www.bmj.com/content/356/bmj.i6583 [Accessed 4 Sep. 2025]. 

National Institutes of Health (NIH) – Office of Dietary Supplements (2025). Vitamin C — Fact Sheet for Health Professionals. [online] Available at: https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/ | mirror: https://digitalmedia.hhs.gov/storefront/showContent/18449 [Accessed 4 Sep. 2025].

National Institutes of Health (NIH) – Office of Dietary Supplements (2022). Vitamin D — Fact Sheet for Health Professionals. [online] Available at: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/  [Accessed 4 Sep. 2025]. 

National Institutes of Health (NIH) (2019). Alcohol and the Immune System. Alcohol Research: Current Reviews, 41(1), 1. [online] Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6826793/ [Accessed 4 Sep. 2025]. 

Nieman, D.C. and Wentz, L.M. (2019). The compelling link between physical activity and the body’s defense system. Journal of Sport and Health Science, 8(3), 201–217. [online] Available at: https://pubmed.ncbi.nlm.nih.gov/31193280/ and open access: https://pmc.ncbi.nlm.nih.gov/articles/PMC6523821/ [Accessed 4 Sep. 2025]. 

Shoba, G., et al. (1998). Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Medica, 64(4), 353–356. [online] Available at: https://pubmed.ncbi.nlm.nih.gov/9619120/  [Accessed 4 Sep. 2025]. (supports the “black pepper increases curcumin absorption ~20×” note)