Your gut and immune system work closely together. Explore the research on probiotics and respiratory infections, and how to choose a supplement for your daily routine.
🕒 6 min read
If you're looking to support your immune system before heading into peak cold and flu season, the health of your gut is one area to consider. More specifically, the trillions of microorganisms that make up the gut microbiome, which includes bacteria but also fungi and viruses.
These microbes help perform crucial roles in the body, including digesting food and producing useful compounds. The gut connects to the immune system through a series of pathways known as the gut-immune axis. Researchers are exploring how particular probiotic preparations might influence this relationship.1
The gut-immune axis
The precise mechanisms by which the gut influences immunity are not yet fully understood. Immune cells in the gut interact with the microbiome, and this relationship works in both directions: immune activity can affect gut microbes, while microbial activity can influence immune responses.
Your gut microbes are as individual as your fingerprint. Diet, medicines and other factors can affect their composition. Find out more about the gut microbiome.
Dysbiosis
A disturbance in the composition or function of gut microbes is often called dysbiosis. It is studied in relation to a range of health conditions, but frequent colds do not, by themselves, diagnose a gut imbalance. Persistent symptoms deserve a broader assessment.
What exactly are probiotics?
Probiotics are live microorganisms that provide a health benefit when consumed in an adequate amount. They are found in specific foods and supplements. Their effects depend on the preparation: evidence for one strain and purpose should not automatically be applied to another.4 For a general introduction, read our guide to what probiotics are.
The effects of probiotics on colds and respiratory infections
A 2022 Cochrane review examined 24 studies, with data from 6,950 participants available for analysis. It found that probiotics may reduce the likelihood of upper respiratory tract infections and shorten an episode by about 1.22 days on average. Certainty was low for these outcomes, while evidence for fewer repeated infections and less prescribed antibiotic use was moderately certain.2
The results are encouraging, but studies used different strains, servings and populations. They do not show that all products have the same effect, or that a probiotic treats flu. The review investigated prevention over time rather than an instant remedy once symptoms begin.
Best probiotics for immunity: how to choose
The best probiotic for immune-system support is the one whose formulation and evidence fit your intended use. Think about whether you want a live-culture product, a combination with fibre, or a formula that also supplies nutrients for normal immunity.
- Look for a clear formulation: named strains help you identify exactly what a product contains.
- Match the evidence to the goal: digestive research and respiratory-infection research answer different questions.
- Consider the whole formula: added nutrients have benefits of their own.
- Choose a practical routine: compare daily servings, dietary suitability and storage instructions.
A higher bacteria count or more strains is not automatically better.1 Explore our probiotic supplements category to compare the options. Here are two formulations featured in this guide.
A combination of cultures, fibre and zinc
Triple Action Biotic combines live cultures with chicory root fibre, tributyrin, zinc and biotin. The recommended two-capsule daily serving supplies 20 billion CFU and 2.5mg zinc. Zinc contributes to normal immune function; this is a nutrient benefit, separate from the research on probiotic strains.5
Triple Action Biotic
Live cultures, fibre and added nutrients
- 20 billion live cultures per two-capsule daily serving
- With chicory root fibre and tributyrin
- Added zinc for normal immune function
- Includes biotin
A live-culture formula with five named strains
Super20® Probiotic supplies 20 billion live cultures per capsule from five strains, including Lactobacillus acidophilus NCFM® and Bifidobacterium lactis Bi-07. It is a formulation option for readers who prefer a culture-focused supplement.
Super20® Probiotic
A culture-focused supplement
- 20 billion live cultures per capsule
- Five named strains, including NCFM® and Bi-07
- Vegan-friendly capsules
These examples show differences in formulation. The wider respiratory-infection evidence is not proof that either finished product prevents infections.
Diet and the microbiome
Diet is one of the main influences on gut microbiota. A varied diet containing fruit, vegetables, wholegrains, pulses and other fibre sources is a useful starting point. A supplement can fit alongside this routine.
Live yoghurt and kefir can supply live cultures. Fermented foods vary: baked sourdough bread and many commercial pickles do not contain live cultures when eaten. Check the preparation rather than assuming every fermented food is a probiotic.1
What about prebiotics and postbiotics?
Prebiotics are substances selectively used by microbes to provide a health benefit. Foods such as onions, garlic, leeks and chicory can supply prebiotic ingredients. Some supplements contain chicory-derived fibre.
Postbiotics are preparations of non-living microorganisms or their components with demonstrated benefits. They are not simply whatever is left after digestion. Tributyrin, which appears in some combination products, is a source of butyrate and is different from an inactivated microbial preparation.4 Read more about postbiotics and gut health.
Sleep and everyday habits
Studies have linked sleep quality with gut-microbiome diversity, although an association does not establish cause and effect.6 Aim for a routine that supports your overall wellbeing, including regular meals, activity and sleep.
Using probiotics in your routine
Follow your chosen product's directions and store it as instructed. Allow time for a consistent routine, rather than expecting an immediate immune effect. If you have a weakened immune system or an existing medical condition, speak to your doctor before taking live-culture supplements.3
Compare formulations in the Healthspan probiotics range.
Probiotics and immunity FAQs
What are the best probiotics for the immune system?
Start with your goal and compare the exact strains, research and formulation. A named strain makes it possible to check what was studied. For a product combining live cultures with a nutrient that supports normal immunity, look at the zinc content too. The two options above illustrate different approaches, rather than a universal ranking.
Can probiotics help prevent colds?
The 2022 Cochrane review found that probiotics may reduce the chance of upper respiratory tract infections and shorten episodes. Confidence varied across outcomes, and the studies used different preparations. These promising findings do not establish that every probiotic supplement will prevent colds.2
How long should I take probiotics for immune support?
Think in terms of a consistent routine rather than an immediate effect. Many respiratory-infection studies ran for around three months or longer. That is a research timescale, not a guaranteed deadline for a particular product. Follow its daily directions and review whether it suits your needs.2
Is a higher CFU count always better?
CFU describes the number of live microorganisms, but a bigger number is not an automatic measure of effectiveness. A useful comparison considers the strains and the serving tested for your intended purpose. Choose the formulation that fits your goal, rather than relying on strength alone.1
Can I take probiotics every day?
Many products are designed for daily use. Follow the label and use a consistent time that is easy to remember. If you have a medical condition or weakened immunity, ask your doctor before starting live-culture supplements.3
Can fermented foods replace a probiotic supplement?
Live yoghurt or kefir can be part of a varied diet. Supplements offer a measured serving of specified cultures. Food and supplement preparations differ, so choose according to your diet and preferences; not all fermented foods contain live microbes by the time they are eaten.1
Do probiotics replace vitamin C, vitamin D or zinc?
These are different parts of a nutritional routine. Probiotics supply live microorganisms, while vitamins and minerals have their own roles. Zinc, vitamin C and vitamin D contribute to normal immune function. Check what is already in your supplements before adding a combination product.5
What is the difference between prebiotics, probiotics and postbiotics?
Probiotics are live microorganisms, prebiotics are substances used by beneficial microbes, and the scientific postbiotic definition refers to non-living microbes or their components with demonstrated benefits. Product terminology varies, so it helps to look at the actual ingredients as well as the name.4
How should I store probiotic supplements?
Follow the pack's storage instructions and keep capsules in their original packaging. The featured Healthspan products specify a cool, dry place. Some other preparations need refrigeration, so check your own product rather than assuming the same storage applies to every probiotic.
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