Do Probiotics Really Help Your Immune System?

Do Probiotics Really Help Your Immune System?

Yes, some probiotic strains have been studied for their effects on immune function, but the evidence does not show that every probiotic works in the same way. Probiotics interact with the gut microbiome and immune cells, and some human trials have reported changes in immune markers or immune-cell activity.

The important detail is that probiotic effects are strain-specific. A result from one strain cannot automatically be applied to another strain or product.

How Is the Gut Linked to Your Immune System?

Your gut is home to trillions of microorganisms, collectively known as the gut microbiome. These microbes live alongside your intestinal lining interact with the intestinal lining, which acts as a protective barrier between what's inside your gut and the rest of your body. This barrier is a busy meeting point - gut microbes and the compounds they produce are constantly in communication with the immune cells in the gut, helping keep the barrier strong and teaching your immune system how to respond to disturbances.

When this relationship is in balance, it supports a healthy, well-regulated immune response.

How does the gut communicate with other organs?

The effects of the gut microbiome can extend beyond the digestive tract. Research describes several gut-organ communication pathways, including the gut-lung axis. (McAleer and Kolls.)

• Gut-lung axis: Gut microbes and their metabolites can influence immune responses in the respiratory system. (McAleer and Kolls.)
• Gut-brain axis: The gut and brain communicate through interconnected neural, hormonal and immune pathways. (Mazziotta et al.)
• Gut-liver axis: Blood from the gut carries nutrients and microbial products towards the liver, creating another route for gut-derived signals.

Probiotics may influence immune function through immunomodulation

One reason probiotics are studied for immune health is their ability to interact with the body's immune cells. Scientists refer to this process as immunomodulation, the ability to influence or regulate immune responses.

Research suggests that certain probiotic strains can:

• Interact with immune cells in the gut lining
• Influence the production of signalling molecules called cytokines
• Support the activity of regulatory immune cells
• Help maintain a balanced inflammatory response

What Does the Research Actually Show?

If you're looking for the best probiotics for immune system support, the short answer is: some probiotics appear to help support immune function, but not all probiotics work in the same way.

One of the biggest discoveries in recent years is that the gut and immune system are closely connected. Researchers now know that gut microbes can influence how immune cells communicate, respond to threats and maintain balance throughout the body, including in the respiratory system. (McAleer and Kolls, 2018; Mazziotta et al., 2023).

With strain specificity in mind (Mazziotta et al., 2023; Lehtoranta et al., 2020), here's what some individual strains have shown in human studies:

In a 12-week randomised controlled trial involving elderly adults receiving enteral tube feeding, the strain Bifidobacterium longum BB536 increased levels of beneficial bifidobacteria in the gut and helped maintain natural killer cell activity, an important part of the body's first line of immune defence. (Akatsu et al., 2013).

In an eight-week randomised, placebo-controlled, double-blind trial involving 100 adults, heat-treated Lactiplantibacillus plantarum nF1 was associated with changes in immune markers, including increased interleukin-12 levels and improved natural killer cell activity in certain participant groups. (Hong et al., 2024).

Looking at the bigger picture, a 2020 review of preclinical and clinical studies found that certain probiotic strains may support immune responses and could help reduce the risk or duration of some viral respiratory tract infections in specific populations. The authors emphasised that these effects vary between strains and study groups. (Lehtoranta et al., 2020)

So, what does this mean for you?

The current evidence suggests that certain probiotics may support immune health by working through the gut microbiome and interacting with immune cells. However, there is no single "immune probiotic" that works for everyone.

When choosing a probiotic, it's worth looking beyond the number of strains or the number of billions of bacteria. What matters most is whether the strains have been studied for the benefit you're looking for.

However, because probiotic effects are strain-specific, findings from published studies cannot automatically be assumed to apply to the exact strains contained in this product unless those strains have been clinically tested.

Together, these species represent some of the most widely studied groups of probiotic bacteria in gut and immune health research. By combining multiple probiotic species, the formulation aims to support a diverse gut environment rather than focusing on a single mechanism.

The formula also includes fructo-oligosaccharides (FOS) and galactomannan, prebiotic fibres that provide food for beneficial gut bacteria. When these fibres are fermented by gut microbes, they produce metabolites that help maintain the gut barrier and support communication between the gut microbiome and the immune system.

By combining probiotics and prebiotic fibres, the formulation takes a synbiotic approach, designed so that the two synergise: fibres act as fuel for our gut bacteria, helping the microbes in the probiotic formulation and existing microbes in the host organism thrive together.

The bottom line is this: your gut and immune system are in constant conversation with each other, and certain probiotic strains can support this relationship. However, there is no one size fits all probiotic formulation; the best choice is built around well-studied species combined with prebiotic fibres, used alongside the everyday basics of good sleep, movement, stress management and a fibre-rich diet.

Glossary

• CFU: Colony-forming units, a laboratory measure used to estimate viable microorganisms in a probiotic product.
• Cytokines: Signalling proteins that help immune cells communicate.
• Gut microbiome: The community of microorganisms living in the digestive tract.
• Immunomodulation: The regulation or alteration of an immune response.
• Natural killer (NK) cells: Immune cells involved in recognising and responding to infected or abnormal cells.
• Prebiotic: A substrate used by microorganisms that contributes to their activity or composition.
• Probiotic: A live microorganism that, when administered in adequate amounts, confers a health benefit on the host.
• Short-chain fatty acids: Small fatty-acid metabolites produced by gut microbes during fermentation of certain substrates.