Probiotics and Immunity

It’s as inevitable as pumpkin spice lattes and pretending you’re not in when trick or treaters call (just us?). Cold and flu season is hurtling towards us. Which means you're probably starting to think about getting your immune system into its hardest working shape.

If there’s one fact that’s helped us understand immunity and how to improve it, it’s this: the wellness of your gut and the effectiveness of your immune system go hand in hand.

Let’s take a closer look at that link and investigate just how we can harness this knowledge to improve immunity ahead of those colder, darker and germier months...

Gut Health and Immunity

Research tells us that around 70 to 80% of our immunity resides in your gut[i], underlining the strong link between gut health and the immune system.

Gut health and the immune system: the link

Made up of billions of microscopic organisms, the gut’s microbiome is home to a wealth of ‘good’ bacteria. This bacteria is vital for immunity, responding locally to invasion by bad bacteria while helping to regulate the body-wide immune system. This ensures that when you’re exposed to infection or injury, the immune system reacts appropriately, attacking baddies while leaving healthy cells alone.

The largest immune organ in the body[ii], the gut plays several roles in keeping us feeling tip-top:

Teaching the immune system to differentiate between healthy and unhealthy cells
Minimising bad bacteria such as pylori by limiting their access to nutrients
Producing short chain fatty acids for a strong gut barrier (keeping bacteria from reaching the bloodstream) and proper inflammatory response

Do gut problems mean poor immunity?

An occasional dodgy belly isn’t an indicator that your gut health is poor or that your immunity is low. After all, we’re all prone to, bloating, cramping and (ahem) increased toilet time after an evening of ill-advised overindulgence. Likewise, food intolerances, stress, smoking and alcohol can all contribute to stomach issues.

Low immunity is most likely to produce symptoms such as:

Catching colds, the flu and other common illnesses more often and struggling to shake them off
Healing slowly after a cut, scrape or other injury
Regular development of infections like sinusitis and tonsilitis or cold sore flare-ups
Feeling exhausted, even though you seem to be sleeping well

What causes low immunity?

If your immune system is struggling to do its thing it could be that your gut is in what’s known as dysbiosis[iii]. However, gut dysbiosis is just one of several potential causes of low immune function.

Aside from pre-existing autoimmune disorders (which could be linked to microbial dysbiosis[iv]), there’s also a whole range of other, less obvious causes of low immunity. In particular, stress can mess with your immune system and with your gut all at once[v]. A lack of quality sleep may also reduce immunity[vi]. Then there are poor lifestyle choices such as smoking[vii], alcohol consumption[viii] and a bad diet[ix], all of which can contribute to a dysfunctional immune system too.

Probiotics and Your Immune System

If your immune system is so strongly linked to the health of your gut, does it follow that probiotics can support immunity?

What are probiotics?

Live bacteria and yeasts, probiotics have gained a reputation as something of a wonder-supplement. A decent source of probiotics will deliver live ‘good’ bacteria to the intestinal system once consumed. This helps restore balance to the gut, where bacteria is necessary for a well-functioning digestive system.

Probiotic strains you’ll commonly see in supplements include:

Bifidobacterium lactis
Bifidobacterium longum
Lactobacillus rhamnosus
Lactobacillus acidophilus

What do probiotics do?

Think of your gut microbiome as an army at constant battle with invading bad bacteria. While protecting your intestines from those nasty incomers, your troops can fall on the intestinal battlefield. Which means you’ll need to send in reinforcements. Those reinforcements – new bacteria – reup your army, meaning your gut lives on to fight another day.

Generally, there’s no harm in adding probiotic supplements to your regime for peace of mind. And indeed, there are times when you might be advised to take probiotics over the long or short term:

When taking antibiotics: medical experts often suggest pairing probiotics with antibiotics, which can attack good bacteria along with the bad[x]
When you have a stomach bug: research is conflicted on probiotics’ effectiveness in aiding cases of gastroenteritis, but some probiotics are seen to shorten cases of diarrhoea[xi]
If you have IBS: probiotics may be beneficial for those with irritable bowel syndrome[xii]

What about prebiotics?

Prebiotics are a specific type of dietary fibre. They provide probiotics with the food (or should we say rations?) they need to do their job. Most of us get enough fibre in our diet to keep our good bacteria nourished, but if you want to be extra sure the troops are well-fed snack on:

Bananas
Oats
Onions and leeks
Asparagus
Avocado
Flaxseeds

Probiotics for Immunity: How to Boost Immune Health

Good gut health is vital for an immune system that kicks butt when illnesses and infections try to take you down.

Top tips for better gut health

There are many free and easy ways to improve gut health, including:

	The Research	How To
Drinking more water	Studies show that water is essential to reduce the risk of gut dysbiosis[xiii]. It is also important for the maintenance of vital Th17 immune cells[xiv]	The NHS recommends drinking six to eight cups/glasses of fluid a day. Soft drinks, coffee, tea, squash and juice count. Minimise your intake of added sugar, which can disrupt the microbiome[xv].
Getting a good night’s sleep	Research has proven that disrupted or irregular sleep has a negative effect on the microbiome. Those with irregular sleep patterns may have higher levels of unfavourable bacteria in their gut[xvi]	Maintain a regular sleep schedule to avoid gut imbalance-causing ‘social jetlag’[xvii]. Create a bedroom that encourages uninterrupted sleep.
Eating a balanced diet	A healthy diet is crucial for microbial diversity and wellbeing[xviii]. Studies underline that diet is particularly influential in the health of the intestinal mucosal immune system[xix]	Limit your intake of processed foods, associated with poor gut health[xx]. Lean into probiotic-packed fermented foods. Aim for diversity in your daily diet[xxi].
Reducing stress	Everyday stress and anxiety can disrupt the microbiome, both long and short-term[xxii]	Switch off from work accounts during home time. Try meditation, yoga or other relaxation techniques. If stress becomes too much consult your GP.

Immunity supporting probiotic foods

Eating for gut health and immunity is easier than you think. Add some of these foods to your diet for better immune support:

Fermented foods: Tofu, kimchi, yoghurt and sauerkraut are just some of the fermented foods proven to deliver good bacteria direct to your gut. Ongoing research suggests these foods could have nutritional and therapeutic effects on chronic inflammatory disorders[xxiii]

Fibre: Foods that are high in fibre are shown to be essential for a healthy microbiome[xxiv]. See above for good examples of gut-friendly fibre-rich foods.

Collagen-rich foods: Early research into collagen, found in bone broth, eggs, meat and nuts, suggests that it could be beneficial for your gut and your overall health[xxv].

Probiotic supplements and the immune system

Probiotics have a potentially positive effect on the diversity and health of gut microbiota and, in turn, on immunity[xxvi]. Supplementation is a simple solution that can be deployed alongside dietary improvements and lifestyle changes to aid gut health. Probiotic supplements may be particularly beneficial for those on a restricted diet.

When choosing a supplement, opt for a high quality, research-backed product containing proven, live bacterial strains.

References:

[i] https://pmc.ncbi.nlm.nih.gov/articles/PMC8001875/

[ii] https://pmc.ncbi.nlm.nih.gov/articles/PMC4714863/#:~:text=The%20mammalian%20intestinal%20tract%20is,collectively%20known%20as%20the%20microbiota.

[iii] https://www.nature.com/articles/nri.2017.7

[iv] https://pmc.ncbi.nlm.nih.gov/articles/PMC9271567/

[v] https://pmc.ncbi.nlm.nih.gov/articles/PMC11546738/

[vi] https://pmc.ncbi.nlm.nih.gov/articles/PMC8602722/

[vii] https://pmc.ncbi.nlm.nih.gov/articles/PMC5352117/

[viii] https://www.nhs.uk/conditions/alcohol-misuse/risks/#:~:text=Long%2Dterm%20alcohol%20misuse%20can,risks%20associated%20with%20alcohol%20misuse.

[ix] https://pmc.ncbi.nlm.nih.gov/articles/PMC9772031/

[x] https://pmc.ncbi.nlm.nih.gov/articles/PMC3601687/