What are Probiotics? A Beginner's Guide to Gut Health

What are probiotics?

It’s fair to say the gut is the unsung hero when it comes to our biological and physiological systems.

But, did you know? The gut is also crucial for our overall well-being. 

It’s referred to by many as the ‘second brain’ due to its key role in so many aspects of health—human health benefits that extend far beyond digestion.

SmartFact: Around 70% to 80% of our immune system is located within the gut, highlighting its role in our body's defence against pathogens.

And, what about its role in mental health, disease prevention and even weight loss?

Let’s take a deep dive into all things gut health and probiotics to find out how you can nurture a thriving gut microbiome for optimal health.

Let’s dive in.

What are Probiotics?

Probiotics are living microorganisms commonly referred to as "good bacteria". They’re found naturally in our digestive systems.

They work by maintaining a balance between the good and bad bacteria in our guts, which we need to maintain the best health.

It might seem abstract, but like so many of the body functions that go on inside us—it’s one that is vital and incredibly powerful, even if we are unaware of it as we go about our everyday lives..

Did you know that probiotics play a crucial role in our digestive health as they actually support food breakdown and the proper absorption of essential nutrients? That’s pretty amazing when you think about it. 

Often people go for fermented foods—like in many countries in Eastern Europe, and Asia—with choices such as kimchi, sauerkraut, kefir, and yoghurt, all providing a great hit of natural probiotics.

But another easy and effective way is through the use of probiotic supplements.

What do Probiotics do?

Probiotics are live microorganisms such as bacteria and yeasts that are beneficial to human health when consumed.

They help maintain a balance of beneficial bacteria in the gut and support digestive health. 

They are a kind of defence against harmful bacteria and assist in immune function too. Very important, indeed.

Why Take Probiotics?

Probiotics are living microorganisms that have some awesome health benefits — when consumed in the right amounts.

SmartFact: They have long been studied for their potential health benefits, which focus on improving gut health and boosting general wellbeing.

Why is this the case?

Well, because the gut microbiome plays a key role in overall health as it’s involved in metabolism, digestion, and immune system function.

Let’s check out their impressive accolades below as we cover their benefits.

What are the Benefits of Probiotics

Probiotics have gained recognition for their potential benefits in promoting both mind and body health. 

There have been lots of positive studies that shed light on probiotics and their link to various aspects of our well-being.

Let’s take a look at some of the main areas.

1. Supports digestive health

Research suggests that probiotics can alleviate symptoms of digestive disorders like diarrhoea, IBS (irritable bowel syndrome), and constipation.

They get to work by restoring the healthy balance of gut bacteria—which we all need to operate our digestion effectively to make sure our overall gut health is balanced and working at its best. 

They may also have a small impact on the main physiological functions of the gastrointestinal tract, such as digestion, absorption, and propulsion.

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2. Improves immune function

It isn’t just digestion that is a health benefit of probiotics, but the immune system gets a shout-out, too.

It’s interesting to learn that certain strains of probiotics can enhance the body's immune response (1) and protect against respiratory infections.

Who doesn’t love something that can help protect you from getting coughs and chest infections?

This is great news for everyone but especially those who are prone to frequent infections. 

3. Mental wellbeing improvements

The gut is an amazing thing.

There are studies that show probiotics may actually help us feel happier, with links to their help in alleviating symptoms of depression and anxiety. 

What does that mean? Well, it means that probiotics may have an impact on mental health (2)—which is huge news.

Probiotics have even been linked to the relationship between gut microbiota and the central nervous system.

The gut-brain axis, a bidirectional communication pathway between the gut and the brain, has attracted quite a lot of attention in recent years. 

It’s been proven that the gut microbiota can influence brain function and mental health, and probiotics may play a role in this process. 

To experience the potential benefits, it is recommended to choose a high-quality probiotic supplement or consume probiotic-rich foods. 

But always consult with a healthcare professional first, especially for those with specific health concerns.

4. Better skin

Yes, you read that correctly.

Good gut health through the right amount of probiotics can actually show its benefits through your skin.

While it’s still being investigated, there is some evidence to suggest that a healthy gut is important for maintaining healthy skin. 

Incredibly, the gut and skin are connected through the gut-skin axis. This also involves the nervous system, immune system and various signalling pathways, which create a communicative passage between the gut and skin.  

Improved gut health may result in improved skin health, as the microbiome in the gut can influence the composition and function of the skin microbiome, among other things. 

There’s even research to suggest certain strains of probiotic bacteria help alleviate skin conditions like acne or eczema (3).

So, having a healthy diet and ensuring your probiotics are topped up can assist with having better skin—who knew?

5. Assist in reducing inflammation

The gut plays a big role in fighting inflammation and maintaining immune function.

It’s all down to the gut microbiota, which helps prevent inflammation by regulating the immune system.

This microbiota can produce something called metabolites that help reduce inflammation, such as short-chain fatty acids. These metabolites modulate the immune system and promote the growth of beneficial bacteria.

Basically, when your gut is balanced and in good health, it supports immune cells. In turn,  it can get rid of pathogens and eliminate foreign substances. From your system.

SmartFact: Being in great health is having good gut health.
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6. Protects the gut

Probiotics may reinforce the intestinal mucosal barrier (4), which helps to protect the gut from harmful agents. 

The mucosal barrier is a defence mechanism against pathogens and other harmful items. 

There are two layers of mucus that help to protect the gut by forming a physical barrier. They act as a filtration system which allows nutrients and other good molecules in whilst stopping the harmful agents from coming in.

There’s a lot more complex information out there on the mucosal barrier, but trust us—gut microbiota to maintain the integrity of the gut.

That said, let’s be clear.

We can’t make generalisations.  It’s important to know that the specific effects of probiotics depend on factors like individual variations—the strain used and the dosage.

What is Good Bacteria?

Also known as ‘friendly bacteria’, good bacteria refers to certain types of healthy bacteria that prove positive health effects on the body.

It’s considered ‘good’ because this type of bacteria can support various bodily functions making it a ‘beneficial bacteria’ in its ability to maintain a healthy balance with our microbial communities.

Microbial communities are diverse populations of microorganisms that inhabit places in our body such as the gut, mouth, respiratory tract, reproductive system, and skin.

The most well-known group of bacteria is probiotics which are live microorganisms. And if consumed in the right amount, these magic strands of gut bacteria offer all the health benefits we’ve discussed above.

Probiotics can include strains like Bifidobacterium and Lactobacillus, to name a few. These bacteria are naturally present in our bodies, especially in the digestive system. 

It's worth noting that finding the right balance of good bacteria is essential. 

There are various strains and species of bacteria, each with different roles and effects on our bodies.

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What is Live Bacteria?

It is pretty much what it sounds like—living probiotics. These microorganisms help human health when you consume the right amount.

Live bacteria actually includes both good and bad bacteria and simply refers to any bacteria that is alive and active. 

Probiotic bacteria are a specific subset of live bacteria that have demonstrated health-promoting effects when consumed in adequate amounts.

Types of probiotics

Lots of different types of bacteria are classified as probiotics, and they all have different benefits.

For example, lactobacillus is the most common type of probiotic. You can find it in yoghurt (yum) and fermented foods. Different strains can help people who can’t digest lactose.

Another is bifidobacterium. It can be found in some dairy products and may help ease the symptoms of irritable bowel syndrome (IBS) and a few other conditions.

Saccharomyces boulardii is a year found in probiotics. It seems to help fight diarrhoea and other digestive problems.

What are the side effects of probiotics?

It’s important to know that whilst probiotics have plenty of health benefits they also have potential side effects.

Don’t worry, they are generally safe for most people. But, here at SmartProtein, we’re all about balance. So, let’s look at the potential side effects of taking probiotics.

Digestive Symptoms

Ironically, there are a few studies that show there are gastrointestinal issues for some people when they have probiotics.

These include abdominal discomfort, diarrhoea, gas, bloating, and constipation. It’s important to note that these usually resolve quickly and on their own.

Immune Reactions

Again, it seems that what can be a health benefit can also be a side effect.

This time, it’s about the immune system.

There have been some links, in rare cases, of probiotics triggering individuals' weakened immune systems (5) or critical illnesses.

Examples of this are allergic reactions, septicemia and other infections. While very uncommon, they are still recorded among a very small number of people—so it’s a human health barrier worth knowing about.

SmartFact: The risk here is higher for vulnerable people such as critically ill patients, and premature infants. 

The right strain

That’s right. Not all probiotics are the same, and their level of safety varies.

When you are choosing a probiotic supplement, it’s really important to consider the strain used. Don’t just assume it’s OK for you—do your research.

SmartTip: To get the most from your probiotic supplementation efforts (and stay safe), check up on the dosage, the specific strain, and the manufacturing processes of the company— then make your decision.

Oh, and one more thing.

You might have noticed us saying “potential health benefits" and “potential side effects”.

While there’s growing evidence suggesting that a healthy gut microbiome is associated with various health benefits (including Improved digestion, immune function, and mental well-being), we should note that a lot of the studies are really in the early stages, and more research is needed before the true complexities of the gut microbiome and its impact on health.

Plus, much of this relates to individual experience—and correlation does not always imply causation.

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Doesn’t the human body have probiotics inside it?

While it is true that the human gut contains trillions of microorganisms, including beneficial bacteria that play a crucial role in digestion, immunity, and overall health, the amount and diversity of these microorganisms really varies from person to person.

But, it isn’t clear whether these factors alone can ensure that an individual has the right amount of probiotics in their gut without supplementation.

As we’ve said, the efficiency and safety of probiotic supplements depend on the strain and dose of the bacteria.

In summary, although the human gut is home to a complex microbial ecosystem, there’s no one-size-fits-all answer to whether we have the right amount of probiotics in us without supplements.

The optimal amount and balance of gut bacteria may vary among individuals and depend on multiple factors. 

Are probiotics safe?

While probiotics are generally totally safe for consumption—and even provide a host of health benefits when using the right strain and the correct dosage—a small number of people do experience side effects ranging from mild to severe. 

Check with your doctor before deciding to take probiotics, especially for those with specific health conditions or compromised immune systems.

More research is needed to establish the safety and effectiveness of probiotics in specific populations (8). Ongoing studies are taking place to explore both health benefits and potential risks. 

Can I use probiotics when pregnant?

Yes, probiotics are considered safe for pregnant women. But, always talk to your doctor before starting probiotics or any supplements first. 

There are some studies that suggest probiotics taken during pregnancy may help ease symptoms of gastrointestinal issues and even support both a mother’s and infant’s health.

That said, the specific strains, dosage, and duration of probiotic use may vary—so it is important to consult with your healthcare provider for personalised advice— as we always say.

They can consider your specific health needs and recommend just the right probiotic supplement for you and your specific pregnancy. 

Make sure you always choose reputable probiotic products from reliable sources and brands.

Choose probiotics that provide specific information on colony-forming units and strain-specific information on them. So you’re fully informed.

Which foods are best for probiotics?

Some foods are high in probiotics and can be consumed as a way of maintaining good gut health.

These are the most common:


This is one of the most well-known and easily accessible sources of probiotics. Yoghurt types that contain live and active cultures, like Lactobacillus acidophilus and Bifidobacterium lactis are ideal.


Similar to yoghurt, this fermented milk drink has a bit of a thinner consistency. It contains probiotic bacteria. 


This fermented cabbage dish can be bought in a jar. It has various beneficial bacteria like bifidobacterium lactis and lactobacillus acidophilus.


A famous Korean dish made from fermented veg like cabbage, scallions and radishes. It contains beneficial bacteria and is a good source of probiotics.


This is a fermented soybean paste that is commonly used in Japanese cooking. It contains a treasure trove of beneficial bacteria. 


Perhaps a lesser-known food used frequently in vegan cooking, tempeh is a fermented soybean product which is like tofu, but firmer.

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This is a fermented tea drink that has both yeast and beneficial bacteria. Sometimes it’s flavoured to make it extra appealing to the tastebuds.

Are all probiotics the same?

All probiotics are not the same.

They come in different species of live bacteria and also in different strains of probiotics.

Every strain has bespoke properties that do different things to human help. How well probiotics work depends on the dosage, the strain, and the health condition of the individual. 

Some probiotic strains have been shown to have specific health benefits. For example, Lactobacillus rhamnosus GG has been shown to reduce diarrhoea and digestive symptoms.

Bifidobacterium lactis Bb-12 has been associated with improving immune response. So, by choosing probiotics studied for a specific health condition, you can match the probiotics to a specific health condition.

Whether to take a probiotic, which strain(s) to choose, and the optimal dosage can depend on individual circumstances. Have a talk with your doctor to confirm which would be beneficial to you.

How to Use Probiotics Safely

In the UK, the regulation of probiotics is overseen by several entities. 

The Medicines and Healthcare Products Regulatory Agency (MHRA) is one such regulatory body that ensures the safety, quality, and efficacy of probiotics marketed as medicinal products.

Plus, the Food Standards Agency (FSA) and the Department for Environment, Food and Rural Affairs (DEFRA) are responsible for regulating probiotics marketed as food supplements (9).

Along with the Department of Health and Social Care (DHSC), these are the regulatory bodies that manage the laws and regulations of food supplements in the UK.

The regulation of probiotics in the UK can also involve other bodies and legislation, depending on the specific claims and intended use of the product. 

For example, claims made in advertising for probiotics are subject to scrutiny by the Advertising Standards Authority (ASA) (10) and may also need to align with the guidelines of the Department of Health and Social Care and the European Commission.

All these bodies work together to ensure the quality, safety and compliance of all probiotic products that are released into the UK market.

It’s worth noting that although there are many potential health benefits to probiotics, there are no authorised health claims for probiotics in the UK and EU.

These are associated benefits and can be referred to in scientific literature.

The US

In the US, the regulation of probiotics is overseen by one main body.

They are regulated in the US by FDA's Center for Food Safety and Applied Nutrition. Depending on a probiotic product's intended use, the FDA might regulate it as a drug or a food ingredient. 

Unlike drug companies, makers of probiotic supplements don't have to show their products are safe or that they work, which means it’s really important to do your research on the companies manufacturing the products.

How do I use probiotics to hit my health goals?

Probiotics have been shown to have various health benefits and can help individuals achieve specific health goals.

We know that they may be able to assist with helping your immune system, mental health and gut health. But, did you know? They can also help with weight management.

Probiotics may help to affect body weight by improving the gut microbiota. Strains such as Lactobacillus gasseri are said to aid in reducing belly fat and systemic inflammation in overweight individuals.

That said, probiotics are not one-size-fits-all, and how effective a specific strain is depends on lots of different things. The main factors include underlying medical conditions, age, and general health status.

Can children have probiotics?

Yes, children can have probiotics but talk to a doctor first before giving them supplements.

It’s generally advised for children to get their probiotics from food rather than from probiotic supplements. 

Probiotic supplements have an 18-plus label on them to communicate that they are only intended for adults.

There is only limited safety data when it comes to infants, so it isn’t advisable to give probiotics to them in supplement form, rather than with food.

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Do athletes take probiotic supplements?

Athletes do take probiotics for various reasons. 

As we know, probiotics have been linked to improved digestion, gut health, and immune function—which are pretty much essential for athletes looking to push themselves ahead of the pack.

They need their bodies to be in peak physical performance and to have optimum overall health.

Probiotics can potentially enhance the recovery of athletes post-exercise and reduce the risk of infections and possibly inflammation they incur through training. 

There have been some studies that suggest athletes and non-athletes who supplement with probiotics fatigue later than without.

How to read probiotic labels

To read probiotic labels, it’s important to look for specific information that can help you evaluate the product's quality and effectiveness.

When examining a probiotic label, here are some key factors to consider:

Genus, species, and strain designation

Look for the specific names of the probiotic strains included in the product. 

Knowing the strains can help you determine if they match with the probiotic strains that have been studied and shown beneficial effects in scientific research.

Colony Forming Units (CFUs)

CFUs indicate the number of viable organisms in each dose or serving of the probiotic product. Look for the CFU count on the label to understand the potency of the product (11).

Expiration date

Check the expiration date to ensure the probiotics are still viable and effective until that date.

Expired probiotics aren’t going to work as well as they should.

Additional ingredients and potential allergens.

Pay attention to any additional ingredients or potential allergens listed on the label. Very important for those who have allergies or dietary restrictions.  

Reading probiotic labels can provide important information about the strains, potency, and quality of the product. 

But, it's important to note that the label alone may not provide a complete understanding of the effectiveness of the probiotic. 

Remember, interpreting probiotic labels can be complex, and we always recommend consulting with a healthcare professional or a registered dietitian if you have specific questions or concerns.

Should you take probiotics?

Whether or not to take probiotics depends on individual factors and health goals.

Want support with losing weight? Help to strengthen your immune system? Improve your digestion?

Specific strains of probiotics could be for you.

Of course, we always need to bear in mind factors such as overall health, specific health conditions, and individual needs.

Also, it's important to consider the potential side effects and risks associated with taking probiotics, especially in individuals with compromised immune systems or underlying health conditions. 

Just to drive the message home: It’s crucial to consult with a healthcare professional to determine if probiotics are appropriate and safe for your specific situation.

What makes Smart Protein different?

Our Smart products are specially formulated to target specific wellness and fitness goals.

As standard, they have…

  • No added sugar
  • No artificial colours
  • Natural flavourings
  • Highest quality ingredients
  • Gluten-free
  • Soya free

But, it isn’t just those reasons we’re different…

Why try Smart Protein probiotic gummies?

Our delicious Smart Protein Boost & Balance Apple Cider Vinegar Gummies give you a whole body boost.

Designed to support the psychological functions you need to feel on top of life, each gummy has 1000mg of apple cider vinegar, beetroot, and pomegranate juice to aid weight-loss management.

What makes ours special is that the gummies have 2.25 Billion CFU of good bacteria in each serving which is a large amount compared to competitors. 

They also contain a healthy blend of Vitamins C, B3, B5, and B6 which other brands don’t always include.

Oh, they’re also safe for gluten-free individuals and vegetarians. 

Our gummies also come loaded with B12 to promote immune support and make sure your metabolism is burning away as it should.

Two gummies a day is the best way to maintain blood cell formation, reduce fatigue, and help support your energy levels, all thanks to the probiotics within.

So go with a safety-conscious, high-quality probiotic blend if you want to help support your gut health and overall health all in one.


Smart Protein is committed to sourcing only the best and scientifically-backed research in our articles.



2. Medical News Today:


3. Ncbi:


4. Pub Med:


5. Pub Med:


6. Cleveland Clinic:


7. Cell Press:


8. Healthline:


9. HSIS:


10. ASA:


11. ODS:


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