If you are a health fashionista, the chances are that you have taken a probiotic at some point in the hope to improve your gut health and general well-being.
You might have indeed gotten some great benefits from it, or maybe not!
The truth is… there is a lot of confusion around probiotics — what they are, what they do, and which is best to consume to improve your health.
In this post, I will attempt to give you a clearer understanding of probiotics, as well as some helpful tips on how to best include them in your diet or supplement regimen.
DEFINITION…WHAT IS A PROBIOTIC?

A probiotic is a live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.
They can come from fermented foods (yoghurt, kimchi, sauerkraut) or from supplements containing freeze-dried bacteria.
MYTH BUSTING
First, let’s clear something up… probiotics do NOT recolonise the gut.
They might stay in your gut for a day or up to a few weeks, but they eventually end up in your poop. It’s important to understand that they will not become part of what is known as your microbiome.
So you can’t expect to wipe out your gut bacteria with antibiotics, and simply replenish them by taking a few capsules of probiotics, or by eating fermented foods.
Same thing is true of stool analysis (like ubiome, GI map, etc). You can’t simply replace what is missing (like lactobacilli or bifidobacteria) with a few probiotic supplements.
It’s just not that simple unfortunately…. I wish it were!
However, probiotics still have many health benefits, so let’s talk about how they actually work to improve your health.
HOW DO THEY WORK?
Here are some of the main benefits of probiotics:
1- Help to rebalance the gut bacteria by competing with potentially pathogenic bacteria and fungi along the gastro-intestinal tract for the limited space that is available. They also produce anti-microbial substances (like hydrogen peroxide) that can selectively kill off potentially pathogenic bugs and fungi . So in other words, they push away and/or kill the bad bugs, so that the good bacteria that are already in your gut can thrive and reproduce.
This is also helpful when taking antibiotics, as it can prevent the bad bugs from taking over.

2- Improve immunity by interacting with immune cells, potentially preventing you from getting yet another cold.
3- Produce beneficial compounds in the gut:
Short-chain fatty acids or SCFAs: These are very beneficial. They are used as energy by colonocytes. They have even been showed to improve brain health and reduce inflammation in the whole body.
Polyamines: Help restore a damaged small intestine and up-regulate intestinal brush border enzyme expression to help better digest your food.
4- Modify gastro-intestinal transit time: Can either speed it up (helpful for constipation) or slow it down (helpful for diarrhea).
5- Decrease visceral hyper-sensitivity:Â One of the contributing factors of IBS (irritable bowel syndrome).
6- Strengthen the intestinal barrier: Helps heal a leaky gut and inflamed mucosa.
![]()
Starting with small amounts and increasing slowly will help you avoid a potential ‘die off’ reaction which can happen when the bad bacteria are being pushed away.
Some people with very damaged gut flora have to start with very tiny amounts and slowly build up, over months or years.
NOT ALL PROBIOTICS HAVE THE SAME EFFECT
If you want to get the most out of taking a probiotic supplement, it’s important to understand the concept of strain specificity.
The human body has over 500 different probiotic strains, and they all have different roles to play to keep us healthy.
**When you take strong antibiotics, you kill a lot of those strains, and unfortunately, some of those never recover. This is why I recommend taking antibiotics only when absolutely necessary (life threatening infection). Read more about what else affects your gut bacteria here.
People get a bit confused between species and strains, and to get the most out of probiotic supplements, it’s important to understand the difference.
So here are a few species you might have heard off, which are common in probiotic supplements:
- Lactobacillus acidophilus
- Lactobacillus plantarum
- Lactobacillus rhamnosus
- Bifidobacterium bifidum
For each of those species, there are a lot of different strains, and the strain is what is important!
The strain is the number that is added at the end.
For instance: Lactobacillus plantarum 299v
** Every probiotic has a strain, but it is not always mentioned on the bottle which particular strain was used. I recommend avoiding those probiotic supplements as you don’t know what you are getting.
Different probiotic strains have different actions.
This is why certain probiotics might do wonders for someone, but do absolutely nothing for you… it just depends on your own gut ecosystem and body biology.
When researches are done on probiotics, they always use a specific strain.
Examples of well researched strains, and some of their benefits:
- Lactobacillus plantarum 299v: prevent C.difficile during antibiotic, reduce abdominal pain
- Lactobacillus rhamnosus GG: Reduce visceral hypersensitivity, reduce post-antibiotic diarrhea, C.difficile treatment, increase fecal bifido and lactobacilli (beneficial bacteria)
- Escherichia coli Nissle 1917: Reduce constipation
- Saccharomyces cerevisiae var boulardii Biocodex: Speed up healing of mucosa (may help heal a leaky gut)
So when choosing a probiotic supplement, make sure you know exactly what is in it!
SIBO AND PROBIOTICS
If you have SIBO, you might be scared of taking probiotics. However, certain strains of probiotics are very useful for SIBO treatment and can even help reduce methane production. They can also be helpful to correct motility issues. So as long as you take the right ones, you should get some benefits.
If you have SIBO, you might be interested in this post: 10 MUST DO TO BEAT SIBO

Opinion varies widely when it comes to fermented food vs probiotics supplements… which is best?
Personally, I like both… it depends on the desired effect and on the person’s symptoms and health history.
There is no doubt that fermented foods are great for many people and offer plenty of health benefits.
However, I do think it’s important to point out that fermented foods are not for everyone…
Learn more in this post: Fermented Foods… Is It For Everyone?
BENEFITS OF FERMENTED FOODS

Wide variety in the type of beneficial bacteria, compared to what you get in a supplement.
The process of fermentation makes the food easier to digest.
Fermented dairy: Increase B vitamins and free amino acids. If you are lactose intolerant, you can make lactose free yoghurt at home by fermenting for 24 hours (the process of fermentation eats up the lactose).
Sauerkraut/kimchi: Increase vitamin C, contains glucarate and Indole-3-carbinol (helps oestrogen metabolism), contains polyamines (may help to heal leaky gut). If you choose to buy sauerkraut, make sure it is raw. Most sauerkraut in the supermarket have been pasteurized, which removes all of the beneficial bacteria!
In general, when working with people who have gut health issues, I prefer to start with a probiotic supplement rather than fermented foods, as I’m usually after a very specific effect, which I know I can achieve with specific strains. However, once the gut is healthier, I like to slowly transition to using fermented foods (if tolerated) to keep improving the gut ecosystem.
For people without serious gut issues who are mainly looking to improve their general health, I would recommend consuming a variety of fermented foods. Example of fermented food: sauerkraut, kimchi, yoghurt, milk and water kefir, Kombucha, miso, tempeh, etc.


I have a question. You say these bacteria are transient and do not take up residence in the gut; this I know but I’m wondering about soil-based bacteria, all that is mentioned here are Lactobacilli/Bifidobacterium. Do other types just flush out as well in the end?
I took Prescript-assist for some time until they changed the formula and it contains completely different bacteria. Can you shed some light on this? 🙂
Best, Helen
Soil based do tend to stay longer in the gut, but they still don’t become part of your own community. It’s important to understand all the other roles that probiotics play though, as they do still greatly influence the population of bacteria in the gut. I just wanted to emphasize that it’s not as simple as taking a few pills after taking antibiotics to replenish the good bugs! Regarding soil based, I would recommend checking out RightBiotics Rx by Real Dose Nutrition… not as well known as other soil based, but it contains the best studied soil based bacteria in it. With probiotics, I find that it does help to try a few different types to see what works for you. If you don’t feel better after taking it for a few weeks/months, I recommend switching to another one. I hope that helps!
Thank you! Happy you cleared this up for me. 🙂 Will check out your recommendation.