Here is your question today: True or False: When you take a probiotic, the goal is to literally plant new flora in your gut and help your current flora grow more.

It is commonly suggested that probiotics must stick and multiply in the gut to be effective. This isn’t how our current probiotic supplements work. A number of studies have shown that probiotics do not become established members of your gut ecosystem and when you stop taking them, their numbers dwindle quickly.

You could take probiotics day after day, year after year and if you stop, you will see that specific probiotic strain level decline and disappear. This usually occurs in 2-6 weeks. We can detect the probiotic that you are taking, when you are taking it, but the native colonies will remain mostly unaffected.

Here’s why, I am sure that you have heard of the probiotic lactobacillus. Within the Lactobacillus genus, there are over 180 known species of lactobacillus. L. acidophilus is a common one, along with L. casei, L. brevis, to name a few. Within each of these species, take L. acidophilus for example, there are many, many different strains.

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Your native gut flora, the flora that has been present since birth, is strain specific. You may notice on your probiotic bottle, that L. Acidophilus has a number after it. It may read L. acidophilus LA1 or it may read L. acidophilus DDS-1. This means that this is the LA1 strain or the DDS-1 strain of L. acidophilus.

Seattle Nutritionist Probiotics Boost Immune System

The only way to directly influence the level of your specific strain of gut flora is to take the same exact strain probiotic – L. acidophilus (insert your STRAIN). The problem is that we are not yet able to test your specific strain and customize a probiotic blend that is specific to your native gut flora. We are simply not there yet, but this is what is coming and WHAT a game changer it will be. When we are able to offer the exact strains of your native gut flora in a probiotic, this is going to going to be a magic pill.

Let’s talk further about strains and how vastly different they are. Even though all L. acidophilus strains are of the same species – they are all L. acidophilus, they are all different strains, with vastly different properties. Think about all the different types of dogs there are out there. Consider these strains. Consider a Chihuahua and a Great Dane different strains of the same species Canis Lupis. Think about how different these dogs are. Think about how different a Corgi is, or a German Shepherd.

Are taking probiotics a good idea? YES – an enthusiastic YES!

Probiotics have been shown time and time again to have a positive effect on health. Here’s how they do work – they help to regulate your immune system. We call this an immunoregulatory effect. They help to tune and regulate the immune system by interacting with immune cells in the gut. They literally cross talk with immune system cells in your intestinal mucosal layer. By doing this, they teach the immune system to calm down and to be less reactive.

Probiotics are active cultures. These are alive. In studies we have seen dead probiotics, with no biological activity, still have a positive effect on health. The DNA of the probiotic is still cross talking with the immune system. This occurs when immune cells sample the probiotic by engulfing it in the GI tract.

Here are some guidelines for choosing a good probiotic:

When taking probiotics, a larger dose does not mean a better affect. When you look at two bottles and you see one has a million colony forming units and the other bottle has a billion colony forming units, the bottle that has a billion is not better. The better probiotic is the one that contains the strain that has been shown in studies to be effective.

You want your bottle to list out the strains. I don’t want to see L. acidophilus on the label. I want to see L. acidophilus LA1 (or another strain listed, so I know what strain I am taking).

I also recommend pharmaceutical line probiotics and NOT direct to consumer lines. Direct to consume lines do not often contain the label ingredients, nor do they come close to containing the listed label dose per serving. These are manufactured to be at label dose at the time of manufacture, and not the time that you take them. Pharmaceutical line probiotics are guaranteed at label dose when you take them. They manufacture these at higher than label dose, compensating for die off of active cultures while sitting on the shelf or at home.

Single strain probiotics have been shown to be effective. Multi-strain probiotics have been shown to be effective. Multi-strain probiotics are not better than single strain probiotics. We need to look to the studies to see which strains have been studied and shown to be effective and use these. This is why the probiotic bottle MUST list the strain, otherwise they don’t even know what is in it.

Angela Pifer, Creator of the Clean & Lean Revolution

Seattle Nutritionist – Work with Angela one on one

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from 5 people


Hi Peter,

I list out most of the probiotics that I use on my website. I also use GI ProHealth's GI Prostart to make my homemade yogurt. Hope this helps!




I use a blend of 15 Probiotic from a supplier which does wonders for making a great tasting yogurt but they don't list the strains. They sell a blend of 4 flora with the strains cited. I've used both for yogurt. What would be best or flop to new strains every 3-4 months? Where do I find a list of good strains as you mentioned? Thanks!

Peter Zlo


Great information! You answered my question of why you need to take probiotics repeatedly. I figured that if these bacteria multipled in my intestins then I should only need to reinforce them once in a while. I had conducted an extensive web search and could find no other answer that made sense.

Learned the probiotics specific strain would have to match those native to my gut - which appears to be a low probability.



Ed A


GREAT question - I recommend probiotics to be rotated on and off, long term. Though the specific strain doesn't stick around, probiotics do evoke a lot of change. They cross talk with our immune system and help it calm down and be less reactive, they support our colonies - think of these as a GI function boost/ immune boost. Rotate the strains you are using every three months and take a few months off a year (this is maintenance).




Thank You Angela for the insight.
Even if one were to take a pharmaceutical line probiotics with strains that have been studied and shown to be effective - does it need to be taken forever? Because as you said - once you stop, you will see that specific probiotic strain level decline and disappear?

Thank You


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