The gut microbiota is a complex ecosystem that needs to be balanced and healthy for optimum health.

Probiotics can help your gut microbiome and you. Therefore, a better understanding of how the impact of probiotics on colonizing microbiota of the gut affects us requires more insight and research in order for you to derive benefit from any probiotic supplementation.

The World Health Organization (WHO) has probiotic guidelines that show how easy it is to integrate these beneficial bacteria into our diets, which will not only improve the health of our intestines but also reduce the risk for cardiovascular disease and diabetes.

When we eat them or take a supplement form, they colonize in all parts of the digestive tract including the mouth, esophagus, stomach, and small intestine.

They produce enzymes that digest food particles so more nutrients are absorbed by the body and synthesize vitamins such as B12 and K2.

Probiotics Don’t Colonize Well

However, not all probiotics will naturally colonize the human intestinal tract.

When we talk about colonization we mean that at least 1 billion of the probiotic cells must be present and alive in the intestines throughout the day to help support health and prevent disease.

So if you were to take a probiotic supplement that has never been tested against a placebo or another strain and you don’t see any benefits it probably means that the strains in your supplement can’t colonize or that it doesn’t contain enough cells to help support health.

This is why we need to know if a probiotic strain has been tested against a placebo and/or another strain—we want to ensure that there are enough live cells present in the intestines that will be able to colonize.

Probiotics may have No Health Benefits

It is also important to know what each strain can do because it can often get over complicated.

For example, if you are trying to reduce bloating and abdominal pain associated with IBS you would want to take a probiotic supplement that contains the strain B.infantis but not all probiotics work for everyone and every health issue you’re trying to target.

If we continue with the example above, if you were to take a probiotic supplement that contains B.infantis and it doesn’t reduce your bloating and abdominal pain then it could be because:

1) The strain B.infantis works for reducing bloating and abdominal pain associated with IBS but you take the supplement at the wrong time (i.e., not during or right before your symptoms).

2) You don’t produce enough of the metabolites that B.infantis creates through fermentation in your intestines to help reduce bloating and abdominal pain associated with IBS.

3) You don’t produce enough short-chain fatty acids (SCFAs) in your intestines to help reduce bloating and abdominal pain associated with IBS. This is possible if you have too much of a different strain that produces gut flora imbalances and disrupts the production of SCFAs. Or you may not be producing enough SCFAs in general.

4) You don’t absorb the metabolites that B.infantis produces through fermentation in your intestines well enough to help reduce bloating and abdominal pain associated with IBS (i.e., you’re not absorbing short-chain fatty acids [SCFAs]). This is possible if you have too much of a different strain that produces gut flora imbalances and disrupts the absorption of SCFAs. Or you may not be absorbing enough SCFAs in general.

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Probiotics and microbiome are being used to treat diabetes and obesity

Probiotics are Difficult to Prescribe

It can also get really complicated when many strains work together to promote health because each strain produces metabolites that the other does not, so it is possible for you to have a gut flora imbalance or be unable to absorb metabolites produced by certain strains.

Probiotics Don’t Survive in the Intestines Long Enough

Another common problem with probiotic supplements is that they don’t contain enough live cells (i.e., they are underdosed) to colonize the intestinal tract.

If you take a probiotic that is underdosed then it will pass through your intestines without being able to have an effect on your health and well-being.

Probiotics are Ineffective due to Acid Tolerance Testing (ATP)

The problem with how most companies determine the potency of their probiotic supplements is that they have been tested against a placebo, which means that they use what is called ATP (assay for the total bacterial count) “survival testing” to determine if a strain can colonize in the intestines.

So it’s not actually being tested against a placebo and this method doesn’t take into consideration that all probiotics are different.

As a result, companies only look at the number of colony-forming units (CFUs) instead of looking into how well each strain can adhere to the intestines or whether they produce enough metabolites to colonize in the intestines.

Probiotics are Difficult to Test for Colonization

If you do not see the strain(s) listed on the label of your probiotic supplement, then they may have tested it using ATP (assay for the total bacterial count) “survival testing” and if that is the case it is very likely that the strain would not survive in the intestines.

ATP testing is a standard method of determining the potency of probiotics, but it doesn’t take into consideration that all probiotic strains behave differently and produce different metabolites.

It also doesn’t take into consideration whether the strain is able to adhere to the intestines and colonize, so if you are taking a product with a placebo probiotic content then there’s nothing for your body to act on.

This method is just an assay for the total bacterial count that tells you how many live bacteria will survive in the supplement, not whether they can colonize in your intestines.

It doesn’t take into consideration if they produce metabolites that are effective, so it doesn’t tell you how much benefit each strain can have for your health.

What is the Best Way to Test for Colonization?

To find out what you’re dealing with, you would need to test whether a given probiotic strain is able to colonize in the intestinal tract by culturing them on special media that mimics your intestines or mucus layer and then looking at whether the strain is able to attach itself.

The reason we need to look into adhesion, as well as colonization, is that not all strains are equally equipped to colonize in the intestines, even if they do produce metabolites like SCFAs.

If a strain cannot colonize or adhere to your intestinal wall, then those metabolites will be lost to your intestinal contents and you won’t get the full benefits of the probiotic strain.

Differences between Species, Strains, Cultures, & Subcultures

There are several different types of bacteria that all fall under the term “probiotics”. The most common type is Lactobacillus and Bifidobacterium.

There are over 400 species within these two different genera which can be further divided into strains and sub-cultures to make them unique from one another.

These different types will have differing effects on the human body and they may not all live up to their health claims.

For example, a strain of Lactobacillus acidophilus may have different effects on the body when compared to a strain of Lactobacillus rhamnosus.

As well, there are both single-species probiotics and multi-species probiotics available on the market.

Both types can be beneficial to the human body but the benefits will depend on how many different strains and how much of each strain is contained in the probiotic supplement.

In conclusion

Probiotic supplementation can help colonize the gut with more beneficial bacteria and reduce the abundance of potentially harmful bacteria in humans, thereby improving overall gastrointestinal health. 

Other studies have also shown benefits from probiotics such as maintaining normal levels of good bacteria, reducing inflammation in the intestines, lowering cholesterol levels, and even reducing colorectal cancer risk.

For these reasons, it is important to read labels carefully when selecting foods or supplements containing probiotics.

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