Lactobacillus casei (L. casei) is a probiotic bacterium that has undergone classification changes over the years. The probiotic listed on your supplement may not actually be L. casei.
For most people, this won’t matter, but for those who have read unfavorable things about L. casei, such as histamine production, please continue reading. A lot of websites publishing information about probiotics may not delve into the studies to know the differences, so they unknowingly are passing on incorrect information to you. My goal for this website is to base the information on science, so I read through the tedious details as best I can.
If you haven’t read the page on Lactobacillus yet, I encourage you to do that so you can understand the subtleties of the Lactobacillus genus.
are Gram-positive, non-spore forming, lactic-acid producing, rod-shaped
bacteria which do not have flagella to move about. They are commonly
found in the gastrointestinal (GI) tract, fermented vegetables, milk,
meat, silage and sewage. They are often used as promoters of maturation
of certain cheeses and may possibly be found in therapeutic amounts in
some cheeses or dry-fermented sausages. This species has QPS (Qualified
Presumption of Safety) in the European Union.
As you might expect, the type strain had its origin in a dairy product (cheese) and thus the name casei, from casein.
Like many other microbes, L. casei strains are subject to genetic engineering, especially for oral or intranasal vaccine antigen delivery.
What happened to L. casei is similar to what happened to L. acidophilus. There is an L. casei group and then an L. casei species. The group contains the species L. casei as well as L. paracasei and L. rhamnosus. While the species in the group have similar characteristics, they are different enough to validate having their own species.
The type strain for L. casei is ATCC 393. This is the strain to which all other microbes are compared to see if they genetically qualify as Lactobacillus casei or some other species. It appears that the ATCC 393 type strain is different compared to most other casei and paracasei strains and appears to be related to L. zeae. As a result, the taxonomic status of these species and identification of strains in these species are still being debated.
Over the years, the differences found between L. casei and L. paracasei led some researchers tried to establish the type strain of L. paracasei (ATCC 334) as the type strain of L. casei and true L. casei ATCC 393 as L. zeae. Thankfully for us, there is a ruling body for matters like this, and the Judicial Commission of the International Committee on Systematics of Bacteria ruled in 2008 that ATCC 393 is in fact the type strain for Lactobacillus casei and Lactobacillus paracasei is another species.
What this means to you as a consumer is that many casei were/are in fact paracasei, but scientists and manufacturers did not want to officially change the names of their strains for 2 reasons: one, because they were established as casei ; and, two, because this subject is still being debated. Unfortunately, doing so makes it extremely harder to follow the trail of research to know exactly which species a microbe belongs in. It also means that when you hear unfavorable news about the L. casei species, you don’t know if that news applies to the supplement you are taking or not. Likewise, if you hear good things about paracasei, you don’t know if that applies to the “L. casei” in your supplement.
Since many probiotic supplements have proprietary formulas, many manufacturers are not willing to say (or do not know) if their L. casei is the real thing or not. I hope to clear up some confusion about this issue through this website.
As always, the best thing to do when choosing a probiotic is to know information about the strain.
If you’ve been following this website or my newsletters at all, you know that probiotic actions are strain-specific. However, there are some general characteristics about L. casei , based on the type strain, that make it what it is. In addition to the information presented above, the ATCC 393 type strain:
Ah, the big question: Does L. casei produce histamine or not? The answer is a definitive, "It depends." As a species, Lactobacillus casei may or may not produce biogenic amines like histamine and tyramine.
L. casei has a bad reputation of being dangerous for people with histamine intolerance. However, the ATCC 393 strain was found to NOT produce tyramine when exposed to tyrosine and some strains actually degrade the biogenic amines in vitro. Again, the strain is important!
Some of the strains currently labeled on products as "casei" that I will be building pages about are:
Return to Lactobacillus page.
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