Autism: What Is L. Plantarum?

Lactobacillus plantarum WCFS1  is a particular strain of Lactobacillus plantarum, and it is one of the best-studied Lactobacilli. Its genome was reported in 2003 and currently, only 30% of gene function is unknown.

Whereas I’m sure everybody’s heard of L. acidophilus NCFM2 and L. rhamnosus GG3 – those two bacteria, the genomes were only reported in 2005 and 2009 respectively.

There are actually 26 genome sequences of different L. plantarum strains available in the NCBI database. 

L. plantarum Availability

I’m sure everyone is curious as to if you take L. plantarum, what exactly happens in your body?

A study was done on L. plantarum NCIMB 8826 (the parental strain of L. plantarum WCFS1) and it shows a high survival capacity in the human GI tract. After a single oral dose of 1.5 x 1010 CFU, the survival of L. plantarum NCIMB 8826 was, was 7%. 

So if you’re thinking about taking a probiotic, not all of it is gonna survive your GI tract, and this was measured in the ileum (which is the end of your small intestine) in 18 healthy individuals in France.

That study continued for seven days, so over seven days, individuals took L. plantarum NCIMB 8826 orally, and then they also measured the fecal survival rate, and they found that to be 25 +/-29%. 

This wasn’t a huge study. It wasn’t a large clinical trial. Again, this was looking at healthy individuals and they just wanted to really understand the survivability of L. plantarum, NCIMB 8826.

There were two other bacteria that were examined in this study, and they looked at L. fermentum KLD and Lactococcus lactis MG 1363, and the ileal survival was only 0.5% and 1% respectively. 

Survival rates really depend on the actual bacteria and also the strain. None of the strains colonized the intestinal tract of these three that were studied. However, bacteria colonizing the epithelial surface were not studied. And this work was done actually to explore L. plantarum NCIMB 8826 as a possible oral vaccine vehicle. 

If you’re familiar with L. plantarum, you might be familiar with the strings 299 and 299v and if you are, you know that these strains of L. plantarum can colonize in the gut for long periods of time. So again, there’s variability within the strains of even the same bacteria as to whether or not they colonize in the gut or not. L. plantarum 299v is a very popular commercially available probiotic.

L. plantarum Clinically Studied​

The 299v strain reduces in vitro expression of pro-inflammatory genes in a cultured model of colonic mucosa. L. plantarum has been shown to have anti H pylori activity, and that’s super important because many of the children with autism also have an abundance of H pylori in their stomach. 

L. plantarum  has been shown to improve the symptoms of irritable bowel syndrome and a clinical study that used 200 patients. So that was a significant number there. L. plantarum Lp91 showed strong immunoregulatory capacity in a murine colitis model.

L. plantarum Mechanism Of Action

The mechanism of action, exactly how L. plantarum interacts with the host (us) is still not fully understood. 

L. plantarum is known to produce bacteriocins, which are antimicrobial peptides that kill other bacteria. Pore formation, which is basically when the cytoplasm membrane gets disrupted, is one of those potential mechanisms of the bacteriocins. Bacteriocins promote a bacteriocidal effect with or without cell lysis inhibiting cell growth. 

L. plantarum is very well known for producing, we call it metabolites, producing peptides are bacteria that kill other bacteria. So you can think of L. plantarum along the lines of an antibiotic, but one that is a natural one.

L. plantarum Safety

So the US FDA is reviewing the safety of  299v and will likely give it the GRAS (generally recognized as safe) notation. 

L. plantarum And Autism

In 2010 results from a double-blind placebo-controlled crossover study involving the oral administration of L. plantarum WCFS1 to children with autism were published. This study found a significant increase in lactobacilli/enterococci and reduced Clostridium cluster compared to placebo. 

So there definitely was a change in the gut microbiota compared to placebo. It also effectively improved stool consistency and decreased overall behavior scores. And remember, the study was done in children with autism.