Flu Viruses- Postbiotic Research

Influenza A

In Y.J. Jung et al (2019) researchers find “Heat killed Lactobacillus Casei confers broad spectrum protection against influenza A”.  Note: The term heat killed L. casei means the researchers have destroyed all live L. Casei probiotics.  Translation: they’re relying 100% on an isolated compound (a postbiotic) which is internal to the L Casei or its cell wall. The postbiotic was created from fermented vegetables, isolated with centrifusion, and named DK128. In order to produce results, the test mice had to be “pretreated” or fed with DK 128 for a number of days prior to infecting them with a lethal dose of Influenza A.  This conferred the broad immunity.

Here we quote: “The results correlated with an increase in alveolar macrophage cells in the lungs and airways, early induction of virus specific antibodies, reduced levels of pro-inflammatory cytokines and innate immune cells. Importantly the mice were protected against primary viral infection as a result of heat killed DK128 Pretreatment and developed hetersubtypic immunity against secondary virus infection.”  The study also comment that  the untreated mice were ineffective at producing antibodies at an earlier time post infection. This resulted in higher viral replication, severe weight loss, and death in 100% of the untreated mice.

Conversely, the pretreated mice had earlier induction of IgG antibodies that controlled viral replication in the earlier stages of infection which produced 100% survival rate against lethal influenza A strains with little or no weight loss in test animals. This study is the first to identify a postbiotic of any good bacteria which produced 100% survival in test animals. Other studies involving different probiotic bacteria and the same fermented foods had provided flu benefits which were more modest. Ie: increased survival rates like 30%, or reduced incidents of getting the flu, or reduced flu duration/severity, etc.  However,  the majority of test animals still died and many those that survived often experienced severe weight loss.  This study and others like S. De Marco et al (2019) show not all probiotics are equal when it comes to making postbiotics which get results.  

Additionally the probiotics which do produce benefits often require specific phytonutrients in plants as essential ingredients to produce the desired postbiotic benefit. For example, another flu study by Ashley L. Steed et al  ( 2017) identified the flu fighting postbiotic desaminotyrosine (DAT for short) was created from plant flavonoids.  Diet is a determining factor. No plant flavonoid = no DAT. Not all probiotics are equal when it comes to making an effective postbiotic with the benefits researchers are seeking.  As demonstrated above, they typically need a combination involving a specific probiotic plus a specific plant nutrient. (Also see: “Important Pre/ Pro/Postbiotic Considerations” to understand other important matters that lead to benefits vs poor results).

Premature babies lack the mature microbiomes adults and older children have but L Rhamnusus is known for its ability to colonize in newborn babies. Interestingly at one time L rhamnusus had been classified as L casei due to their similarities.  However at some point L. Rhamnusus was listed as a species in its own right. American researchers in Ogan Kumova et al (Oct 2019) voice that premature neonatal babies are especially vulnerable to influenza infection with higher mortality rates, and they wondered if L Rhamnusus might prove beneficial. Their study used test animals pretreated with an intranasal spray of L. Rhamunsus and they found it dramatically improved protection and survival against Influenza A.