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This month a number of persons asked me about the probiotic Lactococcus lactis (in Probiorinse) and whether it works. This product is marketed to people with sinusitis or sinus infections, with the message that it improves the sinus microbiome and sinus health. Does it?

Unfortunately, no. A well-done study published last year found that the bacteria Lactococcus lactis (Probiorinse) doesn't help to improve sinus symptoms in those with sinus issues. Yes, that bacteria is found in the sinuses, but it is not a keystone bacteria (one with a big effect) in sinus health.

The study compared the Probiorinse (Lactococcus lactis) product to Xlear (xylitol) and regular saline rinses.

The researchers tested xylitol, the probiotic Lactococcus lactisand ordinary saline rinses separately for one month in a group of persons with chronic sinusitis. They found that none of these improved sinusitis symptoms or sinus microbial diversity (the sinus microbiome). In other words, there were no significant differences among the 3 groups.

Those with chronic sinus problems still had them at the end of the study, and their sinus microbiomes and symptoms were still very different from those of the healthy participants.

By the way, another study analyzed Lactoccocus lactis (using the product Probiorinse) against some strains of harmful bacteria (Pseudomonas aeruginosa) collected from persons with chronic sinusitis and found "no effect on 4 strains, a modest inhibitory effect on one strain, and a modest proliferative effect on one" (it increased this harmful strain!). Basically no effect - not a good result.

Bottom line: Don't bother buying the 2 products and stick with ordinary saline rinses. The medical view is that saline nasal irrigation is recommended because it helps a little with nasal stuffiness or congestion, even though this effect is temporary (a few hours?). Can also try the probiotic Lactobacillus sakei, which is a keystone bacteria in the sinuses and which kills/dominates over many harmful bacteria.

Excerpt from the 2021 study by Lambert PA, et al., in the medical journal  Laryngoscope Investigative Otolaryngology:  Microbiomics of irrigation with xylitol or Lactococcus lactis in chronic rhinosinusitis

No significant trends in alpha or beta diversity as a result of treatment were observed. SNOT‐22 score did not change significantly following treatment with xylitol, L. lactis, or saline. [Translation: the microbiome (alpha and beta diversity) didn't change, and symptoms (SNOT-22 score) didn't change]

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According to a recent study, two commonly available treatments for chronic sinusitis don't work. Researchers tested xylitol, the probiotic Lactococcus lactis, and ordinary saline rinses separately for one month in a group of persons with chronic sinusitis. They found that none of these improved sinusitis symptoms or sinus microbial diversity (the sinus microbiome).

Interestingly, studies find that Lactococcus lactis occurs naturally in the sinuses of some people, yet in the study it didn't seem to have healing properties (in other words, not a keystone bacteria in sinus health). The finding of xylitol not helping with sinusitis symptoms is what most people have reported to me for years - so not a surprising finding.

Plain saline rinses may temporarily improve breathing, and are especially helpful when suffering from allergies, but it has long been known that they don't treat sinusitis.

The University of Rochester Medical Center researchers had study participants doing 1 treatment (either L. lactis or xylitol nasal rinse) for 1 month, then 1 month of saline rinse alone (the "wash-out" period), and then 1 month of the other treatment rinse. So each person tried all 3 methods. Their symptoms were assessed 4 different times with the SNOT-22 symptom questionnaire [some SNOT-22 problems]. 25 persons with chronic sinusitis (and a past history of sinus surgery) were enrolled, and 10 healthy controls (no chronic sinusitis).

So what should one try if suffering from sinusitis? Try  Lactobacillus sakei (it has helped many because it is a keystone bacteria, and also kills/dominates over many harmful bacteria). However, use it only when needed (when sinusitis symptoms start to appear) and stop when feeling better.

A month of using any product, as described in this xylitol and L. lactis study, may also be too long. One month could even lead to a sinus "imbalance".

For example, a few days or 1 week of L. sakei (whether kimchi or Lanto Sinus) may be enough! No need to repeatedly flood the sinuses with 1 product - normally healthy sinuses contain multitudes of species living in balance. ...continue reading "Some Treatments Don’t Work For Sinusitis"

Shucks... A randomized controlled trial (the best kind of study) found that probiotics and xylitol did NOT help sore throat symptoms. Sore throats are medically known as pharyngitis. Xylitol is a birch sugar that causes local “bacterial interference” by inhibiting bacterial growth and the adherence of bacteria to the pharyngeal wall (the throat). The probiotics (beneficial bacteria) that they tested were strains of  Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium animalis. They also tested sorbitol chewing gum, which does not have any antiviral or antibacterial properties. Not one of these alone or combined had any effect on sore throat symptoms.

My take on this: perhaps other species of probiotics might help - maybe yes, maybe no. Just testing 3 strains of bacteria is too soon to rule out probiotics. This view is based on our (and others) experiences with chronic sinusitis - that it takes very specific bacteria species (especially Lactobacillus sakei) to treat sinusitis, and just taking some random strains may not help at all. From Science Daily:

New RCT shows no benefit from probiotics, xylitol chewing gum in alleviating sore throats

The use of probiotics and xylitol chewing gum to alleviate sore throat symptoms -- as an alternative to antibiotics -- appears to have no effect, according to a randomized controlled trial (RCT) published in CMAJ (Canadian Medical Association Journal).

Evidence exists that indicates probiotics and xylitol, a birch sugar that prevents bacterial growth, can help reduce recurrence of upper respiratory tract infections.

The study included 934 people in the UK during the four year study period (June 2010 to 2014), of whom 689 provided complete data for the trial. Using a symptom diary, participants reported the number of probiotic capsules and sticks of chewing gum used each day, as well as the severity of symptoms. They were study "compliant" if they had taken 75% of their allotted treatment.

Researchers found no significant effect of either probiotics or xylitol on sore throat (pharyngitis) symptoms. "There were no significant differences between groups for both the xylitol and the probiotic groups, which suggests that neither intervention helped in controlling acute symptoms," the authors write. [Original study.]

 Sore throat. Credit: Wikipedia