When I last looked at Miyarisan, it was available in Japan only. In the last month I discovered that it is now available in the US and EU — thus it is a good time to revisit it.
One of the characteristics that is connected with a lot of the stuff that my model suggests, is that they are often used for diarrhea and other digestive discomfort. In other words, been show effective against common disruptive bugs in the gut. Mutaflor (E.Coli Nissle 1917) and Miyarisan are both traditionally used for that — not as regular daily probiotics, but as probiotics when symptoms require the gut to be fixed. The interesting aspect is this:
- Mutaflor — the only E.Coli probiotic (and many E.Coli are nasty)
- Clostridium butyricum – the only Clostridium probiotic that I am aware of (and many Clostridium are Difficult (i.e. difficile))
Clostridium butyricum MIYAIRI 588® (CBM 588®), an anaerobic spore-forming bacterium, has been developed as a probiotic for use by humans and food animals.
- Safe – “the absence of genes for encoding for α, β, or ε toxins and botulin neurotoxins types A, B, E, or F.”
- “The bactericidal effect of butyric acid on H. pylori was stronger than that of lactic, acetic or hydrochloric acids…Cure of persistent infection with H. pylori in the gnotobiotic mice was demonstrated following infection with C. butyricum. 
“Clostridium butyricum might change the vitamin K production in the intestinal bacterial flora and attenuated the anticoagulation effect of warfarin.” 
[Multicenter, randomized, controlled clinical trial on preventing antibiotic-associated diarrhea in children with pneumonia using the live Clostridium butyricum and Bifidobacterium combined Powder .
Do NOT take with E.Coli Probiotics
“1.1 C. butyricum MIYAIRI antagonistic effects on toxinogenic Escherichia coli and 20 E. coli strains isolated from live stocks (cows, pigs and chickens) were evaluated by the plating method. C. butyricum MIYAIRI inhibited the growth of all E. coli strains tested” [Source]
- “Reduced anxiety levels from 19.8 to 10.2 in the HAMA Attenuated the increase in CRF and HR pre op”  
“An important mechanism by which butyrate causes biological effects in colon carcinoma cells is the hyperacetylation of histones by inhibiting histone deacetylase” 
“In humans, the effects of BA can be subdivided into intestinal and extra-intestinal. Intestinal effects include: regulating transepithelial transport, improving the inflammatory and oxidative states of the intestinal mucosa, reinforcing the mucosal barrier, modulating visceral sensitivity and motility, and preventing and inhibiting colon carcinoma. Extraintestinal effects are less well known; they have been studied in vitro and in animal models and sometimes even in humans. Currently investigated effects include: haemoglobinopathies, hypercholesterolaemia, reducing resistance to insulin (in animal studies), and reducing ischemic stroke (in animal studies).” 
Butyrate Studies with IBS
Butyrate is produced by Miyarisan.
“Butyrates represent a potential new IBS therapy. To date, a few trials have been performed to evaluate the effectiveness of sodium butyrate on clinical symptoms and quality of life in patients with IBS. Banasiewicz et al. performed a double-blind, randomized, placebo-controlled study in which 66 adult patients with IBS received microcapsulated butyric acid at a dose of 300 mg per day or placebo as an adjunct to standard therapy. At four weeks, there was a statistically significant decrease in the frequency of abdominal pain during defecation in the butyric acid group (p = 0.0032). At 12 weeks, decreases in the frequency of spontaneous abdominal pain (p = 0.0132), postprandial abdominal pain (p = 0.0031), abdominal pain during defecation (p = 0.0002) and urge after defecation (p = 0.0100) were observed [9, 10]. In a preliminary report, Tarnowski et al. demonstrated an improvement of abdominal pain, abdominal discomfort and defecation rhythm in patients with IBS treated with microcapsulated sodium butyrate for 6 weeks, compared to those treated with placebo. In the same study, higher quality of life was noted in patients treated with butyrate .” 
Both my wife and I found we slept hard when we started taking this. By hard, I mean sleeping thru four(4) alarm clocks. For myself, I woke with less adrenalin than usual, more relaxed. As usual, your experience may be different due to different microbiome.