I’ve lately been discussing how Lactobacillus casei Shirota, a bacterial species/strain available to us as the product Yakult, can be cultivated as “yogurt” to increase bacterial counts to enhance resistance to respiratory viruses. Several clinical studies in humans have demonstrated a 50% reduction in frequency of respiratory viral illness and, should you acquire one, 50% or greater shortening of the duration. While L casei Shirota has not yet been studied against COVID-19, there is no downside to cultivating this interesting species/strain. Beyond enhanced viral immunity, L. casei Shirota has also been shown to have substantial anti-inflammatory effects.
As with our L. reuteri adventures, however, there is more to L. casei Shirota than just enhanced immune and anti-inflammatory responses. There are also some fascinating effects on mood, anxiety, and stress.
Among the clinical studies that have examined the effects of L. casei Shirota:
- While students facing a stressful exam period experienced no reduction in perceived stress, they did experience a nearly 50% reduction in salivary cortisol levels, and marked reduction of cold symptoms and abdominal discomfort with consumption of 100 billion CFUs of L. casei Shirota per day over 8 weeks. There was also an increase in fecal serotonin, an interesting finding all by itself with implications for mood management.
- People with fibromyalgia/chronic fatigue syndrome experienced reduced anxiety over 8 weeks of consuming L. casei Shirota, 24 billion CFUs per day.
As with our efforts to enhance resistance to respiratory viruses that occurs more confidently with a daily intake of 100 billion CFUs, we use the Yakult product with only 6.5 billion CFUs per bottle as the starter for L. casei yogurt-making using the same methods that we use in making L. reuteri yogurt, though a shorter fermentation period of 24-36 hours is possible, as this species has a doubling time (time required for one bacteria to become two bacteria) of about 50% less than L. reuteri.
Now here is something to consider: If the strains of L. reuteri we use are known to increase oxytocin that increases empathy and human connection, what are the results of combining the effects of L. reuteri and L. casei, i.e., restoring both species/strains to bowel flora? Like L. casei, L. reuteri is also known to blunt the effects of stress-induced cortisol. I believe that we can expect a marked reduction in the effects of chronic stress, unhealthy consequences of prolonged stress, and an increase in social interaction and empathy.