Lactobacillus casei and Lactobacillus paracasei, now named Lacticaseibacillus, are probiotic bacteria. The best-studied strain, Shirota (LcS), has been tested in fermented milk; it is now classed as L. paracasei.
Also known as: Lacticaseibacillus paracasei, Lacticaseibacillus casei, L. casei Shirota, LcS, L. paracasei.
Student trials used 100 mL a day of LcS-fermented milk for 8 weeks before an exam (Takada 2017). A Parkinson's trial used fermented milk with 10 billion live LcS a day for 12 weeks (Yang 2023). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: in pooled trials of medical students facing a national exam, 8 weeks of LcS-fermented milk kept the stress hormone cortisol and physical symptoms lower than placebo milk (Takada 2016), and preserved deep sleep as the exam approached (Takada 2017). In 128 people with Parkinson's disease, 12 weeks of LcS eased constipation and other non-movement symptoms (Yang 2023). For chronic constipation in adults generally, a 2022 meta-analysis found L. casei Shirota did not significantly increase stool frequency (van der Schoot 2022).
Safety: the sources here do not report safety problems. The sources here do not describe drug interactions.
Probiotics are live bacteria that act in the gut rather than being absorbed into the blood, so a half-life or time to peak does not apply.
How Dose Track handles peptides · Reconstitution calculator · Half-life calculator