Probiotics are microorganisms found in your intestinal tract called "friendly bacteria" because they are helpful for overall health. Up to 70 percent of your immune system’s activity lies within intestinal tissues, which is why it’s so important to nourish your intestinal tract with a good diet and supplements. The Lactobacillus Shirota probiotic has demonstrated both positive and mixed results in promoting intestinal health and treating other conditions.
Hundreds of studies have investigated various types of the Lactobacillus group of probiotics for immunity, arthritis, Crohn’s disease, skin conditions, high cholesterol, cancer, and diarrhea and constipation. Due to encouraging results from these studies, manufacturers have created several different probiotic formulas. The Yakult Shirota strain of Lactobacillus bacteria was originally isolated from a human intestine in 1930 and named after its discoverer, Minoru Shirota. The only company using Shirota is the Yakult Honsha Company in Japan, which sells a milk-like beverage containing Shirota casei probiotics.
Although research has linked Shirota probiotics to gastrointestinal benefits, almost every single one of these studies has been sponsored by the Yakult Central Institute for Microbiological Research. One independent study in Italy investigated the Yakult fermented milk drink on Parkinson’s patients with chronic constipation. The results, published in “Minerva Gastroenterologica e Eietologica” in June 2011, found six weeks of consuming a Lactobacillus casei Shirota drink daily led to significantly improved stool consistency and bowel habits in the Parkinson's patients.
A study at Japan’s Juntendo University, published in the April 2011 “British Journal of Nutrition,” found that, although consuming the Shirota-containing drink didn’t prevent a viral gastroenteritis at a nursing home, it did help reduce fever associated with the disease.
Immune System Benefits
Natural killer cells, also known as NK cells, are a type of white blood cell important to your immune system. A study published in the March 2007 issues of the “The Journal of Nutrition” showed that drinking the Shirota beverage daily for three weeks increased elevated NK cell activity in study subjects. However, a contradictory study in the same publication in May 2011 reported that the Shirota drink had no significant effect on NK cell numbers and function in healthy male patients.
The only studies testing Lactobacillus casei Shirota on insulin resistance have been by the Yakult research center. However, their results, published in March 2011 in the “Journal of Applied Microbiology,” showed that the probiotic improved insulin resistance and glucose intolerance in obese mice. Hopefully, independent studies and human clinical trials will be able to duplicate these benefits.
- “Applied and Environmental Microbiology”; The Scientific Basis for Probiotic Strains of Lactobacillus; Gregor Reid; September 1999
- “Minerva Gastroenterologica e Eietologica”; Use of Probiotics for the Treatment of Constipation in Parkinson's Disease Patients; E. Cassasni, et al.; June 2011
- “British Journal of Nutrition”; Effect of the Continuous Intake of Probiotic-Fermented Milk Containing Lactobacillus Casei Strain Shirota on Fever...; S. Nagata, et al.; April 2011
- “Journal of Applied Microbiology”; Beneficial Effect of Oral Administration of Lactobacillus Casei Strain Shirota on Insulin Resistance in Diet-Induced Obesity Mice; E. Naito; March 2011
- “The Journal of Nutrition”; Effects of a Fermented Milk Drink Containing Lactobacillus casei Strain Shirota on the Human NK-Cell Activity; Kazuyoshi Takeda and Ko Okumura; March 2007
- “The Journal of Nutrition”; Probiotic Lactobacillus casei Shirota Supplementation Does Not Modulate Immunity in Healthy Men with Reduced Natural Killer Cell Activity; S. Seifert, et al.; May 2011