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Lactobacillus casei

Probioticlactic acid bacteriaModerate dose evidence

Also known as: L. casei, Lacticaseibacillus casei, L. paracasei Shirota, Shirota strain, DN-114 001, Lc-11

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Lactobacillus casei is a lactic acid bacterium closely related to L. paracasei and L. rhamnosus, best known from fermented milk drinks built on the Shirota strain, which has been studied in randomized trials for irritable bowel symptoms and for constipation-related outcomes. It is used in digestive and immune blends and as a companion to Bifidobacterium strains. Supplement suppliers offer freeze-dried L. casei at 1–10 billion CFU per serving; nomenclature is in flux, so strain codes and the updated genus name may both appear on certificates of analysis.

Research summary

Produces lactic acid; studied for effects on gut transit and on mucosal immune signaling.

Gut & digestionImmune

Dosage

Daily amounts, of compound. CFU shown in billions.

Lowest studiedTypical rangeHighest studiedUpper limit
1 B CFU1–10 B CFU——

Amounts are in billions of CFU (enter 5 for 5 billion). Raw-material weight assumes a 100 billion CFU/g concentrate (10 mg per billion CFU); manufacturers add a 20–50% CFU overage at fill so the label claim holds through shelf life, and the label should state whether CFU are guaranteed at manufacture or at expiry. Most Shirota data come from fermented milk rather than freeze-dried capsules.

Standardization: Strain-designated freeze-dried culture; CFU per gram on CoA

Source material: freeze-dried culture

As supplied: Assumes 100 billion CFU/g concentrate (10 mg per billion CFU); adjust to supplier CoA.

Forms of Lactobacillus

FormTypical doseElement %FormatsPrice
Lactobacillus casei1–10 B CFU—Capsule, Powdermid
Lactobacillus acidophilus1–10 B CFU—Capsule, Powdermid
Lactobacillus reuteri (DSM 17938)0.1–1 B CFU—Capsule, Powderhigh
Lactobacillus plantarum1–10 B CFU—Capsule, Powdermid
Lactobacillus gasseri1–10 B CFU—Capsule, Powdermid

Format suitability

  • Capsule
  • Powder
  • Tablet
  • Softgel
  • Gummy
  • Liquid

Heat- and moisture-sensitive vegetative cells; capsule or dry powder only.

Formulation notes

Separate from antibiotic dosing by at least two hours. Often grown on dairy-based media; confirm allergen status with the supplier.

Sources

  1. NIH ODS — Probiotics Fact Sheet for Health ProfessionalsNIH ODS
  2. Efficacy of Lactobacillus casei Shirota for patients with irritable bowel syndrome. (Thijssen 2016)PubMed
  3. Effects of Fermented Milk Containing Lacticaseibacillus paracasei Strain Shirota on Constipation in Patients with Depression: A Randomized, Double-Blind, Placebo-Controlled Trial. (Zhang 2021)PubMed

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