Lactobacillus casei Shirota (LcS) for Constipation

Verdict: Published with Warning

Across 6 PubMed studies, the evidence for Lactobacillus casei Shirota (LcS) in Constipation grades Tier B — preliminary evidence. Effective, but with safety or population caveats.

B 🟡 B Preliminary Evidence Published with Warning

🔬Why this grade7-layer evidence engine

⚖️

Scoring transparency

All scores computed by a 7-layer evidence engine — fully auditable

Raw score 0.52

← counter-evidence / ineffectiveeffective / strong evidence →

Final grade

B · Published with Warning

Confidence

68%

Broadly consistent

Evidence level

Multiple high-quality MAs (≥2 independent, consistent)

How strongly each layer supports this effect

lower = less supportive

L2 PubMedPrimary literature

0.45

L3 MechanismPlausibility

0.45

L1 ExamineGlobal benchmark

0.50

L5 Clinical bodiesAuthoritative stance

0.62

L11 AI re-checkIndependent read

0.65

Against Mixed Supports

▸View the full decision path (audit trail)

compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.517
tier_from_score — 依分數區間映射至 tier letter
apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
tier_strict_requirement_check — Tier 條件達標，未降階
detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
decide_status — 依 tier + dispute 結果決定 status

📄PubMed studies (6)L2 · primary research & systematic reviews

The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials

PMID: 25099542 2014 統合分析 n = 1,182

Finding: Pooled probiotics improved transit time (-12.4 h), stool frequency (+1.3 BM/wk, 95% CI 0.7-1.9) and consistency (SMD +0.55), but the strain-specific analysis found Lactobacillus casei Shirota did NOT significantly improve stool frequency (WMD -0.2 BM/wk, 95% CI -0.8 to 0.9) or consistency (SMD +0.26, 95% CI -0.30 to 0.82); benefit was driven by Bifidobacterium lactis.

🟢 High quality Mixed funding Effect size: LcS-specific: stool frequency WMD -0.2 BM/wk (95% CI -0.8 to 0.9, NS); consistency SMD +0.26 (95% CI -0.30 to 0.82, NS)

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Probiotic beverage containing Lactobacillus casei Shirota improves gastrointestinal symptoms in patients with chronic constipation

PMID: 14631461 2003 RCT (double-blind) n = 70

Finding: LcS produced significant improvement in self-reported constipation severity and stool consistency from week 2 (P<0.0001), with a positive effect in 89% of LcS vs 56% of placebo subjects at study end (P=0.003).

Effect size: Responders 89% LcS vs 56% placebo (P=0.003)

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Effect of Daily Consumption of a Fermented Milk Containing Lacticaseibacillus paracasei Strain Shirota (LcS) on Stool Consistency in United States Adults with Hard or Lumpy Stools: A Randomized Controlled Trial

PMID: 40024315 2025 RCT (open-label) n = 50

Finding: LcS reduced the odds of having hard/lumpy stools in >=25% of BMs (OR 0.34, 95% CI 0.14-0.80, P=0.014) and improved constipation-specific quality of life (PAC-QOL, P=0.003), but the trial was open-label and a surrogate stool-consistency endpoint rather than a constipation diagnosis.

⚠️ Industry-funded Effect size: OR 0.34 for HLS in >=25% of BMs (95% CI 0.14-0.80, P=0.014)

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Fermented milk containing Lactobacillus casei strain Shirota reduces incidence of hard or lumpy stools in healthy population

PMID: 21322768 2011 RCT (open-label) n = 39

Finding: The proportion of subjects with frequent hard/lumpy stools fell from 73.7% to 36.8% on LcS while rising from 75.0% to 85.0% in controls (P=0.002), with significantly improved Bristol stool score (P<0.001), but in a healthy (non-clinically-constipated) population and non-blinded.

🟠 Limited quality ⚠️ Industry-funded Effect size: Hard/lumpy-stool subjects 73.7%->36.8% (LcS) vs 75.0%->85.0% (control), P=0.002

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Effects of Fermented Milk Containing Lacticaseibacillus paracasei Strain Shirota on Constipation in Patients with Depression: A Randomized, Double-Blind, Placebo-Controlled Trial

PMID: 34209804 2021 RCT (double-blind) n = 82

Finding: There was NO significant difference in total PAC-SYM constipation-symptom scores between LcS and placebo overall; only some sub-items (rectal/stool symptoms, items 7-12) and the inflammatory marker IL-6 (P<0.05) differed, so the primary constipation endpoint was null.

Effect size: Total PAC-SYM: no significant LcS vs placebo difference (null on primary endpoint)

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Systematic review of randomised controlled trials: probiotics for functional constipation

PMID: 20039451 2010 系統性回顧 n = 377

Finding: This earlier qualitative systematic review reported a favourable effect of B. lactis DN-173 010, L. casei Shirota and E. coli Nissle 1917 on defecation frequency and stool consistency, but rated the evidence preliminary and was later superseded by the strain-specific meta-analysis (PMID 25099542) that found LcS itself non-significant.

🟠 Limited quality Effect size: Qualitative 'favourable' for LcS; no pooled effect size reported

View on PubMed

🏛️Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …

L4a US FDA

Supportive

GRN No. 429 — Lactobacillus casei strain Shirota. Intended Use: As an ingredient in fermented dairy products at a maximum level of 4x10^8 colony forming units per milliliter. FDA Response: has no questions. Notifier: Yakult Honsha Co., Ltd. (Tokyo, Japan). Filed April 10, 2012; closed December 10, 2012. source↗

L4b EU EFSA

Against

The Panel concluded that a cause and effect relationship has not been established between the consumption of Lactobacillus casei Shirota and maintenance of the upper respiratory tract defence against pathogens by maintaining immune defences. The Panel considered that there was no human study demonstrating an effect of Lactobacillus casei Shirota consumption on upper respiratory tract infections… source↗

L4c UK NHS

Cautious

Probiotics are generally classed as food rather than medicine, which means they don't go through the rigorous testing medicines do. ... There's some evidence that probiotics may be helpful in some cases, such as helping to ease some symptoms of irritable bowel syndrome (IBS). ... If you have an existing health condition or a weakened immune system, you should talk to a doctor before taking any … source↗

L4d TW TFDA / 衛福部

Supportive

養樂多活菌發酵乳衛署健食字第A00032號胃腸功能改善；養樂多300LIGHT活菌發酵乳衛署健食字第A00128號免疫調節、輔助調整過敏體質、胃腸功能改善；養樂多300活菌發酵乳衛署健食字第A00178號胃腸功能改善 source↗

L4e WHO

Neutral

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The 2002 FAO/WHO Working Group Guidelines for the Evaluation of Probiotics in Food require strain-level identification (genus, species, strain), in vitro testing (acid/bile tolerance), safety assessment (antibiotic resistance, metabolic activities, no transferable resistance), and… source↗

L5a NIH Office of Dietary Supplements

Neutral

With a total listing of over 500 scientific studies...it is fair to say that the L. casei strain Shirota is the most researched probiotic strain in the world. Classified as Lacticaseibacillus paracasei Shirota since April 2020. source↗

L5d Harvard Health

Supportive

Probiotics increased 'gut transit time' by 12.4 hours, increased weekly bowel movements by 1.3, and softened stools. source↗

L5e Specialty Society (condition-mapped)

Neutral

The AGA-ACG Clinical Practice Guideline on the Pharmacological Management of Chronic Idiopathic Constipation (2023) makes strong recommendations for polyethylene glycol, sodium picosulfate, linaclotide, plecanatide, and prucalopride, and discusses fiber, osmotic/stimulant laxatives, secretagogues, and serotonin agonists; probiotics (including Lactobacillus casei Shirota / LcS / Yakult) are not … source↗

✓PMID 100% verifiedevery citation checked via NCBI Entrez

🔬6 PubMed studiesindependently re-checked by multiple sub-agents

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