Home Ingredients Lactobacillus fermentum CECT5716 (Lc40 / Hereditum®)
Women's HealthImmune Support

Lactobacillus fermentum CECT5716 (Lc40 / Hereditum®)

Limosilactobacillus fermentum CECT5716 (formerly Lactobacillus fermentum CECT5716)
Evidence Level
Strong
3 Clinical Trials
6 Documented Benefits
4/5 Evidence Score

Lactobacillus fermentum CECT5716 (commercialized as Lc40 and Hereditum®) is a probiotic strain originally isolated from human breast milk. Its primary indication is the prevention and management of infectious mastitis in breastfeeding women — one of the best-evidenced single-strain probiotics for this specific application. Multiple randomized trials show meaningful reductions in mastitis recurrence and breast pain when taken daily during lactation. Also has evidence for infant immune support and reduced gastrointestinal infections in formula-fed infants. The honest framing: a highly specific use case — breastfeeding mastitis prevention and management — where the evidence is strong and clinically meaningful. Less established for general adult or pediatric use beyond this specific indication.

Studied Dose Mastitis: 3×10⁹ CFU/day for ≥21 days. Hereditum® formulations: 1-3 billion CFU/day.
Active Compound Limosilactobacillus (Lactobacillus) fermentum CECT5716; trademarked HEREDITUM®/Lc40 (Biosearch Life).

Benefits

Mastitis prevention in breastfeeding women

Multiple randomized trials show L. fermentum CECT5716 reduces recurrence of infectious mastitis in women with prior history. One of the best-evidenced probiotic applications — taken daily during lactation for sustained protection.

Supported by Trial 1, Trial 2

Mastitis treatment effectiveness

Trials show L. fermentum CECT5716 is comparable to oral antibiotics for treating acute mastitis episodes, with similar pain reduction and bacterial load reduction in breast milk. An antibiotic-sparing option for selected cases.

Supported by Trial 1

Reduced breast pain during lactation

Beyond infectious mastitis specifically, L. fermentum CECT5716 reduces breast pain and discomfort during breastfeeding in women with sensitive ducts or recurrent issues. Supports continued breastfeeding.

Supported by Trial 1, Trial 2

Infant respiratory and GI infection reduction

Trials in formula-fed infants show L. fermentum CECT5716 supplementation reduces respiratory and gastrointestinal infections compared to standard formula. Reflects strain effects beyond just maternal applications.

Supported by Trial 1, Trial 3

Originally isolated from human milk

The strain was originally isolated from healthy breast milk, providing a biological rationale for its safety in maternal and infant populations. Approved for use during lactation in regulatory frameworks where many supplements aren't.

Supported by Trial 1

Antimicrobial peptide production

L. fermentum CECT5716 produces antimicrobial compounds active against the common mastitis pathogens (Staphylococcus species). Mechanism explains both the prevention and treatment benefits seen in clinical trials.

Supported by Trial 1, Trial 2

Mechanism of action

1

Mammary microbiota niche specialization (breast milk origin)

Originally isolated from healthy breast milk — the strain is naturally adapted to the mammary environment. Niche specialization is the proposed basis for selective benefit at this site vs other Lactobacillus strains isolated from gut or vaginal sources.

2

Staphylococcus competitive exclusion

Trial data reported significantly lower Staphylococcus spp. load in breast milk of the probiotic group. Staphylococcus is the main causal agent of mastitis. Competitive exclusion via niche occupation, antimicrobial peptide production, and lactic acid / low-pH maintenance are the proposed mechanisms.

3

Antimicrobial peptide production

Bacteriocin-like substances active against Staphylococcus species are produced by L. fermentum CECT5716 in vitro. This is a foundational mechanism for the Staphylococcus-load reduction observed clinically.

4

Lactic acid and low-pH maintenance

Lactobacillus species produce lactic acid lowering local pH — a foundational antimicrobial mechanism that disadvantages alkaline-tolerant pathogens including some Staphylococcus species.

5

Mammary microbiota dysbiosis correction

Painful breastfeeding and mastitis are associated with dysbiosis of the mammary microbiota — Staphylococcus overgrowth at the expense of normal commensals. Restoring commensal balance is the proposed broader mechanism beyond direct Staphylococcus suppression.

Clinical trials

1
Mastitis Prevention 625-Women Clinical Trial

Clinical evidence on Lactobacillus fermentum CECT5716 (Lc40 / Hereditum®) for the indications and outcomes described.

625 women

Hurtado JA et al. 2017, Breastfeeding Medicine, NCT02203877, PROLAC Group multicenter investigation. Randomized double-blind placebo-controlled multicenter trial in 625 women (291 completed 16-week treatment) recruited 1-6 days post-childbirth. Probiotic: 3×10⁹ CFU/day L. fermentum CECT5716 vs maltodextrin placebo for 16 weeks. Clinical mastitis incidence rate 0.130 (probiotic) vs 0.263 (control), p=0.021 — 51% reduction. Staphylococcus spp. load significantly reduced in breast milk (p=0.025). The pivotal evidence base for the indication.

2
Hereditum® Mastitis Treatment Dose-Ranging Clinical Trial

4-arm dose-ranging trial (3×10⁹, 6×10⁹, 9×10⁹ CFU/day, plus placebo) for 3 weeks in women with painful breastfeeding.

Clinical population described in trial publication.

4-arm dose-ranging trial (3×10⁹, 6×10⁹, 9×10⁹ CFU/day, plus placebo) for 3 weeks in women with painful breastfeeding. Significant Staphylococcus reduction across active arms. Supports the 3×10⁹ CFU/day dose carried forward into prevention.

3
Australian Clinical Trial Protocol

Clinical evidence on Lactobacillus fermentum CECT5716 (Lc40 / Hereditum®) for the indications and outcomes described.

Clinical population described in trial publication.

Bond DM et al. 2017, BMC Pregnancy and Childbirth, doi:10.1186/s12884-017-1330-8. Australian clinical trial protocol from Kolling Institute Sydney, Menzies Centre, and Sydney Medical School Northern. Geographic generalizability framework with explicit WHO antibiotic-resistance framing — probiotic alternative to antibiotic prophylaxis.

Side effects and drug interactions

Common Potential side effects

Generally extremely well-tolerated; isolated from breast milk = naturally human-adapted strain.
Mild GI upset (rare; transient).
Pregnancy/lactation: especially designed for lactating women — extensive 16-week safety record.
Long-term safety: 16-week multicenter RCT in 625 women supportive.
Allergic reactions (rare).
Severely immunocompromised individuals: caution (applies to all probiotics).
Industry-sponsorship (Biosearch Life Hereditum®) — important context.

Important Drug interactions

Antibiotics: take 2-3 hours apart from L. fermentum CECT5716 dose.
Mastitis-treatment antibiotics (cloxacillin, dicloxacillin): may be reduced or avoided with prophylactic Hereditum® per emerging evidence.
Most medications: well-tolerated combination profile.
Immunosuppressants: caution.
Other probiotics: compatible.
Anticoagulants: no interactions documented.
Hormonal contraceptives: no interactions documented (relevant to postpartum population).

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Frequently asked questions about Lactobacillus fermentum CECT5716 (Lc40 / Hereditum®)

What is Lactobacillus fermentum CECT5716?

Lactobacillus fermentum CECT5716 (commercialized as Lc40 and Hereditum®) is a probiotic strain originally isolated from human breast milk. Its primary indication is the prevention and management of infectious mastitis in breastfeeding women — one of the best-evidenced single-strain probiotics for this specific applicat…

What is Lactobacillus fermentum CECT5716 used for?

Lactobacillus fermentum CECT5716 is researched primarily for Women's Health and Immune Support. Multiple randomized trials show L. fermentum CECT5716 reduces recurrence of infectious mastitis in women with prior history. One of the best-evidenced probiotic applications — taken daily during lactation for sustained protection.

What is the recommended dosage of Lactobacillus fermentum CECT5716?

The clinically studied dose is Mastitis: 3×10⁹ CFU/day for ≥21 days. Hereditum® formulations: 1-3 billion CFU/day. Always follow the product label and check with a healthcare provider for personal advice.

Is Lactobacillus fermentum CECT5716 safe, and does it have side effects?

For most healthy adults, Lactobacillus fermentum CECT5716 is well tolerated at studied doses. Reported effects can include: Generally extremely well-tolerated; isolated from breast milk = naturally human-adapted strain. Mild GI upset (rare; transient). It may also interact with some medications. Lactobacillus fermentum CECT5716 is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Lactobacillus fermentum CECT5716 interact with any medications?

Possible interactions include: Antibiotics: take 2-3 hours apart from L. fermentum CECT5716 dose. Mastitis-treatment antibiotics (cloxacillin, dicloxacillin): may be reduced or avoided with prophylactic Hereditum® per emerging evidence. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Lactobacillus fermentum CECT5716?

NutraSmarts rates the evidence for Lactobacillus fermentum CECT5716 as Strong (4 out of 5). It is backed by 3 clinical trials and 3 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(3 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Arroyo R, Martin V, Maldonado A, Jimenez E, Fernandez L, Rodriguez JM Treatment of infectious mastitis during lactation: antibiotics versus oral administration of Lactobacilli isolated from breast milk Clinical Infectious Diseases. 2010;50(12):1551-8. doi: 10.1086/652763.PubMedUsed to support: Backs the core mastitis-treatment claim for this strain: oral L. fermentum CECT5716 resolved infectious lactational mastitis at least as well as antibiotics, with lower recurrence, in breastfeeding women. Honest limits: strain-specific but industry-linked; an open-label design with subjective pain endpoints.
  2. Maldonado-Lobon JA, Diaz-Lopez MA, Carputo R, Duarte P, Diaz-Ropero MP, Valero AD, Sanudo A, Sempere L, Ruiz-Lopez MD, Banuelos O, et al. Lactobacillus fermentum CECT 5716 Reduces Staphylococcus Load in the Breastmilk of Lactating Mothers Suffering Breast Pain: A Randomized Controlled Trial Breastfeeding Medicine. 2015;10(9):425-32. doi: 10.1089/bfm.2015.0070.PubMedUsed to support: Backs the mastitis-prevention/breast-pain mechanism: 3 weeks of L. fermentum CECT5716 lowered breastmilk Staphylococcus load and reduced breast pain vs placebo in lactating women. Honest limits: small strain-specific RCT funded by the strain manufacturer; a surrogate (bacterial load) endpoint rather than clinical mastitis incidence.
  3. Gil-Campos M, Lopez MA, Rodriguez-Benitez MV, Romero J, Roncero I, Linares MD, Maldonado J, Lopez-Huertas E, Berwind R, Ritzenthaler KL, et al. Lactobacillus fermentum CECT 5716 is safe and well tolerated in infants of 1-6 months of age: a randomized controlled trial Pharmacological Research. 2012;65(2):231-8. doi: 10.1016/j.phrs.2011.11.016.PubMedUsed to support: Backs the infant gut/immune and safety claim: an infant formula with L. fermentum CECT5716 was safe and well tolerated in infants 1-6 months and was associated with fewer gastrointestinal infections. Honest limits: strain-specific but industry-sponsored; powered for safety/tolerance rather than as a definitive efficacy trial.