Entry 30

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Lacticaseibacillus rhamnosus HN001

Lacticaseibacillus rhamnosus HN001

Uses immune modulation to reduce eczema prevalence through age 11 and improve postpartum mental health, with long-term RCT support.

Dermatological

Psychobiotic

immunological

Evidence strength

5 / 5

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Overview

Lacticaseibacillus rhamnosus HN001 (formerly Lactobacillus rhamnosus HN001) is a probiotic strain. It was originally isolated from human dairy cultures in New Zealand (DR20 designation). Danisco/DuPont (now IFF) commercialized it as Howaru Rhamnosus [1,6]. Following the 2020 reclassification of the genus Lactobacillus by Zheng et al., the species moved to the new genus Lacticaseibacillus [7]. HN001 is one of the most clinically studied L. rhamnosus strains for pediatric allergy prevention. Landmark RCTs demonstrate long-term eczema prevention and postpartum mood benefits [1,2,3]. It is distinct from L. rhamnosus GG (ATCC 53103). That is the most widely studied strain of the same species. The two differ in genomic content, surface antigen profile, and clinical evidence base [6].

Mechanism

L. rhamnosus HN001 sticks to cells lining the gut. It does this via surface-layer proteins and mucus-binding proteins. This enables transient but persistent colonization of the gut mucosa [6]. The strain enhances intestinal barrier function. It upregulates tight junction protein expression (occludin, claudin-1). It protects the blood-brain barrier from inflammatory disruption. Lab tests demonstrated this [4] (in vitro). HN001 tunes the immune system. It promotes Treg differentiation and Th1/Th2 balance. This shifts away from the allergy-associated Th2 skew [1]. Lab tests confirmed that HN001 alters the infant gut microbiome functional capacity (metabolic pathway enrichment). It does so without significantly changing taxonomic composition. This suggests that probiotic effects work through metabolic reprogramming rather than compositional shifts [5] (RCT substudy). Intra-species genomic variability among L. rhamnosus strains, including HN001, significantly impacts carbohydrate utilization signatures and stress resistance. This explains strain-specific probiotic effects [6] (genomics).

Health Benefits

A two-center, double-blind RCT enrolled 474 mother-infant pairs. It demonstrated that HN001 supplementation (6 × 10^9 CFU (colony-forming units, a live bacteria count) per day) from 35 weeks’ gestation through 6 months postpartum in mothers, and from birth to age 2 years in infants, significantly reduced eczema prevalence at ages 2, 4, 6, and 11 years. At 11 years, RR = 0.46 (95% CI 0.25-0.86, P = 0.015 for 12-month eczema prevalence). HR = 0.58 (95% CI 0.41-0.82, P = 0.002 for lifetime eczema). The study also showed reduced atopic sensitization and hay fever. This was the first probiotic intervention showing sustained allergy prevention through the first decade of life [1] (RCT). However, a separate RCT found that maternal supplementation alone with HN001 during pregnancy and breastfeeding (without infant supplementation) did not reduce infant eczema. This suggests direct infant exposure is important [2] (RCT). A double-blind RCT found that HN001 supplementation during pregnancy significantly reduced postpartum depression and anxiety scores (Edinburgh Postnatal Depression Scale) [3] (RCT). In lab tests, HN001 enhanced intestinal barrier function and protected blood-brain barrier integrity under inflammatory conditions [4] (in vitro). A systematic review of animal studies confirmed therapeutic effects of L. rhamnosus on stress-induced anxiety [8]. Evidence quality for eczema prevention is high. For mental health outcomes, evidence is emerging.

Biology

Lacticaseibacillus rhamnosus HN001 is a Gram-positive, non-spore-forming, non-motile rod. It measures approximately 0.5 × 1-3 µm. It belongs to the Lactobacillaceae family within the phylum Bacillota [6,7]. Following the 2020 taxonomic reclassification of the genus Lactobacillus, L. rhamnosus moved to the new genus Lacticaseibacillus as Lacticaseibacillus rhamnosus [7]. The earlier genus name Lactobacillus remains in primary use in clinical literature. Its metabolism produces lactic acid plus other byproducts from sugar. It produces predominantly L-lactic acid from hexoses. The species does not produce gas from glucose [6]. HN001 is catalase-negative. It grows optimally at 37°C. It tolerates bile salts and low pH [6]. Intra-species genomic analysis reveals that L. rhamnosus strains differ significantly in carbohydrate utilization gene clusters, bacteriophage (a virus that infects bacteria) content, and exopolysaccharide biosynthesis loci. HN001 displays a distinct carbohydrate utilization phenotype [6]. Natural isolation sources include dairy products and the human intestinal tract [6].

Bibliography

  1. Wickens K, Barthow C, Mitchell EA, et al. (2018). Effects of Lactobacillus rhamnosus HN001 in early life on the cumulative prevalence of allergic disease to 11 years. Pediatric Allergy and Immunology. 29(8):808-814. PMID: 30430649

  2. Wickens K, Barthow C, Mitchell EA, et al. (2018). Maternal supplementation alone with Lactobacillus rhamnosus HN001 during pregnancy and breastfeeding does not reduce infant eczema. Pediatric Allergy and Immunology. 29(3):296-302. PMID: 29415330

  3. Slykerman RF, Hood F, Wickens K, et al. (2017). Effect of Lactobacillus rhamnosus HN001 in pregnancy on postpartum symptoms of depression and anxiety: a randomised double-blind placebo-controlled trial. EBioMedicine. 24:159-165. PMID: 28943228

  4. Ulluwishewa D, Purba A, Fegan V, et al. (2026). Lacticaseibacillus rhamnosus HN001 enhances intestinal barrier function and protects the blood-brain barrier from inflammatory disruption in vitro. Frontiers in Physiology. 17:1808663. PMID: 42180834

  5. Murphy R, Morgan XC, Wang XY, et al. (2019). Eczema-protective probiotic alters infant gut microbiome functional capacity but not composition: sub-sample analysis from a RCT. Beneficial Microbes. 10(1):5-17. PMID: 30574802

  6. Ceapa C, Lambert J, van Limpt K, et al. (2015). Correlation of Lactobacillus rhamnosus genotypes and carbohydrate utilization signatures determined by phenotype profiling. Applied and Environmental Microbiology. 81(16):5458-5470. PMID: 26048937

  7. Zheng J, Wittouck S, Salvetti E, et al. (2020). A taxonomic note on the genus Lactobacillus: description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. International Journal of Systematic and Evolutionary Microbiology. 70(4):2782-2858. PMID: 32293557

  8. Juvale IIA, Arulsamy A. (2025). “The therapeutic effects of Lacticaseibacillus rhamnosus on stress-induced anxiety: a systematic review of evidence from animal studies.” Gut Microbiome. 6:eXX. PMID: 41497537

Available Products

Danisco/DuPont (now IFF, New York, USA) supplies Howaru Rhamnosus HN001 as a probiotic ingredient for dietary supplements, dairy products, and infant formula [1,6]. The strain is marketed in capsules, powders, and dairy matrices. Clinical doses range from 6 × 10^9 to 1 × 10^10 CFU per day [1,3]. HN001 is also incorporated into pediatric formulations and maternal supplements. These are distributed globally [1].

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