Benefits
Immune support in infants fed a follow-on formula
In 192 healthy infants aged 6 to 12 months, 12 weeks of follow-on formula with HN019 was followed by fewer physician-confirmed upper respiratory infections than formula without probiotics (0% versus 9.4%), the main outcome. Only 8 cases occurred in all, the p value would not pass a correction for comparing two probiotic formulas with one control, Fonterra ran the trial, and it has not been repeated.
Gut transit time and bowel movements in adults
In a 14-day trial in 100 adults with functional digestive symptoms, HN019 at 17.2 or 1.8 billion CFU a day shortened whole-gut transit time compared with placebo. Three later, larger maker-funded trials in adults with constipation, lasting 4 to 8 weeks, found no difference from placebo on their main outcomes, so a bowel benefit is not established.
Blood immune cell activity in older adults (markers only)
In older adults, 3 weeks of milk with HN019 raised the share of some T cells and NK cells and the lab activity of phagocytes and NK cells against a milk run-in, and in a 25-person placebo-controlled trial 6 weeks raised interferon-alpha release versus plain milk, while phagocyte capacity rose within the HN019 group. These are lab markers; infections were not counted.
Gum bleeding scores alongside professional teeth cleaning
In 60 adults with plaque-related gum inflammation who had a professional cleaning, lozenges with HN019 (1 billion CFU twice a day) for 8 weeks were followed by less bleeding on probing, the main outcome, and lower inflammatory markers in gum fluid than placebo lozenges. Plaque did not differ. One small trial; the maker donated the probiotic.
Infant skin outcomes in a New Zealand birth cohort
In a New Zealand trial of 474 infants at high allergy risk, HN019 at 9 billion CFU a day (mothers from 35 weeks of pregnancy, infants from birth to age 2) did not lower cumulative eczema by age 2 versus placebo (hazard ratio 0.90) and had no significant effect at follow-ups to age 11. The sister strain HN001, given the same way, did.
Results from milk with HN019 plus a prebiotic
In a year-long trial in 624 children aged 1 to 3 in India, milk with HN019 (about 19 million CFU a day) plus 2.4 g of prebiotic oligosaccharides did not lower diarrhea overall versus control milk, while days with severe illness were 16% fewer. Fonterra funded it. This result belongs to the combination, not to HN019 alone.
Mechanism of action
Innate immune cell activity (human markers)
Across three small studies in middle-aged and older adults, milk with HN019 raised phagocyte engulfing activity and NK cell tumor killing in lab tests, with larger gains in people with weak baseline responses and when the strain was taken in lactose-hydrolyzed milk. Milk alone had little effect on most of these measures.
Passage through the gut
In the New Zealand infant trial, HN019 was found in the stool of 22.6% of infants at 3 months, compared with 71.5% for L. rhamnosus HN001, though detection was similar by 24 months. In Indian preschool children given 5 billion CFU a day, stool HN019 counts tracked total bacterial counts.
Strain-specific effects
HN019 and its sister strain HN001 were tested head to head twice: HN001, not HN019, lowered infant eczema in New Zealand, while HN019, not HN001, reached nominal significance on confirmed infections in a Chinese formula trial. The two strains are not interchangeable, and neither result carries over to other B. lactis strains.
Clinical trials
Randomized, triple-blind, placebo-controlled trial; HN019 at 17.2 or 1.8 billion CFU a day or rice maltodextrin placebo in capsules for 14 days; primary outcome whole-gut transit time by X-ray of radiopaque markers. Funded by Fonterra; capsules supplied by Danisco, and some authors worked for Fonterra or Danisco (Waller et al. 2011, Scand J Gastroenterol)
100 adults with functional gastrointestinal symptoms (mean age 44, 64% women).
Transit time fell from 49 to 21 hours on the high dose and from 60 to 41 hours on the low dose, with no change on placebo (43 to 44 hours); adjusted for baseline, day 14 transit time differed among the three groups (p=0.001). Eight of nine symptoms fell in frequency on the high dose versus two on placebo. No adverse events were reported.
Double-blind, randomized, placebo-controlled, dose-ranging trial; HN019 at 1 or 10 billion CFU a day or placebo for 28 days in adults with functional constipation (Rome III). Primary outcome: colonic transit time; secondary outcomes included symptom and quality of life scores, bowel movement frequency, stool consistency, straining, bloating and pain. Sponsored by DuPont Nutrition and Health, which employed two authors (Ibarra et al. 2018, Gut Microbes)
228 adults meeting Rome III criteria, randomized to one of two HN019 doses or placebo.
No statistically significant difference between groups in the primary outcome or any secondary outcome. In a post hoc subgroup of 65 people with 3 or fewer movements a week, the pooled HN019 groups had more weekly movements than placebo (p=0.01), and the high dose reduced straining (p=0.02); post hoc results need confirmation. Three adverse events judged unlikely to be related occurred.
Randomized, triple-blind, placebo-controlled trial at 5 Shanghai hospitals (ChiCTR2000029215) in adults with functional constipation (Rome III); HN019 at about 7.0 billion CFU a day at the start and 4.69 billion at the end, or maltodextrin placebo, for 8 weeks after a 2-week run-in. Primary outcome: change in weekly complete spontaneous bowel movements. Funded in full by Danisco China, part of IFF, which employed several authors (Cheng et al. 2024, JAMA Netw Open)
229 adults aged 18 to 70 (85% women) with 3 or fewer complete spontaneous movements a week after run-in.
Weekly complete spontaneous movements rose by 0.80 on HN019 and 0.66 on placebo, and the change did not differ between groups. The authors concluded that HN019 at 4.69 billion CFU a day did not outperform placebo.
Triple-blind, randomized, placebo-controlled trial at four clinical units in France (NCT04231162) in adults with functional constipation (Rome III); daily HN019 or placebo for 8 weeks after a 2-week screening. Primary outcome: complete spontaneous bowel movements; stool consistency, straining, pain, bloating and rescue medication use were also assessed. Several authors worked for IFF, the strain's supplier (Ala-Jaakkola et al. 2025, Mol Nutr Food Res)
Adults with 3 or fewer complete spontaneous movements a week in daily diaries during screening.
HN019 was not found superior to placebo, and the expected rise in complete spontaneous movements was not seen. Fecal moisture, microbial and calprotectin measures in half of the participants did not differ between groups. No safety concerns were identified.
Randomized, double-blind, placebo-controlled trial in Fuyang, China, in winter (NCT01724203); follow-on formula with HN019, with L. rhamnosus HN001 (each at 1 million CFU per gram), or without added probiotics for 12 weeks. Primary outcome: physician-confirmed infections. Stool frequency and consistency did not differ. The registry lists Fonterra Research Center as sponsor, a Shanghai hospital as site and completion in April 2013; two of three authors worked for Fonterra (Dekker et al. 2022, Benef Microbes)
192 healthy infants aged 6 to 12 months (64 per group).
All 8 confirmed infections were upper respiratory infections: 9.4% of controls, 3.1% on HN001 (p=0.273) and 0% on HN019 (p=0.028). Parent-reported upper respiratory infections were 25.0%, 14.1% and 9.4% (HN019 versus control p=0.019). No HN019 infant was prescribed antibiotics or antivirals, versus 7 controls. The confirmed result rests on 8 cases, and with two probiotic arms each compared with control, p=0.028 would not pass a Bonferroni cutoff of 0.025.
Three-stage trial over 9 weeks without a separate placebo group: 3 weeks of low-fat milk (run-in), 3 weeks of milk with HN019 at about 50 billion or 5 billion organisms a day, then a 3-week milk washout; changes were tracked over time against the run-in. Outcomes were blood immune markers measured in the lab (Gill et al. 2001, Am J Clin Nutr)
30 healthy elderly volunteers aged 63 to 84 (median 69).
After HN019, the proportions of total, helper (CD4+) and activated (CD25+) T cells and NK cells rose, as did phagocytic capacity and NK tumor-cell killing in the lab, with the largest gains in people with poor baseline responses. The two doses had similar effects. Infections were not measured.
Two-center, double-blind, randomized, placebo-controlled trial (ACTRN12607000518460); HN001 6 billion CFU/day or B. lactis HN019 9 billion CFU/day, taken by mothers from 35 weeks of pregnancy to 6 months postpartum if breastfeeding and by infants from birth to age 2; follow-ups at 4, 6 and 11 years. Funders listed for the 11-year report include Fonterra, the Health Research Council of New Zealand and Cure Kids (Wickens et al. 2008, J Allergy Clin Immunol)
474 infants at high risk of allergic disease; 425 seen at age 4.
HN001 lowered cumulative eczema by age 2 (hazard ratio 0.51, P=0.01); HN019 did not (0.90). Skin-prick sensitization at age 2 did not differ. The HN001 effect on eczema held at age 4 (0.57), 6 (0.56) and 11 (0.58), with lower sensitization at 6 and 11 years. HN019 had no significant effect on any outcome.
Double-blind, randomized, placebo-controlled trial at the University of Sao Paulo dental school in Brazil (RBR-59v2yb); after professional supragingival scaling and prophylaxis, lozenges with HN019 (HOWARU® Bifido, 1 billion CFU each) or placebo lozenges twice a day for 8 weeks. Primary outcome: mean bleeding on probing at 8 weeks. Danisco Sweeteners Oy donated the probiotics; the authors declared no competing interests (de Almeida Silva Levi et al. 2023, Clin Oral Investig)
60 adults with plaque-induced generalized gingivitis (30 per group); 53 analyzed after 7 were lost when dental care was interrupted during COVID-19.
At 8 weeks the HN019 group had a lower percentage of sites bleeding on probing and more sites with a low gingival index than the placebo group (p<0.0001), more patients no longer met the gingivitis definition (20 versus 11), and gum fluid IL-1 alpha, IL-1 beta and MCP-1 were lower. Plaque fell in both groups without a difference. No adverse events were reported.