Regular readers of my “Supplement Science” column may notice that this is the third postbiotic article I’ve written for Vitamin Retailer over the past few years—the other two being “Akkermansia muciniphila: A GLP-1 Promoting Postbiotic for Weight Loss” and “A Lactobacillus plantarum postbiotic for Immunity.” Considering that the market for postbiotics, the newest of the biotics category is growing, this makes sense. In fact, the postbiotic market was valued at $1.6 billion in 2021, and is estimated to reach $3 billion by 2031, growing at a CAGR of 6.8 percent.1 This third postbiotic article is about the Lactobacillus acidophilus strain L-92 (distributed globally by Maypro) which, as the title suggests, has applications for allergy, skin health and immune health. Let’s start with a brief definition.
Defining Postbiotics
According to International Scientific Association for Probiotics and Prebiotics (ISAPP), postbiotics are defined as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host.”2 Essentially, a postbiotic could be virtually any probiotic that has been pasteurized or otherwise heat-treated, and yet still provides health benefits—a sort of zombie probiotic if you will. Despite this treatment, research3 has demonstrated that postbiotics continue to offer health-related benefits. Another advantage of a postbiotic is that, since it is already dead, you don’t have to worry about stability as you would with a live probiotic. In addition, postbiotics can also be included in a formulation with virtually any other nutraceutical, which isn’t the case with many probiotics. Now, let’s focus on what makes L-92 special.
Note: Postbiotics are not measured in colony forming units (CFUs) like probiotics. The reason is, since they are not alive, they can’t form colonies. Instead, they are measured in total fluorescent units (TFUs) which identifies the total number of cells. They may also be expressed as just the total number of cells (e.g., 10 billion cells). Finally, they can be expressed as the total mg of the postbiotic material.
L-92’s Mechanisms of Action
The title of this article indicates that L-92 offers multiple benefits. This is accomplished by its various mechanisms of action, particularly how it interacts with the immune system and host cells. To begin with, L-92 influences T-helper cell responses. It can increase Th1-type activity (associated with cellular immunity) and reduce Th2-type signatures (associated with allergic responses). This helps shift the immune balance in conditions driven by excessive Th2 responses.4,5 In addition, L-92 induces apoptosis (programmed cell death) of activated CD4+ T cells. Specifically, L-92 modulates dendritic cell function, leading to increased apoptosis of antigen-stimulated T cells, especially Th2 cells, thereby dampening exaggerated immune responses (such as those associated with allergies).6 Furthermore, L-92 may enhance regulatory T cells (Tregs). In animal models, L-92 has been shown to increase CD4+CD25+Foxp3+ Treg populations and raise anti-inflammatory mediators like IL-10 and TGF-β, which can help suppress overactive immunity.7 Another mechanism worth mentioning is that components like surface layer proteins (e.g., SlpA) expressed by L-92 may help the bacteria adhere to host tissues and interact with immune cells (e.g., dendritic cells), modulating cytokine release (such as IL-10 and IL-12) that influences immune responses.8 While all of this is interesting, the real proof of the pudding is in the clinical research.
Adult Research on L-92
Allergic Rhinitis Study
In a randomized, double-blind, placebo-controlled clinical trial,9 49 patients with perennial allergic rhinitis (aka hay fever) were randomized to receive either 100 mL of heat-treated fermented milk containing L-92 (30 billion cells, n = 25) or acidified milk without lactic acid bacteria (placebo; n = 24) for eight weeks. The severity of symptoms was evaluated based on the changes in the scores of clinical symptoms. Oral administration of milk fermented with L-92 resulted in a statistically significant improvement of nasal symptom-medication scores. Ocular (eye) symptom-medication scores of patients in the L-92 intervention group tended to improve compared with those in the placebo group. In addition, clear decreases in the scores of swelling and color of the nasal mucosa were observed in the L-92 intervention group at six and eight weeks after the start of ingestion of fermented milk. These results suggest that oral administration of L-92 can alleviate the symptoms of perennial allergic rhinitis.
Japanese Cedar-pollen Allergy Study
A placebo-controlled, single-blind study10 was conducted to evaluate the effects of L-92 on the symptoms of Japanese cedar-pollen allergy. This study was carried out during the 2002 and 2003 seasons of Japanese cedar pollination. Twenty-three in-house volunteers were asked to drink 100 ml of heat-treated milk fermented with L-92 containing 50 billion cells of the bacteria, twice a day, for six consecutive weeks. A similar study was carried out during the 2003 season for 10 weeks, but the daily dose of bacteria was 20 billion cells. A significant improvement of the ocular symptom-medication score (SMS) was observed in 2002 and of the score of distress of life in 2003. These data show that a daily oral intake of not less than 20 billion cells of L-92 improved the symptoms of Japanese cedar pollinosis, thereby contributing to reduce the dose of concomitant medications.
Atopic Dermatitis Study 1
To assess effects on atopic dermatitis in adults, a double-blind, parallel-group, placebo-controlled comparison study11 was performed on 49 atopic dermatitis (AD;(aka, eczema) patients aged ≥16 years using L-92 (20.7 mg/day [about 15.32 billion cells]). Skin lesions were assessed using the SCORing AD (SCORAD) index before the start of L-92 ingestion and four and eight weeks after ingestion. Serum cytokine and blood marker levels were measured eight weeks after the start of L-92 ingestion. Results were that the group that ingested L-92 had lower SCORAD scores than the controls (p = 0.002). The L-92 group also had decreased ratios of change for eosinophil count (p = 0.03) (a white blood cell involved in allergic reactions) and increased ratios of change for serum TGF-β (p = 0.03) (a cytokine involved in immune regulation). Ratios of change for serum TGF-β rose significantly (p = 0.04) in patients showing mitigated symptoms with L-92 administration. In conclusion, administration of L-92 was effective for AD symptoms in adults. L-92 may contribute to the suppression of Th2-dominant inflammation.
Atopic Dermatitis Study 2
Another placebo-controlled, double-blind parallel-group comparison study12 was performed to evaluate the safety and efficacy of prolonged ingestion of L-92 on skin symptoms in adult AD patients. This included daily administration of L-92 (20.7 mg/day [about 15.32 billion cells]) or placebo for 24 weeks in 50 AD patients who were 16 years old or older. The severity of skin symptoms was evaluated at baseline and at four, eight, 12, 16, 20 and 24 weeks during the intervention using the investigator global assessment, eczema area and severity index, and scoring atopic dermatitis. Serum cytokine and blood marker levels were also measured at baseline and at four, eight, 16 and 24 weeks during the intervention. No adverse events were reported during the study period. Compared with the placebo group, the L-92 group showed significant decreases in investigator global assessment, eczema area and severity index, and scoring AD. Subjective symptoms in adult AD patients were reduced by L-92. Furthermore, it was suggested that sustained ingestion of L-92 resulted in suppression of scratching behavior and maintenance of remission status of skin symptoms. Sixteen weeks after the study commenced, a significant decrease in lactate dehydrogenase (i.e., a biomarker for AD) and a significant increase in transforming growth factor-β (i.e., plays a complex role in AD acting as an immunomodulator and tissue regulator) were observed in the L-92 group compared with the placebo group. In the L-92 group, a significant elevation of IL-12 (i.e., promotes inflammation in AD) level at the end of treatment period compared with before the treatment was observed. This study suggested that L-92 suppresses type-2-helper-T-cell-dominant inflammation by activating regulatory T cells and type 1 helper T cells.
Immune Study
An eight-week, randomized, double-blind, placebo-controlled, parallel-group interventional study13 was conducted to assess the effect of L-92 on systemic and intestinal immune parameters. There were 49 patients with perennial allergic rhinitis, with 25 test subjects in the L-92 group and 24 in the placebo group. The participants received 20 billion L-92 cells per day. Subjects were instructed not to change their daily routines, such as diet and sleep time, except for taking the test product at a fixed time of the day. Results were that the L-92 group showed the activation of plasmacytoid dendritic cells (i.e., rare immune cells that rapidly produce large amounts of type I interferons upon detecting viral infections, linking innate and adaptive immunity) and an improvement in local symptoms, such as cough, throat discomfort and hoarseness and subjective symptoms including fatigue, chill and lassitude during the intervention period. In conclusion, L-92 activates both intestinal and systemic immunity, alleviating typical early symptoms of viral infections in the upper respiratory tract and systemic symptoms, including the common cold. This suggests that L-92 might be a beneficial tool to enhance antiviral immunity in humans.
Child Research on L-92
Atopic Dermatitis Study
Both a preliminary casuistic study and a double-blinded, placebo-controlled study14 were conducted to investigate the complementary effects of long-term L-92 supplementation together with conventional medical therapy in the treatment of children with AD. The Atopic Dermatitis Area and Severity Index was used to evaluate AD severity while symptom severity was assessed using the symptom score. The effect of medical therapy was evaluated by adding the medication score, calculated as the sum of each product of the amount of steroid ointment used for therapy and its designated strength graded on a four-point scale, to the symptom score. The complementary effect of long-term oral administration of L-92 (30 billion CFU/day) in patients with AD was evaluated using the symptom-medication score, which was calculated as the sum of the symptom score and medication score. Both a preliminary casuistic study and a double-blinded, placebo-controlled study were performed to evaluate the effects of L-92 on the symptoms of AD in children. Results were that L-92 significantly ameliorated the symptoms of AD in Japanese children. L-92 also affected the serum concentrations of thymus and activation-regulated chemokine (i.e., a signaling protein that plays significant roles in allergic conditions like asthma and atopic dermatitis) in a time-dependent manner. In conclusion, the results of this research revealed a complementary effect of oral L-92 on the standard medical therapy (topical application of a steroid ointment) in patients with AD that was mediated, at least in part, by alterations in the Th1/Th2 balance.
Atopic Dermatitis and Food Allergy Study
Atopic dermatitis (AD) in infants is often related to food allergies (FA). To examine additional effects of two different doses of L-92 on the clinical treatment in young children afflicted by AD with diagnosed or suspected FA, a study15 was conducted in which 59 AD young children from 10 months to 3 years old, with FA or who had not started to ingest specific food(s) because of high specific IgE levels, were recruited and randomly allocated into L-92 group (daily intake of 20 mg L-92/day [about 14.8 billion cells]) and placebo group (a negligible low dose of 0.2 mg L-92 dry powder) was included. Participants were given L-92 with conventional treatment for AD over a 24-week period. The severity of eczema was evaluated using SCORing Atopic Dermatitis (SCORAD) index before intervention, and at four, 12 and 24 weeks after intervention. Results were that, after 24 weeks of intervention, a significant decrease in SCORAD was observed only in the L-92 group when compared with the baseline values. Significant decreases in thymus and activation-regulated chemokine (TARC) and total IgE were also detected 24 weeks after intake in the L-92 group compared with the placebo group. In conclusion, intake of sufficient amounts of L-92 appeared to work as an adjunctive treatment of young children afflicted by AD with diagnosed or suspected FA.
Conclusion
L-92 (distributed exclusively by Maypro) is a welcome addition to the postbiotic category. It offers applications for allergy, skin health and immune health, with solid science to support these areas of benefits. Furthermore, since the minimum dose for promoting positive effects is about 21 mg, it makes it easy to incorporate it into a single capsule rather than needing a multiple capsule dose.VR
References:
1 Postbiotic Market Expected to Reach $3 Billion by 2031—Allied Market Research. Allied Market Research. Retrieved January 22, 2026 from www.alliedmarketresearch.com/press-release/postbiotic-market.html#:~:text=The percent20postbiotic percent20market percent20was percent20valued percent20at percent20$1.6,R&D percent20to percent20explore percent20new percent20areas percent20of percent20application.
2 Postbiotics: debate continues and the ISAPP definition gains support. ISAPP. Retrieved June 19, 2024 from https://isappscience.org/postbiotics-debate-continues-and-the-isapp-definition-gains-support/.
3 Liang B, Xing D. The Current and Future Perspectives of Postbiotics. Probiotics Antimicrob Proteins. 2023;15(6):1626-1643.
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6 Kanzato H, Fujiwara S, Ise W, Kaminogawa S, Sato R, Hachimura S. Lactobacillus acidophilus strain L-92 induces apoptosis of antigen-stimulated T cells by modulating dendritic cell function. Immunobiology. 2008;213(5):399-408. doi: 10.1016/j.imbio.2007.10.001. Epub 2007 Nov 26. PMID: 18472048.
7 Shah MM, Saio M, Yamashita H, Tanaka H, Takami T, Ezaki T, Inagaki N. Lactobacillus acidophilus strain L-92 induces CD4(+)CD25(+)Foxp3(+) regulatory T cells and suppresses allergic contact dermatitis. Biol Pharm Bull. 2012;35(4):612-6. doi: 10.1248/bpb.35.612. PMID: 22466569.
8 Wakai T, Kano C, Karsens H, Kok J, Yamamoto N. Functional role of surface layer proteins of Lactobacillus acidophilus L-92 in stress tolerance and binding to host cell proteins. Biosci Microbiota Food Health. 2021;40(1):33-42. doi: 10.12938/bmfh.2020-005. Epub 2020 Sep 17. PMID: 33520567; PMCID: PMC7817507.
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11 Inoue Y, Kambara T, Murata N, Komori-Yamaguchi J, Matsukura S, Takahashi Y, Ikezawa Z, Aihara M. Effects of oral administration of Lactobacillus acidophilus L-92 on the symptoms and serum cytokines of atopic dermatitis in Japanese adults: a double-blind, randomized, clinical trial. Int Arch Allergy Immunol. 2014;165(4):247-54. doi: 10.1159/000369806. Epub 2015 Jan 31. PMID: 25660281.
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Gene Bruno, DBM, MS, RH(AHG) Professor Emeritus of Nutraceutical Science, is a writer, educator and a nutraceutical scientist with more than 45 years of experience educating natural product retailers and health care professionals and formulating natural products for dozens of dietary supplement companies. He has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications. Bruno also hosts “The Vitamin Professor Podcast” brought to you by VRM Media. He can be reached at [email protected].
