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L. CASEI 431® and immune health

Scientific studies show that L. CASEI 431® probiotic strain may support immune health

Immune health lies in the gut

70-80% of the body’s immune cells are located around the gastrointestinal tract1, where they can interact with the intestinal microbiome. Over time, a stressful lifestyle and an unhealthy diet can render the gut microflora less diverse2 – and this may negatively influence the immune health.

Certain probiotic strains may help regulate the immune response and may beneficially impact the immune function. Scientific studies show that the L. CASEI 431® strain works for example by activating immune cells, increasing the production of immune cell precursors and increasing the secretion of antibodies. 

Chr. Hansen Lactobacillus paracasei, L. CASEI 431®

The probiotic strain L. CASEI 431® has been described in more than 90 scientific publications, out of which more than 20 are publications of human clinical studies. The reports associate the probiotic strain L. CASEI 431® with support of immune health3-6 in adults and digestive health in babies7.

Scientific studies have shown that L. CASEI 431® probiotic strain may support immune health

Chr. Hansen probiotic strain L. CASEI 431® is thought to interact with the immune cells located in the gastrointestinal tract and may help your body’s immune system and promote immune responses. The strain has been investigated within immune health in four randomized, double-blinded, placebo-controlled trials of healthy adults, together including more than 1300 subjects.3-6

Three out of the four studies found that compared to placebo the L. CASEI 431® supplemented groups had a stronger immune response when the body was exposed to a challenge.3, 5, 6 In the fourth study results of a secondary endpoint showed the L. CASEI 431® supplemented group had an average reduction in the duration of respiratory tract discomforts of three days during a three week period compared to placebo4

Together with in vitro data further showing the immune regulatory effect of the L.CASEI 431® strain8, these four clinical studies have shown that L. CASEI 431® may  support immune health.

The L. CASEI 431® strain may support immune health3-6

Studies show that the L. CASEI 431® probiotic strain may:

  • impact the body’s immune defence and immune response3,5,6
  • shorten the duration of respiratory discomforts4.


Lactobacillus paracasei, L. CASEI 431® is safe for human consumption; it has been granted the QPS (Qualified Presumption of Safety) status from EFSA in Europe.9 It has been tested in human clinical studies at levels of up to at least 50 billion CFU/day, alone and in combination with Bifidobacterium, BB-12®, with no adverse events.



1 Vighi et al., Allergy and the gastrointestinal system. Clin Exp Immunol 2008; 153(Supp 1):3-6.
2 Conlon M. & Bird A., The impact of diet and lifestyle on gut microbiota and human health. Nutrients 2015;(7)17-44.
3 Rizzardini G, et al. Evaluation of the immune benefits of two probiotic strains Bifidobacterium animalis ssp. lactis, BB-12® and Lactobacillus paracasei ssp. paracasei, L. CASEI 431® in an influenza vaccination model: a randomized, double-blind, placebo-controlled study. Br J Nutr. 2012;107(6):876-84.
4 Jespersen L, et al. Effect of Lactobacillus paracasei subsp. paracasei, L. CASEI 431® on immune response to influenza vaccination and upper respiratory tract infections in healthy adult volunteers: a randomized, double-blind, placebo-controlled, parallel-group study. Am J Clin Nutr. 2015;101(6):1188-96. 
5 Trachootham, D. et al. Drinking fermented milk containing Lactobacillus paracasei 431 (IMULUSTM) improves immune response against H1N1 and cross-reactive H3N2 viruses after influenza vaccination: A pilot randomized triple-blinded placebo controlled trial. Journal of Functional Foods. 2017;33, 1–10. 
6 De Vrese, M. et al. Probiotic bacteria stimulate virus-specific neutralizing antibodies following a booster polio vaccination. European Journal of Nutrition. 2005;44(7), 406-413. 
7 Vlieger AM, et al. Tolerance and safety of Lactobacillus paracasei ssp. paracasei in combination with Bifidobacterium animalis ssp. lactis in a prebiotic-containing infant formula: a randomized controlled trial. Br J Nutr. 2009;102(6):869-75.
8 Chr. Hansen internal in vitro data on file.
9 EFSA Panel on Biological Hazards (BIOHAZ). Statement on the update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 3: Suitability of taxonomic units notified to EFSA until September 2015. EFSA Journal. 2015;13:4331.



L. CASEI 431® is a registered trademark of Chr. Hansen A/S.