Probiotics (including Qiara) don't help prevent or treat breast inflammation

Probiotics (for example, containing Lactobacillus fermentum (‘Qiara’) and Lactobacillus salivarius) are commonly recommended for lactating women who have breast inflammation.

Probiotics are claimed to outcompete pathogenic bacteria in human milk, and to restore and maintain healthy balance of the microbiome, either for prevention of or treatment of lactation-related breast inflammation.

But there is no reliable evidence that probiotics are effective for either the prevention of or treatment of mastitis, and no convincing physiological rationale.

For example, a close analysis of a 2024 review which investigates the association between what the authors call Lactational Infective Mastitis and the milk microbiome does not alter the conclusion that there is no reliable evidence supporting the use of probiotics for mastitis.

You can find an analysis of existing studies which investigate probiotics and breast inflammation here.

Acknowledgements

The image on this page is of Lactobacillus bacteria.

Selected references

Amir LH, Griffin L, Cullinane M, Garland SM. Probiotics and mastitis: evidence-based marketing? International Breastfeeding Journal. 2016;111(19):doi:10.1186/s13006-13016-10078-13005.

Barker M, Adelson P, Peters MDJ, Steen M. Probiotics and human lactational mastitis: a scoping review. Women and Birth. 2020;d33:e483-e491.

Crepinsek MA, Taylor EA, Michener K, Stewart F. Interventions for preventing mastitis after childbirth. Cochrane Database of Systematic Reviews. 2020(9):CD007239.

Jimenez E, Manzano S, Schlembach D. Ligilactobacillus salivarius PS2 supplementation during pregnancy and lactation prevents mastitis: a randomised controlled trial. Microorganisms. 2021;9(1933):https://doi.org/10.3390/microorganisms9091933.

Saifi F, Jeoboam B, Beckler MD, Costin JM. The association between Lactational Infective Mastitis and the microbiome: development, onset, and treatments. Cureus. 2024:DOI: 10.7759/cureus.62717.

Simpson MR, Avershina E, Sstorre O, Johnsen R, Rudi K, Oien T. Breastfeeding-associated microbiota in human milk following supplementation with Lactobacillus rhamnosus GG, Lactobacillus acidophilus La-5, and Bifidobacterium animalis ssp. lactis Bb-12. Journal of Diary Science. 2018;101(2):889-899.

Yu Q, Xu C, Wang M. The preventive and therapeutic effects of probiotics on mastitis: a systematic review and meta-analysis. Plos One. 2022;17(9):e0274467.