Breastfeeding biology, milk bioactive components, and probiotics as cancer-relevant mechanisms influencing maternal psychological wellbeing
Abstract
Breastfeeding is a complex psychobiological process involving hormonal regulation, immune modulation, microbial transfer, and the activity of diverse bioactive components, all of which have implications for maternal health and cancer-relevant pathways. Evidence indicates that lactational hormones such as prolactin and oxytocin, together with breast milk constituents including immunoglobulins, lactoferrin, cytokines, antioxidants, and commensal microbes, participate in anti-inflammatory, antioxidant, and endocrine-regulatory mechanisms associated with reduced cancer risk in mothers. Probiotics may further enhance these processes by influencing maternal gut microbiota, improving immune resilience, and potentially modulating pathways implicated in carcinogenesis. Beyond these biological interactions, mothers frequently encounter cancer-related information through clinical, digital, and social channels, shaping psychological responses that influence breastfeeding behaviors, risk perception, and emotional wellbeing. Some mothers derive reassurance from perceived protective effects of breastfeeding, while others experience heightened anxiety, confusion, or pressure to breastfeed due to incomplete or conflicting information. Integrating biological and psychological perspectives is therefore essential within psycho-oncology to support informed decision-making, reduce misinformation-driven distress, and promote healthier maternal experiences. This narrative review synthesizes current evidence on breastfeeding biology, bioactive milk components, probiotic effects, and cancer-associated mechanisms, while examining the psychological implications for mothers and outlining communication strategies for clinicians and public health practitioners. By bridging physiological pathways with maternal emotional experiences, the review aims to inform more effective, empathetic, and evidence-based approaches to supporting breastfeeding women.
Copyright (c) 2026 Huiqin Qian, Ying Wang, Yuping Hu
This work is licensed under a Creative Commons Attribution 4.0 International License.
References
1. Garwolińska D, Namieśnik J, Kot-Wasik A, et al. Chemistry of human breast milk—A comprehensive review of the composition and role of milk metabolites in child development. Journal of Agricultural and Food Chemistry. 2018; 66(45): 11881–11896. doi: 10.1021/acs.jafc.8b04031
2. Lokossou GAG, Kouakanou L, Schumacher A, et al. Human breast milk: From food to active immune response with disease protection in infants and mothers. Frontiers in Immunology. 2022; 13. doi: 10.3389/fimmu.2022.849012
3. Simpson MR, Avershina E, Storrø O, et al. 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 Dairy Science. 2018; 101(2): 889–899. doi: 10.3168/jds.2017-13411
4. Franca-Botelho ADC, Ferreira MC, Franca JL, et al. Breastfeeding and its relationship with reduction of breast cancer: A review. Asian Pacific Journal of Cancer Prevention. 2012; 13(11): 5327–5332. doi: 10.7314/apjcp.2012.13.11.5327
5. Redondo CM, Gago-Domínguez M, Ponte SM, et al. Breast feeding, parity and breast cancer subtypes in a Spanish cohort. PloS One. 2012; 7(7): e40543. doi: 10.1371/journal.pone.0040543
6. Jefferson UT. Support interventions to address breastfeeding challenges. Western Journal of Nursing Research. 2018; 40(8): 1107–1109. doi: 10.1177/0193945918770746
7. Collado MC, Delgado S, Maldonado A, et al. Assessment of the bacterial diversity of breast milk of healthy women by quantitative real-time PCR. Letters in Applied Microbiology. 2009; 48(5): 523–528. doi: 10.1111/j.1472-765x.2009.02567.x
8. Liu W, Chen M, Duo L, et al. Characterization of potentially probiotic lactic acid bacteria and bifidobacteria isolated from human colostrum. Journal of Dairy Science. 2020; 103(5): 4013–4025. doi: 10.3168/jds.2019-17602
9. Andreas NJ, Kampmann B, Mehring Le-Doare K. Human breast milk: A review on its composition and bioactivity. Early Human Development. 2015; 91(11): 629–635. doi: 10.1016/j.earlhumdev.2015.08.013
10. Zivkovic AM, German JB, Lebrilla CB, et al. Human milk glycobiome and its impact on the infant gastrointestinal microbiota. Proceedings of the National Academy of Sciences. 2010; 108(supplement_1): 4653-4658. doi: 10.1073/pnas.1000083107
11. Yi D, Kim S. Human breast milk composition and function in human health: From nutritional components to microbiome and micrornas. Nutrients. 2021; 13(9): 3094. doi: 10.3390/nu13093094
12. Ancona P, Bergamini CM, Ferrari C, et al. From lactation to malignancy: A comparison between healthy and cancerous breast gland at single‐cell resolution reveals new issues for tumorigenesis. FEBS Letters. 2025; 599(21): 3124–3149. doi: 10.1002/1873-3468.70162
13. Chowdhury R, Sinha B, Sankar MJ, et al. Breastfeeding and maternal health outcomes: A systematic review and meta‐analysis. Acta Paediatrica. 2015; 104(S467): 96–113. doi: 10.1111/apa.13102
14. World Health Organization. SESSION 2 -The physiological basis of breastfeeding. In: Infant and Young Child Feeding. WHO Press; 2009.
15. Tworoger, Shelley S, Hankinson SE. Prolactin and Breast Cancer Risk. Cancer Letters. 2006; 243(2): 160–169. doi: 10.1016/j.canlet.2006.01.032
16. Daz L, Daz M, Gonzlez L, et al. Prolactin in the Immune System. In: Prolactin. InTech; 2013.
17. Levina VV, Nolen B, Su Y, et al. Biological significance of prolactin in gynecologic cancers. Cancer Research. 2009; 69(12): 5226–5233. doi: 10.1158/0008-5472.can-08-4652
18. Dinleyici M, Barbieur J, Dinleyici EC, et al. Functional effects of human milk oligosaccharides (HMOs). Gut Microbes. 2023; 15(1). doi: 10.1080/19490976.2023.2186115
19. Rousseaux A, Brosseau C, Le Gall S, et al. Human milk oligosaccharides: Their effects on the host and their potential as therapeutic agents. Frontiers in Immunology. 2021; 12. doi: 10.3389/fimmu.2021.680911
20. Okburan G, Kızıler S. Human milk oligosaccharides as prebiotics. Pediatrics & Neonatology. 2023; 64(3): 231–238. doi: 10.1016/j.pedneo.2022.09.017
21. Donald K, Petersen C, Turvey SE, et al. Secretory IgA: Linking microbes, maternal health, and infant health through human milk. Cell Host & Microbe. 2022; 30(5): 650–659. doi: 10.1016/j.chom.2022.02.005
22. Pan S, Weng H, Hu G, et al. Lactoferrin may inhibit the development of cancer via its immunostimulatory and immunomodulatory activities. International Journal of Oncology. 2021; 59(5). doi: 10.3892/ijo.2021.5265
23. Norrgrann M, Hörnfeldt M, Latheef F, et al. Lipid peroxidation and antioxidative capacity are unaltered in transitional breast milk exposed to light from women giving birth to preterm infants before 32 weeks of gestation. Nutrients. 2023; 15(12): 2818. doi: 10.3390/nu15122818
24. Aycicek A, Erel O, Kocyigit A, et al. Breast milk provides better antioxidant power than does formula. Nutrition. 2006; 22(6): 616–619. doi: 10.1016/j.nut.2005.12.011
25. Cortes-Macías E, Selma-Royo M, García-Mantrana I, et al. Maternal diet shapes the breast milk microbiota composition and diversity: Impact of mode of delivery and antibiotic exposure. Journal of Nutrition. 2021; 151(2): 330–340. doi: 10.1093/jn/nxaa310
26. Rebello SJ, Kurian C, Desai SP, et al. A comprehensive review of breast milk microbiome: Its impact on infant health and disease management. Journal of Pure and Applied Microbiology. 2025; 19(2): 902–913. doi: 10.22207/jpam.19.2.51
27. Jost T, Lacroix C, Braegger CP, et al. Vertical mother–neonate transfer of maternal gut bacteria via breastfeeding. Environmental Microbiology. 2014; 16(9): 2891–2904. doi: 10.1111/1462-2920.12238
28. Soto A, Martín V, Jiménez E, et al. Lactobacilli and bifidobacteria in human breast milk. Journal of Pediatric Gastroenterology and Nutrition. 2014; 59(1): 78–88. doi: 10.1097/mpg.0000000000000347
29. Pärnänen K, Karkman A, Hultman J, et al. Maternal gut and breast milk microbiota affect infant gut antibiotic resistome and mobile genetic elements. Nature Communications. 2018; 9(1). doi: 10.1038/s41467-018-06393-w
30. Milani C, Mancabelli L, Lugli GA, et al. Exploring vertical transmission of bifidobacteria from mother to child. Applied and Environmental Microbiology. 2015; 81(20): 7078–7087. doi: 10.1128/aem.02037-15
31. Sakwinska O, Moine D, Delley M, et al. Microbiota in breast milk of Chinese lactating mothers. PLoS One. 2016; 11(8): e0160856. doi: 10.1371/journal.pone.0160856
32. Drago L, Toscano M, De Grandi R, et al. Microbiota network and mathematic microbe mutualism in colostrum and mature milk collected in two different geographic areas: Italy versus Burundi. The ISME Journal. 2016; 11(4): 875–884. doi: 10.1038/ismej.2016.183
33. Hermansson H, Kumar H, Collado MC, et al. Breast milk microbiota is shaped by mode of delivery and intrapartum antibiotic exposure. Frontiers In Nutrition. 2019; 6. doi:10.3389/fnut.2019.00004
34. Van den Elsen LWJ, Garssen J, Burcelin R, et al. Shaping the gut microbiota by breastfeeding: The gateway to allergy prevention? Frontiers in Pediatrics. 2019; 7. doi: 10.3389/fped.2019.00047
35. Taheri A, Raeisi T, Darand M, et al. Effects of pre/probiotic supplementation on breast milk levels of tgf-b1, tgf-b2, and iga: A systematic review and meta-analysis of randomized-controlled trial. Breastfeeding Medicine. 2022; 17(1): 22–32. doi: 10.1089/bfm.2021.0204
36. Alemu BK, Azeze GG, Wu L, et al. Effects of maternal probiotic supplementation on breast milk microbiome and infant gut microbiome and health: a systematic review and meta-analysis of randomized controlled trials. American Journal of Obstetrics & Gynecology MFM. 2023; 5(11): 101148. doi: 10.1016/j.ajogmf.2023.101148
37. Martín V, Maldonado-Barragán A, Moles L, et al. Sharing of bacterial strains between breast milk and infant feces. Journal of Human Lactation. 2012; 28(1): 36–44. doi: 10.1177/0890334411424729
38. Hamamah S, Lobiuc A, Covasa M. Antioxidant role of probiotics in inflammation-induced colorectal cancer. International Journal of Molecular Sciences. 2024; 25(16): 9026. doi: 10.3390/ijms25169026
39. Naeem H, Hassan HU, Shahbaz M, et al. Role of probiotics against human cancers, inflammatory diseases, and other complex malignancies. Journal of Food Biochemistry. 2024; 2024(1): 6632209. doi: 10.1155/2024/6632209
40. Treven P, Mrak V, Bogovič Matijašić B, et al. Administration of probiotics Lactobacillus rhamnosus GG and Lactobacillus gasseri K7 during pregnancy and lactation changes mouse mesenteric lymph nodes and mammary gland microbiota. Journal of Dairy Science. 2015; 98(4): 2114–2128. doi: 10.3168/jds.2014-8519
41. Kearns R. Gut modulation to regulate NF-κB in colorectal and gastric cancer therapy and inflammation. Cancer Immunology, Immunotherapy. 2025; 74(8): 264. doi: 10.1007/s00262-025-04118-9
42. Dai Z, Wu Z, Hang S, et al. Amino acid metabolism in intestinal bacteria and its potential implications for mammalian reproduction. Molecular Human Reproduction. 2015; 21(5): 389–409. doi: 10.1093/molehr/gav003
43. Ribeiro CM, Vieira TRR. Probiotics and the gut–brain connection on microbial pathways supporting mental well-being - a systematic review. Microbial Biotechnology. 2025; 8(1): 1–8. doi: 10.25163/microbbioacts.8110470
44. Babic A, Sasamoto N, Rosner BA, et al. Association between breastfeeding and ovarian cancer risk. JAMA Oncology. 2020; 6(6): e200421. doi: 10.1001/jamaoncol.2020.0421
45. Jordan SJ, Na R, Johnatty SE, et al. Breastfeeding and endometrial cancer risk. Obstetrics & Gynecology. 2017; 129(6): 1059–1067. doi: 10.1097/aog.0000000000002057
46. Pajai S, Gupta S, Pawade AA. Benefits of breastfeeding on child and postpartum psychological health of the mother. Journal of South Asian Federation of Obstetrics and Gynaecology. 2023; 15(2): 218–222. doi: 10.5005/jp-journals-10006-2217
47. Kotsopoulos J, Lubinski J, Salmena L, et al. Breastfeeding and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers. Breast Cancer Research. 2012; 14(2). doi: 10.1186/bcr3138
48. Li DP, Du C, Zhang ZM, et al. Breastfeeding and ovarian cancer risk: A systematic review and meta-analysis of 40 epidemiological studies. Asian Pacific Journal of Cancer Prevention. 2014; 15(12): 4829–4837. doi: 10.7314/apjcp.2014.15.12.4829
49. Boundy EO, Nelson JM, Li R. Public belief in the maternal health benefits of breastfeeding—United States, 2018 and 2021. Preventing Chronic Disease. 2023; 20: 230010. doi: 10.5888/pcd20.230010
50. Huo D, Adebamowo CA, Ogundiran TO, et al. Parity and breastfeeding are protective against breast cancer in Nigerian women. British Journal of Cancer. 2008; 98(5): 992–996. doi: 10.1038/sj.bjc.6604275
51. Costantini C, Joyce A, Britez Y. Breastfeeding experiences during the COVID-19 lockdown in the United Kingdom: An exploratory study into maternal opinions and emotional states. Journal of Human Lactation. 2021; 37(4): 649–662. doi: 10.1177/08903344211026565
52. Grummer-Strawn LM, Holliday F, Jungo KT, et al. Sponsorship of national and regional professional paediatrics associations by companies that make breast-milk substitutes: evidence from a review of official websites. BMJ Open. 2019; 9(8): e029035. doi: 10.1136/bmjopen-2019-029035
53. Gómez L, Verd S, de-la-Banda G, et al. Perinatal psychological interventions to promote breastfeeding: a narrative review. International Breastfeeding Journal. 2021; 16(1): 8. doi: 10.1186/s13006-020-00348-y
54. Perrine CG, Scanlon KS, Li R, et al. Baby-friendly hospital practices and meeting exclusive breastfeeding intention. Pediatrics. 2012; 130(1): 54–60. doi: 10.1542/peds.2011-3633
55. Kasem A, Abuhammad S, Alswaiti EMS. Maternal awareness of breastfeeding policies in baby‐friendly hospitals in Jordan. Nursing Forum. 2022; 57(5): 843–850. doi: 10.1111/nuf.12731
56. Nabatanzi M, Seruwagi GK, Tushemerirwe FB, et al. “Mine did not breastfeed”, mothers’ experiences in breastfeeding children aged 0 to 24 months with oral clefts in Uganda. BMC Pregnancy Childbirth. 2021; 21(1): 100. doi: 10.1186/s12884-021-03581-3
57. Ingram J. A mixed methods evaluation of peer support in Bristol, UK: Mothers’, midwives’ and peer supporters’ views and the effects on breastfeeding. BMC Pregnancy and Childbirth. 2013; 13(1). doi: 10.1186/1471-2393-13-192
58. Odom EC, Li R, Scanlon KS, et al. Reasons for Earlier Than Desired Cessation of Breastfeeding. Pediatrics. 2013; 131(3): e726–e732. doi: 10.1542/peds.2012-1295
59. Hobbs AJ, Mannion CA, McDonald SW, et al. The impact of caesarean section on breastfeeding initiation, duration and difficulties in the first four months postpartum. BMC Pregnancy and Childbirth. 2016; 16(1). doi: 10.1186/s12884-016-0876-1
60. Smorti M, Testa I, Gallese M, et al. Protect, promote and support: A warm chain of breastfeeding for oncological women—results from a survey of young Italian cancer mothers. ecancermedicalscience. 2020; 14. doi: 10.3332/ecancer.2020.1151
61. Schwarz EB, Hoyt-Austin A, Fix M, et al. Prenatal Counseling on the maternal health benefits of lactation: A randomized trial. Breastfeeding Medicine. 2024; 19(1): 52–58. doi: 10.1089/bfm.2023.0219
62. Ganju A, Suresh A, Stephens J, et al. Learning, life, and lactation: Knowledge of breastfeeding’s impact on breast cancer risk reduction and its influence on breastfeeding practices. Breastfeeding Medicine. 2018; 13(10): 651–656. doi: 10.1089/bfm.2018.0170
63. Liu H, Gruber CW, Alewood PF, et al. The oxytocin receptor signaling system and breast cancer: A critical review. Oncogene. 2020; 39(37): 5917–5932. doi: 10.1038/s41388-020-01415-8
64. Stuebe AM, Willett WC, Xue F, et al. Lactation and Incidence of Premenopausal Breast Cancer. Archives of Internal Medicine. 2009; 169(15): 1364. doi: 10.1001/archinternmed.2009.231
65. Fortner RT, Sisti J, Chai B, et al. Parity, breastfeeding, and breast cancer risk by hormone receptor status and molecular phenotype: results from the Nurses’ Health Studies. Breast Cancer Research. 2019; 21(1). doi: 10.1186/s13058-019-1119-y
66. Ambrosone CB, Zirpoli G, Ruszczyk M, et al. Parity and breastfeeding among African-American women: Differential effects on breast cancer risk by estrogen receptor status in the women’s circle of health study. Cancer Causes & Control. 2014; 25(2): 259–265. doi: 10.1007/s10552-013-0323-9
67. Ma H, Wang Y, Sullivan-Halley J, et al. Breast cancer receptor status: Do results from a centralized pathology laboratory agree with seer registry reports? Cancer Epidemiology, Biomarkers & Prevention. 2009; 18(8): 2214–2220. doi: 10.1158/1055-9965.EPI-09-0301
68. Katsouyanni K, Lipworth L, Trichopoulou A, et al. A case-control study of lactation and cancer of the breast. British Journal of Cancer. 1996; 73(6): 814–818. doi: 10.1038/bjc.1996.143
69. Salsabila H, Sukmawati D, Iswanti FC. Innate and adaptive immune components in human breast milk and their role in early-life immunity. Biomedical Journal of Indonesia. 2025; 11(3): 151–159. doi: 10.32539/bji.v11i3.272
70. Modak A, Ronghe V, Gomase K P, et al. The psychological benefits of breastfeeding: fostering maternal well-being and child development. Cureus. 2023; 15(10). doi: 10.7759/cureus.46730
71. Ramírez-Rico G, Drago-Serrano ME, León-Sicairos N, et al. Lactoferrin: A nutraceutical with activity against colorectal cancer. Frontiers in Pharmacology. 2022; 13. doi: 10.3389/fphar.2022.855852
