What’s the Gut Got to Do with Breast Cancer? Firstly, your gut is sometimes called the second brain.1 There are more nerve signal going from the gut to the brain than from the brain to the gut. The GI tract is colonized with billions of microbes called the microbiota that play a role in your overall health. Therefore, they can aid your health or hijack it and take where you don’t want to go.

The community of gut bugs can make or break you; and your diet influences which microbes grow and which ones die. 2If you served burgers, fries, pizza, chips, beer and soda you will attract a different crowd than if you served vegetables, fruit, lean protein and nuts and seeds. The problem is that the microbes attracted to fast, fatty, sugary or processed starchy foods can hijack your hormone system, your immune system and your nervous system and derail your overall health.

For instance, about 3.5 million women are diagnosed with breast cancer each year and it is the most frequent cancer in the female population. An interesting fact is that healthy breast tissue has been found to be mostly enriched with bacteria of the phyla Proteobacteria, Firmicutes and Actinobacteria. bacteria such as Lactococcus spp. are increased in the breast tissues of healthy women compared to the cancerous tissues of BC women and may therefore have potential protective effects against BC.

A presence of abnormal gut microbes has been linked to breast cancer because these microbes can alter the metabolism of estrogen to a more toxic form and it is proposed that probiotics and altering the gut microbiota may be able to prevent or manage breast cancer. 3,4 Breast cancer is associated with a distinct microbiome and this microbiome may alter the response to therapy or be used as a diagnostic tool or biomarker for diagnosing and staging breast cancer. 5

Furthermore, knowing this give a lot of control. Feeding the microbiome that favors healthy breast tissue requires a diet that supports it.

Feeding Supportive Microbiome

  • Eat more probiotic foods such as sauerkraut, kombucha, yogurt, kefir, kimchi, and foods that contain probiotic cultures.
  • Eat mostly plants that are nutrient rich and support a healthy microbiome.6
  • Avoid sugar, processed foods and too much saturated fat.
  • Avoid excessive use of antibiotics and steroids.
  • Take a probiotic.
  • Manage your stress
  • Avoid foods that can cause inflammation. Although, this is individualized and is best determined through doing an elimination diet and/or food sensitivity testing.
  • Exercise in green spaces. Exposure to soil and nature increases the diversity of your microbiome. 7
  • Gut microbiota is transmitted from the mother to the child through breast feeding and vaginal delivery and may affect immunity later in life. The immune system guards against cancer. 8

A healthy gut and healthy microbiome are essential to not only prevent or manage breast cancer but it is involved in modulating many conditions. Eating healthy plant based foods and a Mediterranean style diet, exercising, restful sleep and managing stress can alter your microbiome in a positive way that supports health and wellbeing. If you need assistance in determining the health of your microbiome and supporting it, apply for a free, no obligation clarity call to see if we are a good fit.


  1. Ochoa-Repáraz J, Kasper LH. The Second Brain: Is the Gut Microbiota a Link Between Obesity and Central Nervous System Disorders? Curr Obes Rep. 2016;5(1):51-64. doi:10.1007/s13679-016-0191-1
  2. Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI. The Effect of Diet on the Human Gut Microbiome: A Metagenomic Analysis in Humanized Gnotobiotic Mice. Sci Transl Med. 2009;1(6):6ra14. doi:10.1126/scitranslmed.3000322
  3. Feng ZP, Xin HY, Zhang ZW, et al. Gut microbiota homeostasis restoration may become a novel therapy for breast cancer. Invest New Drugs. 2021;39(3):871-878. doi:10.1007/s10637-021-01063-z
  4. Chen J, Douglass J, Prasath V, et al. The microbiome and breast cancer: a review. Breast Cancer Res Treat. 2019;178(3):493-496. doi:10.1007/s10549-019-05407-5
  5. Fernández MF, Reina-Pérez I, Astorga JM, Rodríguez-Carrillo A, Plaza-Díaz J, Fontana L. Breast Cancer and Its Relationship with the Microbiota. Int J Environ Res Public Health. 2018;15(8):1747. doi:10.3390/ijerph15081747
  6. Dahl WJ, Rivero Mendoza D, Lambert JM. Diet, nutrients and the microbiome. Prog Mol Biol Transl Sci. 2020;171:237-263. doi:10.1016/bs.pmbts.2020.04.006
  7. Robinson JM, Breed MF. Green Prescriptions and Their Co-Benefits: Integrative Strategies for Public and Environmental Health. Challenges. 2019;10(1):9. doi:10.3390/challe10010009
  8. Tasnim N, Abulizi N, Pither J, Hart MM, Gibson DL. Linking the Gut Microbial Ecosystem with the Environment: Does Gut Health Depend on Where We Live? Front Microbiol. 2017;8. Accessed October 16, 2022. https://www.frontiersin.org/articles/10.3389/fmicb.2017.01935