Why to Eat Fermented Foods for Breast Cancer

by | Mar 21, 2023 | Breast Cancer and Nutrition, Fermented Foods | 0 comments


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Why to Eat Fermented Foods for Breast Cancer

by | Mar 21, 2023 | Breast Cancer and Nutrition, Fermented Foods | 0 comments

If you’ve been wondering whether or not fermented foods are helpful when you have (or are recovering from) breast cancer, this post is definitely for you!

In case you haven’t noticed it, there has been a huge upsurge in the prevalence of fermented foods available recently, and there are several great reasons for that which I share below.

Primarily, fermented foods are super important for our gut health because they both feed and protect the gut microbiome, which comprises one hundred trillion microorganisms and encodes more than 3 million genes, the function of most of which have yet to be determined!

This important microbiome (some like to call it our terrain) lives in our gastrointestinal tract and includes bacteria (both beneficial and not so beneficial), viruses, yeast, protozoa, fungi and other delights.

When things are running well, our gut microbiome provides us with a multitude of functions such as nutrient absorption, drug metabolism, immune system regulation, hormone regulation, modulation of nervous system signalling, and protection against pathogens, to name just a few of the more important things.

Just take a course of antibiotics without repopulating your gut with probiotics and you will soon find out how important they are. By the way, studies have reported an association between antibiotic use and cancer development, just FYI.

Eating fermented foods is one of the best ways to provide our microbiome with beneficial bacteria. Fermented foods are also amazing for breast cancer patients and survivors for 9 big reasons – and yes, you know I’m going to list them!

1. They can improve cognitive function, which often suffers as a direct result of some of the conventional treatments breast cancer patients receive;

2. Have anti-inflammatory benefits – and we know cancer is an inflammatory process;

3. Help maintain a healthy gut microbiome by feeding the good bacteria, inhibiting unfriendly pathogens, and enhancing nutrient absorption;

4. Help strengthen the immune system, 80 percent of which is located in the gut;

5. Increase a neurotransmitter known as acetylcholine which has follow-on benefits for digestive function, release of pancreatic enzymes and helps keep you regular;

6. Excellent source of vitamin C and vitamin K2;

7. Have anticancer properties – the mechanism by which fermented foods have anticancer activity varies depending upon the type of food, the phytochemical composition, type of fermentation, and microbial composition of the food. Studies have found that some of these benefits include antimutagenic (DNA protective) activity, induction of apoptosis (planned cell death, which is lacking in cancer cells), suppression of cell proliferation (rapid growth as seen in cancer cells), cell cycle arrest (stopping the rapid dividing of cancer cells) and inhibition of inflammation;

8. Naturally reduce cholesterol levels, which can also be an issue after breast cancer treatments;

9. Exert powerful effects on our emotions as well. The sour flavor of fermented foods actually helps to calm the body and the mind, according to Traditional Chinese Medicine, and helps to move stagnant liver chi (energy) out of the body.


Coconut Yogurt – It’s delicious and good for you! Coconut yogurt is a probiotic-rich product full of healthy bacteria like Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus rhamnosus, all of which are great for digestion (as well as the 9 reasons listed above).

Fermented Beets – This might be an acquired taste, but fermented beets are actually better for you than raw beets (which are awesome for cancer patients for so many reasons including building up the blood). Beets do have quite a bit of natural sugars but when fermented, most of the sugar is gobbled up by beneficial bacteria during the fermentation process.

Fermented Brown Rice – If you’re worried about things like phytic acid in standard brown rice, fermenting it gets rid of this “antinutrient” while keeping intact all of the good things about brown rice like its good benefits for the immune system, providing you with loads of vitamins and minerals, improvement of heart health and lowering cholesterol levels. Fermenting brown rice also reduces the amount of carbohydrates it contains.

Fermented Fish – Love it or hate it, fermented fish has been a staple in many cultures over thousands of years. It definitely takes a bit of courage to get it past your nose and into your mouth. However, if you can manage that, fermented fish has all of the 9 benefits listed above, including providing you with a decent serving of protein. See the proviso in the next paragraph, however.

Fish Sauce – Fish sauce contains all of the vital nutrients and minerals contained in fish including iodine, vitamins A and D, and it is enhanced by the fermentation process. One health proviso about fermented fish and fish sauce, however, would be to have it only occasionally and not daily. Due to the contamination of our ocean’s fish with heavy metals and Fukushima radiation, many consider fish and fish products to be not as healthy as they once were.

Fermented Olives – Most olives are fermented products (the exception being canned black olives) and rich in health-promoting bacteria like lactobacillus. Studies have shown that Spanish-style green olives have the most diverse array of beneficial bacteria. Olives also contain a lot of vitamin E.

Kefir – A tasty beverage created by inoculating milk (cow, camel, goat, sheep or even soy or almond milk) with bacteria, yeast cultures and kefir grains, which initiates a natural fermentation process. You can make it yourself, there are many recipes online – just make sure the kefir grains you start out with are organic.

Kimchi – A staple Korean dish, kimchi’s ingredients can include brined cabbage, radish, red pepper powder, salt, anchovy juice, green onion, garlic, sugar and ginger. It is a strong tasting dish and you either love it or hate it but it has some awesome healing powers!

Kombucha – A slightly effervescent drink made by adding specific strains of bacteria, yeast, and sugar to black or green tea, then allowing it to ferment. You can also acquire a “mother” fungus from someone (it looks a bit like a mushroom) and start your own kombucha. It can be slightly vinegary in taste but that can be tempered with the addition of other ingredients (definitely find a good recipe if making it yourself). Kombucha is full of probiotics, B vitamins, amino acids, and antioxidants. Just be cautious of mass-produced kombucha products which are probably not as healthy as they might seem and can be full of sugar.

Miso – A paste often added to Asian dishes, miso is made from fermented soybeans It is full of isoflavones like genistein and daidzein, which have potent anti-estrogenic and anticancer effects. A 2003 Japanese study found that women who had three or more servings of miso soup per day were 40 percent less likely to develop breast cancer than women who drank less than one. Miso must be organic because most soybeans are genetically modified.

Natto – Gets its name from the type of bacteria used to ferment this traditional soybean dish from Japan – Bacillus subtilis var. natto. It has a somewhat sticky texture, a pungent odor and a kind of nutty flavor. Natto contains vitamin K2, and it is full of isoflavones which make it great for breast health. Again, being derived from soybeans, it must be organic or it is more than likely GMO.

Pickles – Not the variety we usually find in the supermarket, which are really “quick pickles”. You need to look for (or create yourself) lacto-fermented pickles for pickled cucumbers to be considered a real health food. Here’s the difference: cucumbers sprinkled with salt and allowed to sit at room temperature are fermented by beneficial lactic acid bacteria that occur naturally in the environment. These bacteria destroy the organisms that would spoil the food and they improve and enrich the flavors, adding a complex tartness from lactic acid rather than the single, sharp sour note of vinegar’s acetic acid. Fermented pickles have much more nutritional power and are generally sold on refrigerated shelves.

Sauerkraut – Made from cabbage, but again, for sauerkraut to be healthy, we’re not talking about the pasteurized, canned, average grocery store variety – don’t get me wrong, that’s good for you as well, but the fermented variety has all of the super powers mentioned in this article. Buy it in the refrigerated aisle of your organic market.

Tempeh – Also made from fermented soybeans (hence must be organic), tempeh comes in the form of a cake and holds its shape a little better than tofu. It is kind of nutty in taste and absorbs other flavors easily, making it popular in Asian cooking. Considered a good meat substitute, tempeh is also full of isoflavones. A 2017 animal study found that tempeh had a significant effect on stopping the rapid growth of breast cancer cells and promoted apoptosis (planned cell death).

Tofu – Another food made from fermented soybeans (so must be purchased organic for it to be healthy), tofu can be one of those dishes you either love or hate. It’s all in how it is prepared! It comes in a big square chunk packed in water, generally, and it is super bland. But it quite easily takes on the taste of other things in the dish you’re cooking, so it can be made quite delicious. See recipe below.

Umeboshi vinegar (aka Ume Plum Vinegar) – Available in Asian food markets, this fermented vinegar has an alkalinizing effect on the body, aids digestion, aids nutrient absorption, helps diminish fatigue, and has been said to reduce the effects of chemotherapy and radiation by reducing the toxicity levels in the body.

Amazing Tofu Chili

1/4 cup plus 2 tablespoons your choice of cooking oil (I like coconut for this)
3 red onions, finely chopped
3 garlic cloves, finely minced
1-2 large Anaheim chilies, seeded and chopped
1 large red bell pepper, seeded and finely chopped
1 medium jalapeño chile, minced (optional – for a bit of heat)
1/4 cup chili powder + 4 tsp additional (set aside)
1 teaspoon ground cumin
2-3 cups of organic tomato passata or organic peeled tomatoes in juice
1 cup organic chicken stock
1/2 teaspoon dried oregano
Salt to taste
One 1 lb/ 450 gms block extra-firm tofu, drained and patted dry
1/3 cup water
1 can (15 oz/420 gms) black beans, drained
Optional: Fresh coriander/cilantro, chopped

In a large heavy cooking pot, heat 1/4 cup of the oil. Stir in the onions, garlic, chilies, bell pepper, jalapeño, chili powder and cumin and cook over medium heat, stirring occasionally, until softened but not browned. Add the tomato passata or peeled tomatoes, coarsely chopped, and the chicken stock. Stir in oregano and salt to taste. Bring mixture to a simmer over medium heat. Reduce heat and simmer, stirring occasionally, until all the vegetables are soft, around 10-12 minutes. Meanwhile dice the tofu into 1/2-inch (12 mm) pieces and pat dry. Place in a bowl and toss with the remaining 4 teaspoons chili powder. In a separate large skillet, heat the remaining 2 tablespoons oil, add the tofu and sauté over medium-high heat for 3 minutes to lightly toast the chili powder. Season with a pinch of salt. Transfer the tofu to the larger pot, add 1/3 cup of water to the skillet and scrape the bottom of the pan to loosen the browned bits. Add the liquid from the skillet to the larger pot, stir in the black beans to the chili and simmer, stirring frequently, until the flavors are blended, about 10 minutes. Optional: before serving, stir half of the coriander/cilantro into the chili; sprinkle the rest on top. This chili tastes best if it is refrigerated overnight, but if you can’t wait for that, it’s still delicious served right away.


If you are having chemotherapy or even just a course of antibiotics, because of the fact that these two are so hard on the populations of healthy gut bacteria, taking probiotics and prebiotics is crucial. Eat one serve of fermented foods daily, and take a probiotic product of at least 80-100 billion CFUs per day. The ideal time to take probiotics is before bed, when our microbiota is most active. Rotate your brand every 90 days to get the most benefit from the various strains of probiotics.


If you have SIBO (small intestine bacterial overgrowth) taking fermented foods is not advisable due to the fact that there is already an overgrowth of bacteria located in the small intestine and you wouldn’t want to add to that load.

Did you know the breast has a microbiome of its own as well? You can read more about that in this article: The Breast, Its Microbiome and Ways to Improve it.


The gut microbiome: what the oncologist ought to know – https://www.nature.com/articles/s41416-021-01467-x

Antibiotic Consumption Patterns in European Countries May Be Associated with the Incidence of Major Carcinomas – https://www.mdpi.com/2079-6382/9/10/643

Health promoting effects of fermented foods against cancer: an updated concise review – https://www.scielo.br/j/cta/a/6JnC3DcbtVp7DY7zYxGCkzk/#:~:text=Some%20studies%20indicated%20that%20the,associated%20with%20reduced%20cancer%20risk

An insight into the anticancer effects of fermented foods: A review –

Fermented dairy foods intake and risk of cancer – https://onlinelibrary.wiley.com/doi/pdf/10.1002/ijc.31959

The application of probiotic fermented milks in cancer and intestinal inflammation – https://pubmed.ncbi.nlm.nih.gov/20550747/

Fermented and nonfermented soy foods and the risk of breast cancer in a Japanese population-based cohort study – https://onlinelibrary.wiley.com/doi/full/10.1002/cam4.3677

The Link Between the Microbiota and HER2+ Breast Cancer: The New Challenge of Precision Medicine – https://www.frontiersin.org/articles/10.3389/fonc.2022.947188/full#B15

Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis – https://www.hindawi.com/journals/omcl/2021/9081738/

Oral administration of milk fermented by Lactobacillus casei CRL431 was able to decrease metastasis from breast cancer in a murine model by modulating immune response locally in the lungs – https://www.sciencedirect.com/science/article/abs/pii/S175646461930026X?via%3Dihub

Impact of Fermented Foods on Human Cognitive Function—A Review of Outcome of Clinical Trials – https://www.mdpi.com/2218-0532/86/2/22

Modulation of CYP1A1, CYP1A2 and CYP1B1 Expression by Cabbage Juices and Indoles in Human Breast Cell Lines – https://pubmed.ncbi.nlm.nih.gov/22716309/

Article: Sauerkraut consumption may fight off breast cancer –

Article: Miso a day keeps breast cancer away – https://www.japantimes.co.jp/news/2003/06/19/national/miso-a-day-keeps-breast-cancer-away/

Article: Fermented Foods and Gastric Cancer Prevention – https://pearlpoint.org/fermented-foods-and-gastric-cancer-prevention/


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About Marnie Clark

marnie clark breast cancer coach

Hi I’m Marnie Clark, breast cancer survivor turned coach. I have 20 years of experience in natural medicine.  In 2004/05 I battled breast cancer myself. You can see more about my journey on my page Breast Cancer Diary.

I’ve been healthy and recurrence-free since 2004 and in 2012 I became a Breast Cancer Coach because I became aware of the fact that whilst there is now a wealth of information on the Internet, much of it is confusing, conflicting, and sometimes just wrong!

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