Guest post by Dr Laura Villa; Image by edwina_mc from Pixabay 

The foods that help keep your gut healthy

What are fermented foods?

Historically, food fermentation was implemented as a method of preservation.

Additionally, fermentation enhances the taste and texture of some foods, such as olives.

Not only does it improve the shelf-life and taste, but it can give your body a dose of healthful probiotics, which are microorganisms essential for optimal digestion.

Fermentation occurs in the absence of oxygen and in the presence of beneficial microorganisms (yeasts, mold, and bacteria) that obtain their energy through fermentation. During fermentation, the beneficial microbes break down sugars and starches into alcohol and acids, making food more nutritious and preserving it to go longer without spoiling. For example, starches and sugars in vegetables are converted to lactic acid, and the lactic acid acts as a natural preservative. 

There are two main methods of fermenting foods. Foods can be fermented naturally, whereby organisms are present naturally in the raw food or processing environment, for example, sauerkraut, kimchi, and certain soy products. Alternatively, fermentation can occur using a starter culture, for instance, refi, kombucha, and natto. 

There are many different types of fermented foods, including:

    • Cultured milk and yogurt: Made from fermenting milk with a starter culture of bacteria.
    • Miso: This is a Japanese paste made from soybeans. 
    • Kimchi: This is similar to sauerkraut and is made from fermented cabbage and other vegetables. 
    • Sauerkraut: This is fermented cabbage. It is high in fiber as well as many vitamins.
    • Kombucha: This is a fizzy drink made from fermenting black tea. 
    • Tempeh: Similar to miso, this is made from soybeans and is a goods source of protein. 
    • Natto: A Japanese food consisting of fermented soybeans.
    • Sourdough bread 
    • Kefir: A probiotic cultured drink that contains multiple strains of bacteria and yeast. It is rich in minerals and vitamins. 

What are the benefits of fermented foods?

Research now shows that diets that incorporate regular intake of fermented foods can bring several benefits.

Improves digestion and absorption. Through the fermentation process, sugars and starches are brown down, making them easier to digest. Fermentation products provide enzymes necessary for digestion. 

Help restore your gut after antibiotics. Antibiotics wipe out good and bad bacteria. During the fermentation process, probiotics are produced and help restore the balance of friendly bacteria.

Boots your immune system. The bacteria that are in your gut play an essential role in your immune system. The high probiotic content can give your immune system a boost. Further, fermented foods are often high in vitamin C and zinc, crucial for immune function.

Provide nutrients. Many fermented foods provide high levels of vitamin B12, vitamin A, vitamin C, calcium, magnesium, vitamin K2, and biotin.

Improves mental health. Depression and anxiety are often associated with gut problems, suggesting a link between mental health and gut function. (Click here and here for more on this.)

The bottom line

Fermentation helps increase the shelf life of foods.

Probiotics found in fermented foods may improve digestion, immunity, nutrient status, and mental health.


  1. Heart Foundation NZ. What are the benefits of fermented foods? Heart Foundation NZ. Published August 20, 2018. Accessed December 3, 2020.
  2. Stiemsma LT, Nakamura RE, Nguyen JG, Michels KB. Does Consumption of Fermented Foods Modify the Human Gut Microbiota? The Journal of nutrition. 2020;150(7):1680-1692. doi:10.1093/jn/nxaa077
  3. Dimidi E, Cox SR, Rossi M, Whelan K. Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Nutrients. 2019;11(8):1806. Published 2019 Aug 5. doi:10.3390/nu11081806
  4. Publishing HH. Fermented foods can add depth to your diet. Harvard Health. Accessed December 4, 2020.
  5. Scientists, F., 2020. Fermented Foods – International Scientific Association For Probiotics And Prebiotics (ISAPP). [online] International Scientific Association for Probiotics and Prebiotics (ISAPP). Available at: <> [Accessed 4 December 2020].
  7. Melini F, Melini V, Luziatelli F, Ficca AG, Ruzzi M. Health-Promoting Components in Fermented Foods: An Up-to-Date Systematic Review. Nutrients. 2019;11(5):1189. Published 2019 May 27. doi:10.3390/nu11051189
  8. Aslam H, Green J, Jacka FN, et al. Fermented foods, the gut and mental health: a mechanistic overview with implications for depression and anxiety. Nutr Neurosci. 2020;23(9):659-671. doi:10.1080/1028415X.2018.1544332