Do Eating Fermented Foods Boost Immunity?

Does Eating Fermented Foods Boost Immunity?

Fermented foods can ease the symptoms you feel in your gut.
Here's why:

The symptoms you feel in your gut are caused by your unbalanced immune system producing too much inflammation. In order to balance your immunity and reduce inflammation in your gut, it is important to restore balance to the helpful bacteria that live in your gut. Those helpful bacteria come in hundreds of different types and have many functions including helping you digest, unlocking nutrients in foods, and maintaining a healthy immune system. 1 Restoring balance to the huge ecosystem of helpful bacteria in your gut requires eating helpful bacteria. 2,3,4 The best source of those helpful bacteria is from fermented foods such as sauerkraut, yogurt, or kombucha. These foods are such a good source of helpful bacteria because the fermentation process allows for a diverse collection of helpful bacteria to multiply and grow on the foods. When we eat these fermented foods, those helpful bacteria then begin living in our gut where they help maintain a healthy immune system.
The best fermented foods are made at home.

If you are interested in fermenting your own food, I suggest buying Sandor Katz’s book The Art of Fermentation for more information on how to ferment a wide variety of foods.

Where can I buy Fermented Foods?

The best place to get your fermented foods is from your own home. Eating food that you ferment yourself will ensure that you are getting the largest diversity of helpful bacteria possible.

If you do choose to ferment your own foods, do not can your fermented foods. The canning process kills all the helpful bacteria in your fermented foods.

Fortunately, there are some fermented food products available at the grocery store.

In the grocery store, look for fermented products that are unpasteurized, that use a SCOBY (symbiotic culture of bacteria and yeast) and/or that list many different types of helpful bacteria in the product.

A few examples of these products are provided at the end of this packet. Alternatively, ask your local farmers about any fermented products they may sell.

Fermented Foods at Home vs Mass-Produced Fermentation

Traditionally, foods get fermented when we allow helpful bacteria to break down food in a controlled environment. This fermentation process allows a diverse collection of helpful bacteria to grow on the food. When we eat these foods, those helpful bacteria begin living in our gut where they help us digest foods, unlock nutrients in foods, and maintain a healthy immune system.

The process of industrially producing fermented foods reduces the diversity and number of helpful bacteria in those foods. In this industrialized process, foods are first fermented then heated up to kill all the helpful bacteria in the food (aka pasteurized) and then packaged. These steps are taken to increase shelf life. Sometimes after heating, the foods are injected with a selection of a couple helpful bacteria for health benefits. However, using only a couple of different types of helpful bacteria means those foods have less diversity of helpful bacteria than traditionally fermented foods. This reduction in diversity makes industrially produced fermented foods less effective in restoring balance to the helpful bacteria in your gut and, ultimately, less effective in easing your gut symptoms.

Fermented products at the grocery store that are unpasteurized, that do not use preservatives, that use a SCOBY, and/or that list the many helpful bacteria in the product are more likely to contain a large diversity of helpful bacteria. Even better, foods fermented at home or by your local farmers contain a huge diversity of helpful bacteria.

Food Allergy and Fermentation

In addition to helping maintain a healthy immune system, eating fermented foods can also reduce your risk of eating something that gives you an allergic reaction. When most foods ferment, the part of the food that causes allergic reactions is broken down.5,6 So, you may be allergic to milk or cabbage, but you still may be able to eat yogurt or sauerkraut without experiencing allergic symptoms.

Probiotic Supplements and food options can be found at your local grocery store.

Probiotic supplements contain a selection of a few types of helpful bacteria. While these pills can be useful in certain situations, even the best probiotic supplements only contain a few different types of helpful bacteria while a healthy human gut contains hundreds of types of helpful bacteria. Due to this lack of diversity in probiotic pills, eating fermented foods containing a large diversity of helpful bacteria can be more effective in restoring the balance of helpful bacteria in your gut.

We've assembled a list of ways that can help you identify what to avoid and what to buy.

  • Look for a list of helpful bacteria.
  • If allergic to dairy, try milk kefir alternatives.
  • Look for Kombucha that utilizes SCOBY.
  • Look for foods that are unpasteurized.
  • Check for ingredients you may be allergic to such as wheat proteins.
  • Check that there are no preservatives in the ingredients list.

Both diary and non-dairy alternatives are available for those interested in kefir.

Examples of Common Fermented Foods

  • Saurekraut
  • Kimchi
  • Sour Pickles
  • Olives
  • Capers
  • Dilly Beans
  • Water Kefir (aka Tibicos)
  • Kombucha
  • Yogurt
  • Milk Kefir
  • Almond Milk Kefir
  • Creme Fraiche
  • Buttermilk
  • Farmstead cheese
  • Miso
  • Tempeh
  • Fish Sauce
  • Soy Sauce
  • Fermented Black Bean

*Sour pickles are different from regular pickles. Regular pickles are made by adding vinegar to the vegetable, also known as pickling. This process does not allow helpful bacteria to grow so eating ‘regular’ pickles, is not helpful in restoring balance to your gut bacteria.

Sour pickles are made by way of fermenting the vegetable in a similar manner to the sauerkraut making process. Almost any vegetable can be made into a sour pickle including cucumbers, carrots, green beans, okra, cauliflower, radishes, peppers, etc.

1 Goto, Yoshiyuki, and Hiroshi Kiyono. “Epithelial Barrier: an Interface for the Cross‐Communication between Gut Flora and Immune System.” Wiley Online Library, John Wiley & Sons, Ltd, 15 Dec. 2011, 2 Veiga, Patrick, et al. “Changes of the Human Gut Microbiome Induced by a Fermented Milk Product.” Nature News, Nature Publishing Group, 11 Sept. 2014, 3 Derrien, Muriel, and Johan E.T. van Hylckama Vlieg. “Fate, Activity, and Impact of Ingested Bacteria within the Human Gut Microbiota.” Trends in Microbiology, Elsevier Current Trends, 1 Apr. 2015, 4 Oozeer, Raish, et al. “Survival of Lactobacillus Casei in the Human Digestive Tract after Consumption of Fermented Milk.” Applied and Environmental Microbiology, American Society for Microbiology, 1 Aug. 2006,

El-Ghaish, Shady, et al. “Potential Use of Lactic Acid Bacteria for Reduction of Allergenicity and for Longer Conservation of Fermented Foods.” Trends in Food Science & Technology, Elsevier, 14 May 2011, Shi, Jing, et al. “Effects of Fermentation by Lactobacillus Casei on the Antigenicity and Allergenicity of Four Bovine Milk Proteins.” International Dairy Journal, Elsevier, 5 Nov. 2013,

If you have any questions or concerns, please call the clinic.