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March 13, 2019

The Facts on Fermented Foods

Written by Avance Care registered dietitian Julia Bumpus, MS, RDN, LDN


Fermented foods are foods that have undergone the process of fermentation, where carbohydrates are converted to alcohol or organic acids using microorganisms (yeasts or bacteria) without oxygen present.  This just means that fermentation can create alcohol or help to preserve the food. Preservation prevents spoilage and the growth of harmful microorganisms.

Fermenting food is a long-standing tradition. As far back as a hundred years ago, renowned scientist Elie Metchnikoff studied them and theorized that yogurt containing friendly bacteria could enhance health and delay aging by feeding the healthy bacteria in the intestines.1 Fermented foods and beverages have many benefits due to the longer shelf life & health promoting properties.2 

Certain fermented foods provide a dietary source of live microorganisms that are not harmful and actually improve our health.2 These are what we call “probiotics.” Most foods that contain the actual probiotic organisms will have this identified on the label.  Some foods were fermented by the organisms but no longer contain the live strains.  Either way, fermented foods can be a healthy way to add some variety to your diet!

Live probiotics in these foods produce substances that inhibit bad, disease-causing bacteria in our digestive system. These probiotics or, good bacteria, compete for nutrients with the bad bacteria.  This helps decrease the bad bacteria and increase the population of good bacteria which improves gut health and reduces risk of unpleasant digestive symptoms (diarrhea, constipation, gas and bloating).  Research has also found that these friendly probiotics can help to stimulate the body’s immune system.3   Moreover, the bacteria in these foods can synthesize vitamins, minerals and produce biologically active peptides. These peptides have health benefits such as helping to lower blood pressure. They may also have anti-cancer and anti-oxidant properties.4

Fermented dairy products may have an advantage of being easier to digest than non-fermented dairy. This is because the friendly bacteria begin breaking down lactose during the fermentation and continue to help break down lactose during digestion.3  This is beneficial for those suffering from many of the unpleasant symptoms of lactose intolerance.


Foods that introduce probiotics into the diet:

  • Yogurt: Yogurt is a commonly consumed fermented food made by lactic acid bacteria.  These bacteria ferment the lactose into lactic acid, which is why it can taste tangy or tart.  To get the benefit of the healthy bacteria, be sure to choose yogurts containing the actual probiotic strains. Examples include: Activia or Yoplait Yo Plus.
  • Kefir: Kefir is a fermented milk drink with a sour or tangy taste. It’s different from yogurt in that it is fermented with both bacteria and yeast and is liquid in form. Kefir can be consumed as is, incorporated into a smoothie or even turned into an ice-cream treat. It can also be used a base for a dip, salad dressing or soup.  Kefir can even be substituted for yogurt or buttermilk in your favorite baked goods like banana bread or waffles.5
  • Kombucha: Kombucha is black, green or oolong tea that is sweetened and fermented by a colony of both bacteria and yeast. The fermentation of the tea by both these microorganisms creates a floating layer on the surface of the fermented tea.6 Kombucha is typically consumed cold and can be bought in the bottle at many grocery stores in a variety of unique flavors.


Ideas to add other fermented foods in the diet: These foods are fermented from friendly microorganisms however they do not contain the actual live bacteria.

  • Sauerkraut: Sauerkraut is made from green cabbage that is usually shredded and fermented by the lactobacillus bacteria. The process of heating and pasteurizing kills the live micro-organisms, so canned sauerkraut will not contain the live bacteria; however, the fresh sauerkraut in the cold section does contain living cultures. We all know it tastes good on a hot dog, but this topping adds another dimension of flavor to many other foods! Cut an avocado in half and fill with sauerkraut or add it to crackers and cheese.  Try sauerkraut in a green salad or smoothie, or boost the flavor on a sandwich or scrambled eggs.7
  • Miso: Miso comes in the form of paste and is made from fermented soy beans. Many different varieties exist depending on what other ingredients are added. It has traditionally been used as a seasoning for soups, spreads and sauces in Japanese cooking. Most people might recognize miso as a type of soup, but it can season many different kinds of foods. It can be used to glaze vegetables or marinate or flavor meat. It can also be added to ordinary condiments such as mustard, mayo, dips and dressings for a unique twist.8 
  • Kimchi: Kimchi is a traditional Korean side dish comprised of salted and fermented Napa cabbage & radishes. It is prepared with a variety of seasonings like scallions, garlic and ginger. Use kimchi to add flavor to a traditional grilled cheese sandwich, burger or taco.  Use it as a topping for items like baked potatoes or deviled eggs or sauté with it with greens such as kale, swiss chard or brussels sprouts.
  • Sourdough Bread: Believe it or not, this bread is actually a fermented food! Sourdough bread is made by fermenting flour and water by lactobacillus bacteria and yeast. It does have a sour taste but can still be enjoyed a variety of different ways.  Use sourdough for a grilled cheese sandwich or as the bread for French toast. It can serve as the base for bruschetta or made into croutons if the bread has gone stale. 9
  • Tempeh: Tempeh is a vegetarian protein source made through fermentation of whole soy beans. 10 It is pressed into a cake and has a firm and chewy texture with a slightly nutty taste. 10 Like non-vegetarian protein sources, tempeh can be steamed, sautéed, baked or marinated to add more flavor.10 Although it does not contain the live bacteria due to pasteurization, it is very nutritious, containing adequate amounts of protein, iron and calcium.11  Tempeh is a great substitution for meat. Try sautéing it in a stir fry or crumbling into vegetarian tacos or spaghetti sauce!


  1. Recycling Metchnikoff: Probiotics, the Intestinal Microbiome and the Quest for Long Life. Front Public Health. 2013; 1:52.
  2. Health benefits of fermented foods. Microbiota and beyond. Current opinion in biotechnology. Volume 44. April 2017. 94-104.
  3. Inclusion of Fermented Foods in Food Guides Around the World. Nutrients. 2015 Jan; 7(1): 390–404.
  4. Health Impacts of Fermented Foods. Crit Rev Food Sci Nutr.2017 Sep 25:1-22
  6. Kombucha: a systematic review of the empirical evidence of human health benefit. Ann Epidemiol.2018 Nov 10. pii: S1047-2797(18)30738-5

Julia is the RD at the Durham and Morrisville Avance Care locations. She enjoys anything outside such as reading, running or walking the dogs. She also loves to cook new recipes, paint or do home projects like redoing furniture. She makes many weekend visits around NC to hang out with family and friends. She has 2 dogs and loves hanging with her niece and nephew (the cutie in the picture).

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