What is fermentation and are fermented foods beneficial for me?

What is fermentation and are fermented foods beneficial for me?

By Desiree Nielsen, Registered Dietitian

Fermented foods are now firmly entrenched in the wellness world. If you’re into nutrition – or gut health – you’ve probably already heard of fermented foods like kombucha, kefir or yogurt. But, what is fermentation exactly? And, are fermented foods good for you? Here’s what you need to know, from a registered dietitian, along with a list of the top ten fermented foods.

What is fermentation?

Fermentation is the metabolic process where microbes( yeast or bacteria) transform carbohydrates into end products like acids, alcohol, or gases. This happens without the presence of oxygen – we say fermentation is anaerobic. Fermentation can occur anywhere in nature (think ripe fruit rotting if it isn’t picked) and it can happen in our bodies too. Our gut microbiome ferments the fibres that we consume to produce helpful short chain fatty acids such as acetate, lactate and butyrate as well as intestinal gasses.

While fermentation is the overall process, there are actually different kinds of fermentation, depending on what is doing the fermenting. In fermented foods, there are three different types that commonly pop up: alcoholic, lactic acid, and acetic acid fermentation.

  • Alcoholic fermentation: fermentation by yeasts, and some bacteria, that produce alcohol from naturally occurring carbohydrates in foods, like barley in the production of beer.
  • Lactic acid fermentation: fermentation by lactic acid-producing bacteria (LAB) that create lactic acid from naturally occurring sugars in foods, such as the lactose in dairy products to make yogurt.
  • Acetic acid fermentation: acetic acid production is actually a two-step process. The first step is the creation of alcohol by yeasts. And the second step is fermentation of the alcohol by acetic acid-producing bacteria, such as the creation of apple cider vinegar.

 Furthermore, the fermentation process is not only beneficial for food preservation, but fermented food also helps increase the beneficial bacteria and probiotics in the gut.

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Top 10 Fermented Foods (List)

Many of our most beloved food and drink are fermented, such as wine, beer, cheese and even chocolate! However, not all fermented foods contain live-active microbes. Microbes can die off in the fermentation process when all the available food has been fermented, as is common with yogurt bacteria. They can also be killed off by cooking or pasteurization. But when we talk about fermented foods, we usually think of the foods that contain living beneficial bacteria and microbes, such as the foods in this fermented foods list below! And you might not know this, but Bio-K+ fresh drinkable probiotics are fermented! So Bio-K+ is unique in that it is a living, fermented food made from 100% probiotic, lactic acid bacteria.

  • Apple Cider Vinegar: yeasts transform the sugar in apples into alcohol, which is fermented by acetic acid bacteria to produce the acetic acid that gives apple cider vinegar its tang.
  • Kefir: the fermentation starter for kefir is called a “grain”. These “grains” are actually a mixture of bacteria (lactic acid and acetic acid) as well as yeasts to create a slightly sparkling, tart drink. You can find kefir made from dairy, coconut or even a water base.
  • Kimchi: the word kimchi describes a style of spicy, lacto-fermented vegetables that is traditional to Korean cuisine. Kimchi can be made from many different vegetables, mixed with a paste of gojuchang chili paste, plenty of garlic and salt.
  • Kombucha: kombucha is started with a SCOBY: a symbiotic culture of bacteria (acetic and lactic acid) and yeasts. Tea and sugar are the base for the fermentation and the result is a fizzy beverage with just a hint of vinegar-like tang.
  • Miso: miso is a salty, umami-rich fermented soybean paste traditional to Japanese cuisine. Miso is fermented in a two-step process: Aspergillus oryzae mold is used to create the koji starter, then the koji is added to a soybean paste with salt, and left to ferment with yeast and bacteria.
  • Natto: A fermented whole soybean dish common in Japanese cuisine. It has a unique stringy texture that forms after aging a bacterial ferment of cooked soybeans.
  • Lacto-fermented Pickles: many vegetables can be fermented with lactic-acid-producing bacteria found both on the vegetables and in our air, either by salting high water vegetables like cabbage or by creating a brine for lower water vegetables like beets. Salt is critical to lacto-fermentation as it blocks the growth of more harmful microbes while the lactic acid bacteria develop.
  • Sauerkraut: sauerkraut is a lacto-fermented cabbage pickle common in European cuisines. Cabbage is salted and then pressed to release its brine and left to ferment with lactic acid bacteria to produce a salty, tangy vegetable pickle.
  • Tempeh: tempeh is a fermented soybean block, originating in Indonesia, that is fermented in two steps. First, soybeans are fermented with bacteria; then, the fermented soybeans are inoculated with a mold, Rhizopus oligosporus, and fermented into a “cake” or block. This one is a bit of a wild card as it needs to be cooked, which will kill off any live microbes present in the food.
  • Yogurt: yogurt is probably the most common fermented food in North America and it is produced by fermenting milk or non-dairy milks with lactic acid bacteria. It’s a common misconception that yogurt is always probiotic. In fact, yogurt bacteria tend to die off the yogurt making process, so approved probiotic bacteria are added at the end of manufacturing.

Unlike other fermented foods, Bio-K+ offers research-verified strains of lactic acid producing bacteria in large enough amounts to have a specific benefit. Each little white bottle of Bio-K+ contains a guaranteed minimum of 50 Billion CFU!

Fermented Foods for Gut Health

Fermenting food has a variety of health benefits, but it's especially beneficial for a healthy gut. Fermented foods are commonly recommended for better gut health, due to the presence of friendly microbes, and the short chain fatty acids they produce. A balanced, healthy gut also means balanced gut microbes. Since fermented foods help increase the "good bacteria" in the gut, they can help balance, and even fight off the "bad bacteria". 

What’s more, fermented foods are made from nutrient-dense foods like vegetables, meaning they contain the vitamins, minerals and phytochemicals from these plants. So, you may be surprised that until recently, there weren’t many convincing studies to show us that fermented foods have a specific benefit on human health!

The exception to this lack of evidence is kimchi and kefir, as there is a small but intriguing body of research to suggest kefir may benefit gut health1 and that kimchi may be supportive of cardiometabolic health2 such as improving blood pressure.

However, one of the most intriguing studies on the health benefits of fermented foods was published just last year. A group of Stanford researchers compared 10 weeks of high fibre foods with 10 weeks of fermented foods intake3 and found that the fermented foods were able to shift the gut microbiome and decrease inflammatory markers.

Support a Healthy Gut Microbe with Bio-K+

Fermented foods are a wonderful addition to any gut-healthy diet; whenever you can, try to include more of them in your daily routine, alongside plenty of whole plant foods to help keep your gut microbiome healthy and happy. But, if you're looking for a more potent effect, consider Bio-K+ fresh, drinkable probiotic. This living ferment of 100% probiotic bacteria contains a guaranteed minimum of 50 billion live active bacteria, supported by over 20 years of clinical research!

Join our community and learn more about probiotics for gut and overall health. 



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Desiree Nielsen Registered Dietitian
About the author
Desiree Nielsen is a registered dietitian, author and host of the vvegetarian ccooking sshow, The Urban Vegetarian. Desiree takes an evidence-based, integrative approach to her dietetics work, with a focus on anti-inflammatory, plant-centredcentered nutrition and digestive health.
View all articles by Desiree Nielsen
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