Diversify Your Microbiome With Fermented Vegetables

sauerkrautFermented vegetables could change your life. Sauerkraut, kimchi, and other similar food products contain many different types of bacteria, including the probiotics Lactobacillus plantarum and Lactobacillus brevis. Many, if not most, of the microscopic organisms found in fermented vegetables are not able to live and grow in the human gut; hence, they pass through you without setting up shop in your intestine. However, some may do well in the human colonic environment and could take up permanent residence in your gut, thereby contributing to boosting the diversity of your microbiome.

Boosting the diversity of your inner ecosystem

To date, no studies have specifically looked at how fermented vegetables affect the microbiota (This may change in a not so distant future though, because I’m planning to conduct a RCT on fermented vegetables and gut health later this year). That said, there’s a lot of indirect evidence to suggest that fermented vegetables are helpful for repairing a damaged gut microbiota.

First of all, studies have shown that fermented vegetables such as kimchi may promote fat loss, reduce cholesterol, favorably affect mood and mental health, and improve metabolic parameters, among other things (1, 2, 3, 4). Second, fermented vegetables such as sauerkraut contain a broad range of microorganisms, including Leuconostoc mesenteroides, Leuconostoc citreum, Leuconostoc argentinum, Lactobacillus paraplantarum, and Lactobacillus coryniformis, that are able to live in a low pH, anaerobic environment (5). Both scientific studies and anecdotal reports suggest that many of these bugs positively impact human health (1, 6, 7). Some may colonize the gut and/or transfer genetic material to microbes that are already present in the intestine.

In today’s post I’m not going to take an in-depth look at the potential health benefits of fermented vegetables. This is something I’ve done in the past. Rather, I wanted to share a couple of tips on how you can use fermented vegetables for improving the diversity and resilience of your inner ecosystem.

Over the years, I’ve read a lot of review papers, studies, and other articles on the human microbiome, gut health, probiotics, inflammation-driven diseases, and so forth. I’ve also been doing some self-experimentation with various fermented foods and supplements, and tried different dietary approaches with the clients I’ve coached over the years. The tips you’ll find in this article are based on the knowledge I’ve acquired during this time period.

Before we jump in, I want to make it clear that fermented vegetables don’t contain the broad range of microbes that are needed to repair a severely damaged gut microbiota. If your microbiota is very damaged and degraded, you may want to consider doing one or more microbiota transplants and/or taking acid-resistant “microbiota pills”.

How to use fermented vegetables to repair and diversify the microbiome

– Source

Preferably make your own fermented vegetables at home. If you can’t or won’t make your own, but rather wish to buy fermented vegetables at the store, then seek out products produced by a manufacturer that makes sauerkraut, kimchi, etc. the traditional way. Many, if not most, of the fermented vegetables you’ll find at the grocery store are either pasteurized or made from starter cultures. Do not buy these products!

– Equipment

It’s possible to make fermented vegetables in a simple glass jar without any air-lock or tight lid – you just have to make sure the vegetables stay under the brine all the time and that the batch doesn’t get moldy. It’s much easier to use a fermentation crock or another anaerobic container though. If you are going to make fermented vegetables on a regular basis, then you should strongly consider buying one or more crocks. Choose a type that has a water seal and comes with stone weights that can be used to weigh the vegetables down.

– Salt

Salt keeps pathogens at bay; however, it also inhibits the growth of some “good” bacteria. High salt concentrations are associated with decreased microbial diversity. If you use a lot of salt when you make fermented vegetables, you’re selecting for the growth of bacteria that are able to grow in a salt-heavy environment.

If you make fermented vegetables in an open jar, you may find that you need to add quite a bit of salt to keep pathogens from growing on the surface of the brine. However, if you make fermented vegetables in a container that is free of oxygen, you probably won’t have any problems with mold or other nasty bugs regardless of how much salt you use. My tip is to take it easy on the salt. Use slightly less than what most recipes recommend.

– Fermentation time

The microbiota of fermented vegetables changes throughout the fermentation period. Different bacteria dominate at different stages of the fermentation process. From the perspective of boosting the diversity of the gut microbiota, it may be better to take out and eat some fermented vegetables at several different times during the fermentation process, rather than taking out and storing everything at once.

How long you should let vegetables ferment depends on several factors, including the temperature of the room where the fermentation process occurs, the amount of salt you use, and your taste preferences. The longer you let the vegetables ferment, the more acidic they get. Vegetables can ferment for a long time without going bad. Just make sure you don’t let them ferment so long that there’s no nutrients left for the bacteria.

– Diversity

Diversity is key. If you can, make many different batches with different types of vegetables. There is a lot of overlap in regards to the types of bacteria that are present in each individual container of fermented vegetables. That said, the microbial make-ups are not identical. Each jar houses a unique microbiota. By eating a diversity of different types, rather than just one or two, you’ll expose yourself to a greater diversity of bacteria, thereby increasing the likelihood that you pick up several microbes that colonize your gut.

– Quantity and frequency

You don’t need to eat huge amounts of fermented vegetables to bring some good bugs into your gut. Actually, it’s probably detrimental to health to do so. Daily consumption of large quantities of fermented foods is an evolutionarily novel behavior that may destabilize the microbiota and inhibit the development of a healthy, diverse microbial ecosystem in the gut (6, 7). These effects may be attributed to the production of bacteriocins – toxins that could kill or inhibit the growth of microbes that are present in the human gut – by probiotic lactic acid bacteria.

Bombarding the gut with probiotics may not be as bad as bombarding it with antibiotics, but it’s certainly not advisable. Fermented vegetables are packed with bacteria – you don’t need to eat a lot of them to get some good bugs into your gut. It’s probably much better to eat small quantities of fermented foods occasionally, rather than large quantities daily. Keep in mind, the goal is not to get as many probiotics into the gut as possible, but rather to diversify the microbiota and build a stable, resilient microbial ecosystem.

Okay, that’s it. I hope you found the tips useful. As you can see, the process of using fermented vegetables to diversify the microbiome is not as simple as just eating some store-bought sauerkraut every now and then. If you try the approach described in today’s post, then please share your experience and results in the comment section.

Picture: Creative commons picture by jules. Some rights reserved


  1. Thanks for the primer on fermentation, Eirik. I have an excellent in-depth how-to book for anyone who is interested in learning more. It’s called “Fermented Vegetables” by Kristin and Christopher Shockey. It contains recipes and tips for fermenting everything imaginable. I think Amazon carries it.

    • Awesome. I’ve heard good things about that book.

      I wanted to include some book recommendations in the article, as I think a lot of people may find it easier to get started with making fermented vegetables if they have a book that tells them exactly what to do. But since I haven’t read any english books on fermentation myself, I didn’t really have anything to recommend. A good friend of mine does fermentation workshops and makes brochures containing recipes for fermented vegetables, but they are not in english.


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