6 Reasons to Eat Fermented Foods

Live-culture revivalist Sandor Katz explains why letting some foods go bad makes them even better—increasing both flavor and nutrition.
Wild West Ferments photo by Trinette Reed

Wild West Ferments, a business in northern California, holds workshops on fermentation. Photo by Trinette Reed.

Every day I eat food that’s teeming with bacteria—billions of them.

To some, this may sound like reckless behavior, consorting with supposedly dangerous enemies. After all, we live in the midst of a war on bacteria, which teaches us to fear bacteria as vectors of contagion and deploys an arsenal of chemical compounds to destroy all types of microorganisms. Yet eating bacterially rich food is an important part of how I stay healthy.

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For me, it started with sauerkraut. After moving to the country and taking up gardening, the fleeting abundance of cabbage in our garden inspired me to learn how to make sauerkraut, primarily as a strategy for preservation. I found an old crock buried in our barn, harvested cabbage from the garden, chopped it up, salted it, pounded it, packed it into the crock, and waited.

That first batch of kraut 20 years ago tasted so alive and powerfully nutritious! Its sharp flavor sent my salivary glands into a frenzy and got me hooked on fermentation. I have made sauerkraut ever since, earning the nickname Sandorkraut, even as my repertoire has expanded. For two decades now, I have explored and experimented widely in the realm of fermentation, investigating and immersing myself in ancient wisdom. I have learned about fermentation’s integral role in food and healing all around the world. I have come to believe that fermentation has continued and growing relevance in the 21st century, and I now consider myself a fermentation revivalist, with a mission to share fermentation skills, information, and resources.

It’s rare for anyone, almost anywhere, to go through a day without eating or drinking something fermented. Products of fermentation are some of our most basic daily staples and favorite special treats, and this has been true for longer than recorded history in almost every region of the world. Fermented foods and beverages are celebrated for their powerful, complex flavors and aromas, recognized for their unique healing qualities, revered as holy sacraments, and relied upon for preserving food from seasons of plenty for survival through leaner times.

1. Deep flavor

Walk into any gourmet emporium and look around. What you will see are products of fermentation. Cheeses are fermented. Breads are fermented. Cured meats are fermented. Coffee, chocolate, vanilla, vinegar, sauerkraut, kimchi, pickles, wine, beer, olives—all fermented. Fermentation creates strong flavors. Not all of the flavors of fermentation are beloved by everyone—think stinky cheeses. Rather they are acquired tastes, and not everyone acquires all of them. But once you learn to appreciate their complexity, ferments can fill you with desire and keep you coming back for more.

2. Probiotics

It is becoming increasingly clear that a healthy bacterial microflora is essential to health and well-being. The bacteria in our intestines exist in complex communities that help us digest food and assimilate nutrients, synthesize essential nutrients for us, and regulate our immune responses and many other aspects of our functionality. Especially given our frequent exposure to chemicals that kill bacteria, such as antibiotic drugs, antibacterial cleaning products, and chlorinated water, we can benefit from bacteria-rich foods, which stimulate immunity and seem to help replenish and diversify our gut bacteria. Beneficial bacteria are frequently marketed in capsule form, but traditional fermented foods (if they have not been cooked or heat-processed after fermentation) are full of beneficial bacteria, too. And the diversity of bacteria found in a variety of live-culture fermented foods exceeds what is found in most probiotic supplements.

3. Improved nutrient availability

Fermented foods are literally predigested by microorganisms. Minerals become more available for our bodies to absorb, and dense, compound nutrients that can be difficult for our bodies to break down are already to some extent digested before we eat them. For instance, when protein-rich soybeans are fermented, their protein is digested into amino acids, the building blocks of proteins, which are much easier for our bodies to use. Similarly, the lactose in milk, which so many of us cannot digest, is broken down by fermentation. Even gluten gets broken down in bread raised by a mixed fermentation of both yeast and bacteria (as in sourdough, but not pure yeast breads).

4. Fermented medicine

In addition to breaking down the nutrients in whatever ingredients are being fermented, the fermenting bacteria contribute their metabolic byproducts, some of which are unique compounds that have been found to have startling, beneficial qualities. For instance the isothiocyanates that are generated by bacteria in sauerkraut fermentation are regarded as anti-carcinogenic. Nattokinase, found in the Japanese soy ferment natto, is being used as a blood thinner to regulate blood clotting and to break down the fibers that can build up on the walls of blood vessels and clog them. The scientific study of these fermentation byproducts is relatively new. Further research will likely reveal more of them with beneficial healing qualities.

5. Preservation

Before canning became widespread in the 19th century and refrigeration became available in the 20th, fermentation was one of the few means available for food preservation, along with drying, heavy salting, and smoking. Fermentation remains an important mode of food preservation: Hard cheeses are preserved milk; salamis and hams are preserved meat; sauerkraut is preserved cabbage (and frequently other vegetables); wine and hard cider are preserved fruit. These and other ferments have been important for survival in many places.

6. Energy efficiency

Fermentation evolved in distinctive ways everywhere, as a way to make food more useful, generally in energy-efficient ways. Certain ferments contribute to energy efficiency by dramatically reducing cooking time. For instance, tempeh reduces the time required to cook soybeans by about 90 percent. Our ubiquitous fridges and freezers make the preservation value of fermented foods seem less critical than it once was. But uncertainty about the continued availability of cheap energy in the future might give us pause and remind us of the relevance of holding onto the food preservation wisdom developed and passed down as integral elements of cultural practices everywhere.

We have been indoctrinated to believe that bacteria are dangerous enemies. But we must recognize in bacteria not only our cellular origins and mutualistic partners, but our best hope for pathways into the future. Bacteria have been found to decompose many pollutants. As we imagine how to deal with the toxic wastes we have dumped into our land, our water, and our bodies, bacteria offer us potential solutions. Bacteria possess incredible genetic flexibility. They can exchange genes, shed genes, and incorporate genes from their environments. They are shape-shifters, constantly mutating and adapting. How can we possibly adapt without them?