What Is Fermentation? Benefits, Foods and How to Ferment - Dr. Axe

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What Is Fermentation? Benefits + How to Ferment Foods


What Is Fermentation? - Dr. Axe

You’ve heard all about the benefits of fermented foods, but just what is fermentation — and why is it so important?

Fermentation is a process used to produce the finest wine; many of our basic staples, such as bread and cheese; and pleasurable delights, including beer, chocolate, coffee and yogurt. Most importantly, though, it helps bring out tremendous benefits in many of the healthy foods you already love.

Fermentation is an easy process, enjoyed and done by anyone and anywhere with the most basic tools. Cultures around the world have been fermenting longer than we’ve been cultivating soil or writing books, benefiting from the countless delicacies as a result.

Best of all, fermentation brings out some amazing health benefits in the foods we eat.

What is fermentation good for? Well, fermentation helps increase digestion and bioavailability of nutrients, as well manage and prevent disease, including H. pylori infection, cancer, liver disease, arthritis, inflammatory bowel disease and lactose intolerance.


Furthermore, it’s been shown that fermented foods can reduce social anxiety. That’s not all.

What Is Fermentation?

What is fermentation? It’s the process of using microorganisms, such as bacteria or yeast, to convert carbohydrates to alcohol or organic acids under anaerobic conditions.

There are two types of fermentation: alcoholic and lactic acid. Alcoholic fermentation, or ethanol fermentation, is where pyruvate (from glucose metabolism) is broken down into carbon dioxide and ethanol by bacteria and yeast. Alcohol fermentation has been used to produce beer, bread and wine.

Pyruvate molecules from glucose glycolysis may be further fermented into lactic acid. Lactic acid fermentation converts lactose into lactic acid.

There are several benefits to fermenting food. First, fermentation serves to enhance the digestion of food.

Your body needs adequate digestive enzymes to properly absorb, digest and utilize nutrients in food. When vegetables like cabbage and cucumbers are left to steep and sit until the sugars are broken down to promote the growth of bacteria, this is when the vegetables are fermented.

Fermented foods are also filled with beneficial bacteria that work as reinforcement for the good bacteria in the digestive system. Since 70 percent to 80 percent of the immune system lies in the gut, having proper balance of gut flora is important.

What else is fermentation good for? It preserves food.

How? During fermentation, organisms produce acetic acid, alcohol and lactic acid, which are all “bio-preservatives” that retain nutrients and prevent spoilage. Lactic acid acts as a preservative by reducing pH, which inhibits the growth of harmful bacteria.

Many people throughout history have recognized that fermentation as a mysterious life force. Louis Pasteur, a French chemist who turned his attention to fermentation processes, worked with Lillie industrialist, a beetroot alcohol manufacturer whose factory was experiencing inconsistent results.

According to “Wild Fermentation: The Flavor, Nutrition, and Craft of Live Culture Foods”:

Pasteur’s methodical study of beetroot fermentation quickly convinced him that fermentation was a biological process. The “Mémoire sur la fermentation appelée lactique,” a study on fermentation, was published in April 1857. Pasteur solved the beetroot alcohol manufacturer’s problem by heating the beet juice to destroy naturally occurring lactic acid-producing bacteria and adding it with alcohol-producing yeast.

This was the earliest application of the heating process now credited on every milk carton, pasteurization. Pasteur’s discoveries gave a great boost to the mass production of fermented drinks and foods. These products had been enjoyed for thousands of years, created by using processes learned from nature, often accompanied by prayers, rituals and offerings.

Fish, fruits, meat, milk and vegetables are highly perishable, and our ancestors utilized every technique to store foods for later consumption. The 18th century English explorer, Captain James Cook, was recognized by the Royal Society for having conquered scurvy among his crew by sailing with large quantities of sauerkraut. His 60 barrels of kraut lasted for 27 months, and not a single crew member had scurvy, which previously killed large numbers of the crew member on a long sea voyage.

Fermentation and Probiotics

In the late 19th century, microbiologists realized microorganisms in the gastrointestinal tract of healthy individuals were different than those who were sick. These beneficial microflora were named probiotics, literally meaning “for life.”


Probiotics are microorganisms proven to exert health-promoting influences in humans and animals. The reason why fermented foods and drinks are beneficial is because of the natural probiotics they contain.

According to the Journal of Applied Microbology, the benefits of consuming probiotics include “(i) improving intestinal tract health; (ii) enhancing the immune system, synthesizing and enhancing the bioavailability of nutrients; (iii) reducing symptoms of lactose intolerance, decreasing the prevalence of allergy in susceptible individuals; and (iv) reducing risk of certain cancers.”

Probiotic bacteria not only balance the good bacteria in the gut, but they also help “tune up” the immune system. As high as 70 percent of the immune system lies in the intestine, so nurturing the bowel immunity with probiotic bacteria keeps the intestinal tract healthy.

Probiotic-rich foods include fermented cheese, kimchi and sauerkraut. Just as there are fermented foods, you can nurture your intestines with fermented probiotic beverages like kefir and kombucha.

Health Benefits

1. Improves Digestion

Fermentation breaks down nutrients into more easily digestible forms. When lactobacilli in fermented foods proliferate, their vitamin levels increase and digestibility is enhanced. They also improve the microbiome, which has a host of health benefits for digestion and more.

When it comes to soybeans, this protein-rich bean is indigestible without fermentation. Fermentation breaks down the soybeans’ complex protein into readily digestible amino acids, giving us traditional Asian ingredients, such as miso, tamari (soy sauce) and tempeh.

Milk is also difficult for many individuals to digest. A type of bacteria present in fermented dairy products converts lactose, the milk sugar that many individuals cannot tolerate, into digestible lactic acid.

In a study out of France on women who reported minor digestive problems, those women reported improved gastrointestinal digestive symptoms when fermented milk containing Bifidobacterium lactis was consumed.

2. Can Suppress H. pylori

Helicobacter pylori (H. pylori) infection is an important risk factor for many gastrointestinal diseases. Some fermented foods serve useful for suppressing H. pylori infection.

An observational study published in World Journal of Gastroenterology involving 464 participants found lower prevalence of H. pylori seropositivity in those who consumed yogurt more than once a week compared to those who did not. This confirms other research findings that fermented milk improves gastrointestinal symptoms in patients who tested positive for H. pylori.

3. Provides Anticancer Effects

Cancer is caused by activation or mutation of abnormal genes that control cell growth and division. Researchers believe probiotic cultures and fermented foods might decrease the exposure to chemical carcinogens by:

  • detoxifying the ingestion of carcinogens
  • altering the environment of the intestine and decreasing metabolic activities or populations of bacteria that may generate carcinogenic compounds
  • producing metabolic products that cause programmed cell death or apoptosis
  • producing compounds that inhibit the growth of tumor cells
  • stimulating the immune system to defend itself against cancer cell proliferation

There are several reports on the ways fermented foods can help fight cancer:

  • Large cohort studies in the Netherlands and Sweden have observed the effects of regular consumption of fermented dairy products in reducing the risk of bladder cancer.
  • Strains of bacteria called lactobacillus prevent toxicity of heavy metals by excreting harmful heavy metals and heterocyclic aromatic amines, carcinogens found in overcooking meat.
  • Kimchi, a fermented cabbage cuisine, contains strains that promote the degradation of organophosphorus pesticides by breaking down a cancer-causing food preservative called sodium nitrate.

4. Enhances Bioavailability of Nutrients

Fermentation helps create new nutrients, like B vitamins, folic acid, riboflavin, niacin, thiamine and biotin, and has been shown to improve the availability, digestibility and quantity of some dietary nutrients. The bioavailability of fat and protein are enhanced by bacterial enzymatic hydrolysis, and the production of lactic acid, butyric acid, free amino acids and short-chain fatty acids (SCFA) are increased by lactic acid bacteria.

When SCFAs are absorbed, they may help protect against pathological changes in the colonic mucosa. They play an important role in maintaining an appropriate pH in the colon, which is important in the expression of various of bacterial enzymes and in carcinogen and foreign compound metabolism in the gut.

5. Reduces Symptoms of Lactose Intolerance

Lactobacillus consumes lactose in milk and transforms it into lactic acid that may be easier for individuals to digest. Lactic acid in yogurt reduces symptoms of lactose intolerance in individuals who are lactase-deficient. This may be because the lactic acid bacteria in the milk causes an increase of lactase in the small intestine.

One review of the topic states:

In clinical practice, replacing milk with fermented dairy products allows for decreased diarrhea, better digestion and improvements in other symptoms of intolerance in participants with lactose intolerance in subjects with short-bowel syndrome and children with diarrhea.

Enhanced digestion of sucrose was shown in infants with sucrase deficiency as well.

6. Helps Treat Hepatic Disease

Non-alcoholic fatty liver disease is the buildup of extra fat in the liver cells not caused by alcohol. Liver disease can cause liver swelling, scarring, and even lead to cancer or liver failure.

In a double-blind, randomized, controlled clinical trial, some participants consumed 300 grams a day of fermented probiotic yogurt containing lactobacillus acidophilus and bifidobacterium lactis, while those in the control group consumed 300 grams a day of conventional yogurt for eight weeks. The group who consumed the probiotic yogurt had reductions in alanine aminotransferase, aspartate aminotransferase, total cholesterol and low-density lipoprotein cholesterol compared to the control group. The reduction in these parameters may be useful in management of liver disease risk factors.

7. May Improve Arthritis Symptoms

Most people know someone with arthritis. It is the leading cause of disability, with symptoms including aching, pain, stiffness and swelling of the joints.

It is thought that inflammation associated with rheumatoid arthritis symptoms may be modulated by the consumption of fermented foods.

A randomized, double-blind, placebo-controlled pilot study of probiotics in active rheumatoid arthritis found that “patients with at least four swollen and four tender joints and stable medications with no steroids for at least one month prior to and during the study, showed a significant improvement in the Health Assessment Questionnaire score after three months of probiotic treatment.”

In fact, many studies show gut microbiota and arthritis are connected, and probiotics as the result of fermentation have been shown to work as an adjunct therapy for arthritis.

8. Helps Treat Inflammatory Bowel Disease

Fermented milk supplemented with probiotics can exhibit a direct effect in the gut in managing inflammatory and functional bowel disorders. Clinical trials show that probiotics help reduce abdominal pain, bloating, constipation and flatulence in patients with inflammatory bowel disease, including Crohn’s disease. (14)

Top Fermented Foods

  1. Kefir
  2. Kombucha
  3. Sauerkraut
  4. Pickles
  5. Miso
  6. Tempeh
  7. Natto
  8. Kimchi
  9. Raw Cheese
  10. Yogurt
  11. Apple Cider Vinegar
  12. Kvass
  13. Sourdough Bread
  14. Cottage Cheese
  15. Coconut Kefir

How to Ferment Foods

Fermenting your own food seems like a daunting adventure, but it can be done at home with the help of easy-to-follow instructions. Fermented foods are made by a process called lacto-fermentation, which is feeding starch and sugars to natural bacteria in the food, creating lactic acid.

This process is used to create beneficial B vitamins, enzymes, omega-3 fatty acids and strains of probiotics.

Fermented food are budget-friendly and will help you to secure food for a longer period of time. Plus, fermenting is better than traditional canning methods.

Almost any fruit or vegetable can be fermented, and you can include different herbs and spices to add variety to your ferments.

Here’s a list on how to get started:

1. Equipment

The basic pieces of equipment required for most fermentation are containers to keep foods in.

Glass containers are a great option because they don’t contain chemicals like BPA and don’t scratch easily. Plastic containers should be avoided for various of reasons, such as plastic is easy to damage, leeching chemicals and foreign bacteria that can affect the fermentation.

Ceramic containers are commonly used to secure large batches of vegetables. Food-grade porcelain containers can be used to ferment, but avoid vases and decorative pottery because they are not used for fermenting food.

Cloth or coffee paper filters are used to secure the small jars with a right rubber band. A butter muslin and a tight-weave towel with a rubber band can also be used to secure the fermented food.

Canning lids should have airlocks to reduce the chances of mold and yeast formation.

2. Prepare Vegetables

Chopping, slicing, grating or shredding are several ways to prepare the vegetables for fermentation. Cutting the vegetables into smaller pieces speeds up the fermentation process.

3. Salt, Whey or Starter Culture

Depending on what you want to ferment, the recipe may call specifically for salt, starter culture, sugar or whey.

4. Weighing

It’s best to use river rocks to securely hold the vegetables under the brine. Those are available at your local river, or you can boil them for 15–20 minutes after scrubbing them with soap.

You can also use heavy parts of a vegetable to add some weight to the fermented vegetables below the brine. It is important to keep the fermented vegetables under the brine to prevent spoilage.

5. Storing

When vegetables are done fermenting, move them to a cold environment. You’ll know when you vegetables are ready for storage if you notice bubbling, a sour aroma and good taste.

If you notice a rotting or spoiled smell, discard, clean the container thoroughly and try again another time.

Safety and Precautions

Due to the possibility of contamination of improperly fermented food and raw milk, certain fermented foods should be avoided during pregnancy.

Follow recommended temperatures, time and weight usage during fermentation to prevent contamination.

Tyramine is natural substance found in aged and fermented foods. It’s a well-accepted migraine trigger, so be careful if you suffer from migraines.

Final Thoughts

  • Fermentation is everywhere and has been used by humans for thousands of years.
  • What is fermentation good for? Fermentation has many health benefits, such as enhancing bioavailability, reducing symptoms of lactose intolerance, and holding anti-inflammatory and anticancer properties.
  • Fermented foods house beneficial bacteria called probiotics that can be found in eating kimchi, kefir, natto, tempeh, kombucha, yogurt and more.
  • Proper preparation of fermented foods can allow you to enjoy and benefit from your tasty fermentation for a very long time.

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