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Food Fermentation: How It Works, Health Benefits, and 6 Beginner Tips

An image of a jar being filled with layers of cabbage and carrot to be fermentedFermentation describes a popular process in food processing where microbes break down carbohydrates anaerobically. Although food fermentation is hardly new in the health and wellness industries, it has become increasingly popular in recent years. Many people are now embracing the practice of fermenting their food at home.

Food fermentation is used to produce many types of common foods, like cheese, wine, yogurt, and bread. This process has a lot of health benefits for people looking to boost the levels of nutrients in their diets. This article will cover the basic things you need to know about fermentation, including its top five benefits for nutritional health.

What Is Fermentation?

Fermentation is a metabolic process involving microorganisms that cause specific changes to certain foods or beverages without oxygen. The processed foods typically have a high glucose content — the primary molecule the microorganisms feed on. As the microorganisms feed on the sugar content of the starting substrate, they release other substances such as carbon dioxide, acids, alcohol, and energy.

They work without oxygen to extract energy from processed food or beverages. The most common fermentation microorganism that you may have heard of is yeast. Others include bacteria and molds, while some even carry out fermentation in the presence of oxygen.

How Does Fermentation Work?

There are many types of fermentation, all categorized by the end products of the process. Three of the most commonly employed types of fermentation for food and beverages are:

  1. Ethanol Fermentation: This process is used to produce alcoholic beverages where yeast converts sugar in the starting substance to alcohol and carbon dioxide.
  2. Lactic Acid Fermentation: This fermentation commonly improves the flavor or longevity of dairy and vegetable products. You can also find this type of fermentation within the body - muscles undergo lactic acid fermentation during intense muscle activity.
  3. Acetic Acid Fermentation: This process converts starches and sugars from grains and fruits into sour condiments and vinegar. Examples of products from this type of fermentation are kombucha, apple cider vinegar, and wine vinegar.

Daily Food Applications of Fermentation

Alcoholic drinks, such as wine from fruit juice and beer from grains, are commonly produced by fermentation. Because of their high starch content, potatoes may be fermented and distilled to produce gin and vodka.

Making bread also requires fermentation. When yeast, flour, water, and sugar are mixed to make the dough, the yeast metabolizes the sugar and releases carbon dioxide, which gives the bread its rising effect. Lactobacilli and yeast are both used in particular types of bread, like sourdough. The mixture of lactobacilli and yeast is primarily responsible for the dough's flexibility and characteristic sour flavor.

Lactic acid fermentation preserves or gives vegetables and dairy products like yogurt, sauerkraut, pickles, and kimchi improved flavor and texture.

Stages of Fermentation

Fermentation has different stages depending on what starting substrate you’re fermenting and what your intended end product is. The basic steps are:

1. Primary Fermentation

Although this phase is relatively brief, it is a crucial step in starting the process. Here, the microbes present for fermentation begin rapidly breaking down the starting substrates. These could be raw ingredients like vegetables, fruit, or dairy. There is typically a surrounding liquid (e.g., brine for vegetable fermentation) that contains the microbes. These microbes prevent putrefying bacteria from attacking the food substrate instead.

While they protect the integrity of the substrate, yeast or other types of microbes also convert the carbohydrates in the substrate to other substances like acids and alcohols.

2. Secondary Fermentation

An image of a man looking at a glass of beerThe secondary stage of fermentation lasts much longer than the primary stage. Here, the alcohol levels rise as the microbes in the primary stage die off because of a reduction in their food source: carbohydrates. This secondary stage may last for several days or weeks, allowing the alcohol levels to rise steadily.

At this stage, the pH of the ferment has drastically changed from when the process first began, altering the reactions between the microbes, the food substrate, and the environment.

Depending on what you’re making, the right time to end the fermentation process will vary.

For example, to create unique products, beer and wine will still undergo several fermentation stages. To make alcoholic beverages, you typically stop the fermentation when the alcohol percentage reaches 12-15%. After, you distill to eliminate the water and condense the alcohol to a higher alcohol percentage.

Advantages of Fermentation

Fermented foods are characteristically rich in probiotics that contribute significantly to gut health. Probiotics are helpful microorganisms that help the gut efficiently extract the proper nutrients from food. There are multiple health benefits of food fermentation:

  • Probiotics, enzymes, and lactic acid facilitate the intake of vitamins.
  • Fermentation increases the efficacy of vitamin B and vitamin C in the body.
  • Fermentation helps the gut to neutralize anti-nutrients that may be in specific foods like nuts, seeds, legumes, etc. These anti-nutrients like phytic acids and lectins make starches, proteins, and fats harder to digest.
  • Fermentation enhances riboflavin, niacin, thiamin, and biotin, all B vitamins, thus making them more accessible for easy absorption.
  • The probiotics in fermented foods help to maintain a healthy gut by producing antibiotic, antifungal, and antiviral agents. They also provide a suitably acidic environment, making it hard for harmful microorganisms or pathogens to thrive in the gut.
  • Fermented foods improve digestion and also promote bowel regularity. This is especially great for people who struggle with constipation, poor stool consistency, and frequency.
  • Fermentation can be helpful for people who are lactose intolerant - it breaks down the lactose in milk to simpler sugars (glucose and galactose) so that certain products like yogurt, cheese, and kefir are less difficult to digest.
  • The probiotics in fermented foods contribute to improving heart and cardiovascular health.
  • Fermented foods may help improve mood. Poor gut health contributes to chronic inflammatory responses associated with mood instability. Via the gut-brain axis, fermented foods can help regulate the central nervous system.
  • Some research has linked fermented foods to improved brain function and mental health. Studies show that probiotics contribute to easing symptoms of anxiety and depression. They also help to improve cognitive function and reduce problems like brain fog.
  • Consuming fermented foods can help you achieve any weight loss goals you may have. Some research has also linked some strains of probiotics to weight loss and decreased belly fat.
  • A happy gut means happy skin! Fermented foods help to keep the skin healthy by reducing systemic inflammation and excessive sebum production.

How Fermented Foods Help Reduce Inflammation

The bacteria in your gut are a prominent part of your immune system and Inflammation Circuit. By outcompeting harmful bacteria and improving the digestability of foods, the healthy bacteria in fermented foods can reduce inflammation in your gut. This in turn lowers the activation of your immune system, reducing systemic inflammation as well, and making your immune system better prepared to fight threats when they do occur.

An image of friendly bacteriaWith a high level of friendly bacteria in your gut, fermented foods give your immune system a much-needed boost and reduce your risk of falling ill. That also means that they help you recover faster and more efficiently in the event of any sickness.

The Inflammation circuit describes one of the six circuits of the NeuroEndoMetabolic (NEM) Stress Response System. The NEM is the body’s normal way of responding to stress. In this system, the Inflammatory circuit is composed of the gastrointestinal tract (digestive system), microbiome, and immune system.

This circuit is responsible for the body's response to stress for foreign agents present in the body. If you are stressed, your gut will find a way to give you signs. One sign of chronic stress is Adrenal Fatigue Syndrome, which includes many symptoms such as inflammation and gut problems. With the benefits of fermented foods for the gut, these foods can help enhance the health of your NEM system. This makes the incorporation of fermented foods into your diet an essential part of NEM Nutritional Therapy.

Disadvantages of Fermentation

Fermented foods are‌ safe for most people. Some people (typically individuals with a histamine tolerance) may experience negative effects. Some disadvantages of fermentation are:

  • The high probiotic content may cause initial and temporary gas and bloating in some people. This may be more pronounced or prolonged with high-fiber fermented foods like sauerkraut and kimchi.
  • Foods fermented at home may contain unexpected bacteria strains and may disagree with the gut when consumed. When fermenting your own foods at home, it's important to follow proper hygiene guidelines as closely as you can.
  • People who are pregnant, immunocompromised, allergic, or have histamine sensitivity should not eat fermented foods.

Common Fermented Foods

There are many everyday fermented foods consumed across the world, and many of them are easily accessible. Some of the most common fermented foods include:

  • Cheese
  • Wine
  • Yogurt
  • Beer
  • Sourdough bread
  • Tempeh
  • Pickles
  • Bread
  • Natto
  • Kombucha
  • Vinegar
  • Apple cider vinegar
  • Sauerkraut
  • Kimchi
  • Salami
  • Olives
  • Miso
  • Kefir

Healthy Fermented Foods That Contain Probiotics

However, do note that not all of these foods contain the live and active probiotics that bring the most health benefits. Probiotic foods include:

  • Yogurt
  • Kefir
  • Kombucha
  • Natto
  • Miso
  • Tempeh
  • Kimchi
  • Sauerkraut

Six Tips for Starting Food Fermentation

1. Start Small

Fermentation is a craft that has been perfected over centuries. Start small and graduate onto bigger projects. For example, salted vegetables are a great beginner project to try your hand at. Try this with crunchy vegetables like onions, carrots, and cabbages, before moving on to more challenging fermentation projects.

2. Keep The Air Out

Allowing your ferment to come in contact with air may disrupt the fermentation process. Submerging your food in brine (a salt solution) can help keep air away and you can store your food in tight-lidded containers. You can also control the pH of the fermentation by using vinegar in your brine as well. Controlling pH will help determine how much oxygen will be present.

3. Storage

An image of mason jars full of fermented foodsMany people who ferment food at home use mason jars with tight lids or other similar containers. Typically, whatever container you use should have a valve or release to let out the carbon dioxide produced during fermentation. Sometimes fermentation is done using only a cloth over the ferment, which is later replaced with an airtight seal once fermentation is complete.

For a more hands-on approach, you might alternate between opening and shutting your sealed containers to release the carbon dioxide manually. You may not need this if your end product relies on carbonation, such as wine or kombucha.

4. Keep The Room Warm

Most fermentation microbes do well in warm, room-temperature environments. While the exact temperature will vary from microbe to microbe, drastic temperature changes while fermenting can significantly disrupt the process. Colder temperatures will slow down the fermentation process and sometimes, may even stop it entirely. Under extreme heat, you may end up killing off the essential microbes for the fermentation process.

5. Keep Your Equipment Clean

The key to fermentation is employing good bacteria to work on your food substrate. With dirty equipment, you are letting harmful bacteria interact with your ferment, and that spells bad news for your end results. Ensure that your hands, tools, workspace, and containers are clean before you use them. Avoid double-dipping when stirring or tasting to prevent introducing unwanted bacteria.

6. If It Looks or Smells Funky, Something’s Off

Fermented products are not supposed to smell or look bad. Instead, it should have a light, tangy smell. If it stinks and has a white or creamy film, then you may have a contaminated batch. A slimy texture, pink hue, or dried-out look may also be telltale signs that something went wrong in the fermentation process.


Fermentation uses yeast and bacteria to break down carbohydrates in starting food substrates, typically in the absence of oxygen. It is an amazing natural tool that can help provide essential probiotics, nutrients, and improve so many processes in the body. The benefits of fermentation for gut health include improved nutrient absorption, enhanced immunity, and prevention of pathogenic activity within the gut. Fermentation also enhances the taste of foods, contributing to a delicious and healthy diet. Plus, there are many ways to incorporate fermentation into your diet to enjoy all its benefits.

If you have questions about the best ways to add probiotics and fermented foods into your diet, we can help. Call us at +1 (626) 571-1234 for a free initial consultation to talk to one of our expert coaches, or use our Ask the Doctor system by clicking here.

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Dr. Lam’s Key Question

Food fermentation plays a significant role in improving the performance of your gut. Consuming fermented foods also boost immunity, brain function, healthy weight, and mood regulation. Recently, fermented foods have been linked to improving mental health.