Scientists have learned that the variety of microbes that live in your gut are as unique to you as your fingerprint. This population of microbial flora can be rapidly altered after exposure to foods, toxins, antibiotics and even lifestyle choices. Each microbe performs a function and must be balanced for you to maintain optimal health.
Potentially harmful microbes are only dangerous when they overwhelm beneficial ones. Essentially, this means living in a sterile environment is not ideal since the loss of your gut microbiome and the microbes living on your skin will adversely affect your health; this happens when we use antibacterial soaps and antibiotics.
Researchers understand that diseases are likely influenced by what happens in the gut microbiome. Some of the conditions identified thus far are cancer, autoimmune disorders, autism, cardiovascular disease and obesity.1,2,3 Your gut microbiome can also influence the effectiveness of certain drugs, including those prescribed for mental health.
Since your gut can undergo rapid change based on your actions, you have the ability to positively or negatively affect its health and diversity by making simple alterations to the food you eat.
Fermentation Creates Health-Promoting Components
Historically, the primary reason for fermenting was to preserve food. Over time, many cultures incorporated fermented foods into their daily diets and some were credited with a selection of foods they shared with the world. For example, Japanese natto, Korean kimchi and German sauerkraut are popular in many areas outside their respective places of origin.4
The process of fermenting food is controlled by the microorganisms involved and the type of food. Yeast produces alcohol and carbon dioxide, while lactic acid bacterium produces more lactic acid. Most fermented foods from the grocery don’t contain live cultures, which are a primary benefit of the food. Instead, before packaging, they may be smoked, baked, pasteurized or filtered.
There is a growing consensus that the fermentation process adds nutritional benefits by transforming the food and forming bioavailable end products, including an increasing density of vitamins. Some of the plant toxins may also be removed.
During the process, biologically active peptides are formed. In one paper published in Clinical Reviews in Food Science and Nutrition, the authors listed some of those peptides and their multiple health benefits:5
“Among these peptides, conjugated linoleic acids (CLA) have a blood pressure lowering effect, exopolysaccharides exhibit prebiotic properties, bacteriocins show anti-microbial effects, sphingolipids have anti-carcinogenic and anti-microbial properties, and bioactive peptides exhibit anti-oxidant, anti-microbial, opioid antagonist, anti-allergenic, and blood pressure lowering effects.
As a result, fermented foods provide many health benefits such as anti-oxidant, anti-microbial, anti-fungal, anti-inflammatory, anti-diabetic and anti-atherosclerotic activity.”
During fermentation, different foods are found to increase certain activities, thus conferring a number of benefits. In a paper published in Nutrients, the writers explained:6
“Fermentation was found to increase antioxidant activity of milks, cereals, fruit and vegetables, meat and fish. Anti-hypertensive peptides are detected in fermented milk and cereals. Changes in vitamin content are mainly observed in fermented milk and fruits.
Fermented milk and fruit juice were found to have probiotic activity. Other effects such as anti-diabetic properties, FODMAP reduction, and changes in fatty acid profile are peculiar of specific food categories.”
Fermented Foods Are High in Beneficial Bacteria
The transformation of the end product is not the only benefit associated with fermentation. The microorganisms responsible for fermenting are a focus of attention, as many are beneficial to your gut microbiome. In one study, researchers analyzed the microbial growth in “organically fermented vegetables, using a salt brine, which is a common ‘at-home’ method of food fermentation.”7
The researchers studied the microbial fermentation of beets, carrots, peppers and radishes. After collecting the data, they found the highest change in diversity of microbes was after two to three days. At the beginning of the process the microbiome of the food was similar to what would be found in the soil.
However, by the end of the first day, the microbes that dominated the fermented food were Enterobacteriaceae. As the process continued, the population of Lactobacillales grew. The microbes were compared to a sample that were first autoclaved and sterilized before the fermentation process. These samples showed little change. The authors wrote:8
“Spontaneous fermentations are known to be more challenging to control and many industrialized fermented food producers use starter cultures to directly manipulate fermentation outcomes … Our results indicate that the presumed nutritive and probiotic value of this process is highly dependent on the vegetable and microbiome that comes to dominate the process.”
The microbes living in your gut microbiome, both beneficial and pathogenic, are important to the stimulation of your immune system. Your gut has a strong impact on its stability. Researchers have found that dysbiosis can increase your “susceptibility to infections, hypersensitivity reactions, autoimmunity, chronic inflammation and cancer.”9
Your diet and the medications you take play a significant role in the development of dysbiosis. At the same time, probiotics have the potential to restore stability. I believe one of the best ways to get probiotic bacteria is through eating properly fermented foods.
Health Benefits of Fermented Foods
The health benefits associated with fermented foods are many. In fact, the yogurt industry has advertised that eating a container a day may be helpful in maintaining digestive health. However, while the product may have probiotics, it also contains an abundance of sugar that feeds the harmful bacteria in your gut. This is just one reason why store-bought yogurt is typically not beneficial.
Fermented foods promote bowel regularity and may be easier to digest. For instance, researchers have found that sourdough-fermented breads digest more easily than yeast breads. The authors of one study found that for those who ate the sour dough form, gastric emptying was faster, as was the transit time through the intestinal tract.10
Others discovered that bakery products made with sourdough promoted better gastrointestinal function then those that were prepared with brewer’s yeast.11 Fermented foods may help by reducing inflammation in the body and the gut. They also increase the bioaccessibility of polyphenols,12 which has a significant impact on mental health.13
Researchers have found fermented milk products to be helpful with certain conditions related to disease. In a study published in the BMJ, scientists evaluated two large groups of individuals from Sweden.14 There were 61,433 women and 45,339 men who responded to questionnaires. The researchers noted that a high intake of milk was associated with higher rates of mortality in men and women. However:
“Consumption of fermented milk products (soured milk and yogurt) indicated a negative relation with both the oxidative stress and the inflammatory markers …”15
Fermented foods may additionally play a role in the prevention of cancer.16 In lab studies, kombucha has shown the ability to preserve normal epithelial cells while selectively working against colon cancer. The researchers concluded:17
“Therefore, kombucha tea could be considered as a potential source of the antioxidation, inhibition of pathogenic enteric bacteria, and toxicity on colorectal cancer cells.”
As Chris Kresser, licensed integrative medicine clinician and co-director of the California Center for Functional Medicine writes, there are several more benefits to fermented foods. These include supporting skin health, protecting against food toxins and helping with weight management.18
Soy: Fermented or Unfermented?
Fermenting soybeans helps reduce their phytic acid levels. Phytic acid is a type of antinutrient that reduces your body’s ability to absorb minerals from your food. It binds to metal ions, preventing the absorption of certain minerals, including calcium, magnesium, iron and zinc19 — all of which are cofactors for optimal biochemistry in your body.
Zinc is especially important during flu season, as it helps suppress the replication of influenza. While unfermented soy products contain phytic acid, fermented soybeans have the ability to reduce mild cognitive impairment and raise brain-derived neurotrophic factor (BDNF).20
Fermented soy may also help lower the rate of death from cardiovascular disease in men and women. In one study using data conducted over the course of 14.8 years, researchers engaged 92,915 participants.21 They found those who had a lower risk of mortality consumed more fermented soy.
But the data did not reveal a statistically significant association between the total amount of soy products the participants ate and all-cause mortality. The researchers cautioned that the association may be reduced by factors that were not accounted for in the study. They hypothesize fermented soy is higher in fiber and potassium than non-fermented soy, which may help explain the difference in rates of heart disease.22
Tips for Making Fermented Foods at Home
In the U.S., it’s becoming more popular to eat fermented foods at home. Yet, preparing them is largely a lost art. One of the quickest and easiest ways to raise the level of your gut health is through your diet. For example, sugar is the preferred source of food for fungi and harmful bacteria.
On the other hand, probiotic-rich foods, such as fermented vegetables, will boost the population of beneficial bacteria, which then reduce the potentially pathogenic colonies. Making your own yogurt at home is an easy way to start with fermented foods.
Many of the yogurts sold on grocery store shelves are fruit flavored and sweetened with sugar. You’ll want to steer clear of commercial brands as they likely will not help promote an overall healthy gut flora. To make yogurt at home you only need a high-quality starter culture and raw, grass fed milk. You’ll find simple step-by-step instructions in “Benefits of Homemade Yogurt Versus Commercial.”
You can also experiment with fermenting almost any vegetable. Cucumbers (pickles) and cabbage (sauerkraut) are among the most popular. Although it might seem intimidating at first, once you have the basic method down, it’s not difficult. In the video below, Julie and I review how to do this.
As I discuss in “Tips for Fermenting at Home,” there are several steps you can take to make the process a little easier. Begin with fresh, organic ingredients and be sure to wash them properly under cold running water. The idea is to remove bacteria, enzymes and other debris as this can affect the outcome. Never use plastic because it can leach chemicals into the food.
Don’t use metal, since the salt that’s used in the fermentation process can corrode the container. Instead, choose glass Mason jars with self-sealing lids. Most fermented vegetables will need to be covered with brine.
The process of wild fermentation is not consistent so you may want to use a starter culture on its own or in addition to salt. I recommend using a vitamin K2-rich starter culture dissolved in celery juice.
Allow the jars to sit in a relatively warm area for several days. The temperature should ideally be around 72 degrees Fahrenheit. During the summer months, vegetables are typically finished in three to four days. In the winter, they may need up to seven days. The only way to tell when the fermentation process is complete is to open the jar and have a taste.
When you’re happy with the flavor and consistency, move the jars into the refrigerator. Refrigeration will slow fermentation and the vegetables can keep for many months. Remember not to eat out of the jar because you’ll contaminate the rest of the batch with the bacteria from your mouth. Make sure the vegetables are covered with brine before replacing the lid.