Health Benefits of Eating Fermented Foods

We're more microbe than we are person: Our bodies contain 10 times more bacteria than cells, meaning around 100 trillion microbes are crawling inside and on us. By far the largest collection—about 3 pounds' worth—hangs out in the stomach and intestines.

Video 1.  How Italian Gorgonzola Cheese Is Made | Regional Eats (YouTube link)

While historical evidence has linked harmful gut bacteria to everything from increasing diabetes risk to the formation of autoimmune diseases,^[24]  healthy gut bacteria are now being hailed as a possible solution in disease prevention.  One way to make your gut healthy is by consuming fermented foods—From Korean kimchi, Japanese tsukemono, Indian chutneys to the ubiquitous sauerkraut, yogurt and cheese, global cultures have crafted unique flavors and traditions around fermentation.

In this article, we will discuss the history of fermented foods and their potential health benefits.

History of Fermented Foods^[17]

The earliest record of fermentation dates back as far as 6000 B.C. in the Fertile Crescent—and nearly every civilization since has included at least one fermented food in its culinary heritage.  In some places they make up a 5% of daily intake, while in others their role can be as substantial as 40%. However, their global consumption is declining as traditional food systems give way to the influence of a western diet and fast foods.^[19]

Using locally available raw materials from plant or animal sources, people across the globe produce this type of food and drink either naturally or by adding starter cultures that contain micro-organisms. Micro-organisms transform these raw materials both biochemically (i.e., the nutrients) and organoleptically (i.e., the taste/texture/odor) into fermented foods. For example, sourdough belongs to the entire world. Until 160 years ago, everyone who was making bread was using sourdough.^[32]

Links between fermented foods and health can be traced as far back as ancient Rome and China, and remain an area of great interest for researchers in modern times. Asian civilizations in particular have a history of fermenting a wide variety of foods—Japanese natto (soybeans), Vietnamese mám (seafood), Chinese douchi (black beans), Lao pa daek (fish sauce), Korean banchan (side dishes)—that remain essential components of their everyday cuisine.

In some cases, fermentation is a critical component to food safety beyond preservation. In West African countries, garri is an important food source. It is made from the root vegetable cassava, which contains natural cyanides and, if not properly fermented, can be poisonous. Other foods, such as the Tanzanian fermented gruel togwa, have been found to protect against foodborne illnesses in regions that have poor sanitation.

Figure 1.  Putative mechanisms of fermented or Brassica vegetables against COVID-19. (A) Oxidative stress induced by SARS-CoV-2 after its binding to ACE2. (B) Preventive effects of cabbage and fermented vegetables through Nrf2 (Source: [40])

 

Health Benefits of Fermented Foods

"Let food be your medicine and your medicine be your food" – Hippocrates

"Fermented foods are potent chelators (detoxifiers) and contain much higher levels of probiotics than probiotic supplements, making them ideal for optimizing your gut flora." said Dr. Mercola.^[4,11] Because of their probiotic properties, including attachment to epithelial cells, immunomodulation, and competitive exclusion of pathogens, numerous probiotic microorganisms (e.g. Lactobacillus rhamnosus GG, L. reuteri, bifidobacteria and certain strains of L. casei or the L. acidophilus-group) are being intensively studied.^[25]

Potential health benefits of fermented foods include:

• Modulate intestinal microbiota 
• Peptides, bioactive compounds and strains occurring in kefir, can modulate gut microbiota composition, low-grade inflammation and intestinal permeability, which consequently may generate health benefits.^[37,38]
• Improve skin condition
• A study showed a significant improvement on all skin outcomes and suggest that atopical individuals may benefit from kefir intake, especially regarding their skin hydration.^[45]
• Help fight depression
• Consuming lactic acid bacteria may help fight depression and increase production of chemicals that control emotions, according to a researcher at National Yang Ming University.^[14]
• One type of sourdough bacteria, Lactobacillus reuteri, activates the gut-brain axis by stimulating the brain to release the social hormone oxytocin.^[35]
• Help immunity
• Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, also potent Nrf2 activators. It is proposed that fermented cabbage may enhance Nrf2-associated antioxidant effects, which is helpful in mitigating COVID-19 severity.^[40]
• Among the numerous purported health benefits attributed to probiotic bacteria, the (transient) modulation of the intestinal microflora of the host and the capacity to interact with the immune system directly or mediated by the autochthonous microflora, are basic mechanisms.^[25,38]
• Enrich food with essential amino acids, vitamins, mineral and bioactive compounds
• During tempeh fermentation, vitamins like niacin and riboflavin are increased by using the starter culture Rhizopus oligosporus. 
• Thiamine and riboflavin increase during fermentation of idli, the fermented rice and black-gram (a type of legume) product of India and Sri Lanka.
• Pulque — one of the oldest alcoholic beverages prepared from the juices of cactus plants in Mexico — is rich in vitamins such as thiamine, riboflavin, niacin and biotin.^[1]
• Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration.^[21,22]
• Help competitive exclusion of pathogens
• Help lower bone fracture risk
• A research in Japan has suggested the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.^[22]
• Meta-analysis of human studies indicated that probiotic consumption has significantly increased serum and urinary calcium levels and decreased PTH level.^[39]
• Note that increasing PTH level leads to more bone destruction by osteoclasts. 
• Help lower blood pressure 
• Research led by Jing Sun, PhD, of the Griffith Health Institute and School of Medicine at Griffith University in Australia, suggests that consuming probiotics from food sources and dietary supplements may improve blood pressure.^[16]
• Degrade anti-nutritive compounds
• Make foods edible
• In the fermentation process, micro-organisms can be coaxed into producing enzymes, which degrade anti-nutritive compounds and thereby make edible.
• Yogurt or Kefir (i.e., fermented milk) may help alleviate the symptoms of lactose malabsorption.^[1]
• The cultures used in making yoghurt and curds, contain substantial quantities of ß-D-galactosidase, something that is thought to help alleviate the symptoms of lactose malabsorption. 
• Yogurt, as a viscous food, may delay the stomach emptying and that way help lessen lactose intolerant symptoms.
• Bitter varieties of cassava tubers contain a potentially poisonous substance that can be detoxified via lactic acid bacteria, as in gari and fufu, fermented cassava root products from Africa.^[1]
• The fermentation process in soy beans removes the phytates, trypsin inhibitors and hemaglutinin.^[3]
• Make food with enhanced flavor and aroma
• Make foods more digestible
• The soy carbohydrates in tempeh become more digestible as a result of the fermentation process. In particular, the oligosaccharides associated with gas and indigestion are greatly reduced by the Rhizopus culture.
• Fermented soy products have more bioactive molecules than those that are non-fermented. This is because beta glucosidase from bacteria cleaves sugar off isoflavones in soy, converting them into the active compounds diadzein, genistein, and glycetein.

Photo Credit

• 李金明人物油畫

References

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5. Doenjang
• In traditional Korean cuisine, jukyeom (죽염, 竹鹽), which means "bamboo salt", is prepared by roasting salt at temperatures between 800 and 2000 °C^[12] in a bamboo container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud, and has been shown to increase the anticlastogenic and antimutagenic properties of the fermented soybean paste known in Korea as doenjang.
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• Traditional fermented foods in Turkey include fermented milks (yoghurt, torba yoghurt, kurut, ayran, kefir, koumiss), cereal-based fermented food (tarhana), and non-alcoholic beverage (boza), fermented fruits, and vegetables (turşu, şalgam, hardaliye), and fermented meat (sucuk). 
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• In general, fermentation of carbohydrates is considered to be beneficial, whereas fermentation of proteinaceous material (putrefaction) is considered to be detrimental.
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33. 9 Delicious Probiotic-Rich Foods (That Aren’t Yogurt)
34. Fermented or Unfermented Soy Foods for Prostate Cancer Prevention?
• The answer is unfermented soy foods.  So, for prostate cancer prevention, you want to go for unfermented soy foods.
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• One type of sourdough bacteria, Lactobacillus reuteri, has remarkable health functions. It has been shown to improve immunity and suppress tumor development. L. reuteri also reduces weight gain and can speed wound healing.
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46. Partial to Pickles? (Dr. Andrew Weil)
• I’m a big fan of pickled foods, but I prefer the ones that have been naturally fermented and contain live organisms.