The Power of Fermentation
Fermented foods and beverages were among the first processed food products consumed by humans. The production of foods such as yogurt, kefir, wine, beer, sauerkraut and kimchi were initially valued for their improved shelf life, safety, and flavour. It is now understood that fermented foods improve digestibility and contribute beneficial microorganisms similar to, but more diverse than, strains used in probiotic supplements (1). Modern research is beginning to show that fermented foods provide nutritional and functional properties well beyond the original food. Indeed, fermented foods may become increasingly important medicinally with the emergence of antibiotic resistant pathogens.
Fermentation as Preservation
Fermentation usually involves a symbiotic combination of bacteria and yeasts. The lactic acid producing bacteria found in many ferments are thought to exert their preservative activity through the production of anti-microbial metabolites which control the growth of pathogens that would otherwise make the food spoil.
As world population increases, lactic acid fermentation is expected to play an important role in preserving fresh vegetables, fruits, and other foods in order to feed people in developing countries. This is particularly critical in tropical and subtropical areas where the climate favours the growth of microorganisms that quickly cause foods to spoil (2).
Nowadays we are out of the habit of planning ahead for times of hardship. However, be it for reasons of food security or for their health benefits it is well worth including some fermented foods in your diet.
The Many Types of Fermented Foods
The fermented foods we are most familiar with in the UK are probably yoghurt, beer, bread, wine and vinegar. In addition, health food shops have been providing the initiated with miso, tempeh and tamari from Japan for the past few decades. But these are only a tiny proportion of the wide range of fermented foods available in different cultures around the world. Fermented vegetable dishes include sauerkraut, kimchi, gundruk, khalpi and sinki. Fermented drinks include kefir, kvass, kombucha and hardaliye (3). Fermented grains, pulses, nuts, seeds, meat and fish are also becoming increasingly popular as the enthusiasm for fermentation grows.
Fermentation and the Gut Microbiome
As human beings we have up to 2kg of microbes in our digestive tracts. There are thought to be more microbes in the gut than there are cells in the body! These organisms are collectively referred to as the microbiome. It is now understood that each person’s microbiome is unique to them and that the greater the diversity of organisms one has in their microbiome the better. The bacteria in the gut play an important role in releasing, and even synthesising nutrients from food, including some B vitamins and vitamin K2. There is increasing evidence that the balance of organisms in the microbiome affects many aspects of health including metabolism, weight, mental health, mood, memory, learning, and the immune system.
The food we eat is one of the main factors that influences the balance of organisms in the microbiome. Eating fermented foods is one of the quickest ways of increasing the range of beneficial organisms that take up residence in, or pass through, the gut. You’ve probably heard of probiotics and prebiotics which have been used for decades to support the health of the microbiome. Probiotics are used to improve microbial balance and aid digestion (4), whilst prebiotics support the growth of beneficial bacteria in the gut. Fermented foods contain both probiotics and prebiotics giving them antimicrobial, cardio-protective and antioxidant properties (5).
Consumption of fermented foods is associated with an array of health benefits (6,7):
- Immunomodulatory effects
- Anti-allergenic activities
- Anti-atherosclerotic activity
- Anti-aging benefits some of which have been attributed to specific compounds such as genistein and daidzein in soybeans.
Here’s a quick look at some specific effects of fermented foods.
Fermented foods and digestion
Kefir has been shown to improve lactose digestion and tolerance in adults with lactose maldigestion (8). In addition research has found that milk fermented with Bifidobacteria, as in some yoghurts, has the potential to alleviate gastric symptoms in subjects taking no medication (9).
Fermented Foods and Brain Health
With recent advances in the understanding of gut-brain interactions and the effect of the microbiome on mental health there is early research indicating that fermented foods may have neuroprotective effects which could lead to cognitive improvements (10).
Fermented Foods and Skin Health
There is growing evidence that the effects of fermented dairy products on the microbiota in the gastrointestinal tract can improve skin health, when used both topically and orally (11).
Fermented Foods and the Immune System
Kefir has been associated with antimicrobial activity, immunomodulation, anti-oxidative effects, anti-allergenic effects, and tumor suppression (12).
Fermented Foods and Autoimmune Diseases
The balance of organisms in the gut affects the pathogenesis of several autoimmune diseases due to their influence on the immune system. Research investigating the modulatory effects of various dietary yeasts and lactic acid bacteria contained in fermented foods on the microbiota found that fermented foods may be beneficial for people with autoimmune diseases such as MS (13).
1. Curr Opin Biotechnol. 2016 Dec 17;44:94-102. Health benefits of fermented foods: microbiota and beyond. Marco ML, Heeney D, Binda S, Cifelli CJ et al.
2. Biotech Res Int. 2014;2014:250424. Fermented fruits and vegetables of Asia: a potential source of probiotics. Swain MR, Anandharaj M, Ray RC et al.
3. Nutr Res Rev. 2017 Jan 24:1-24. Traditional low-alcoholic and non-alcoholic fermented beverages consumed in European countries: a neglected food group. Baschali A, Tsakalidou E, Kyriacou A et al.
4. Bioengineered. 2016;7(1):11-20. Beneficial Microbes: The pharmacy in the gut. Linares DM, Ross P, Stanton C.
5. Front Microbiol. 2016 Apr 26;7:578. Functional Properties of Microorganisms in Fermented Foods. Tamang JP, Shin DH, Jung SJ, Chae SW.
6. Food Res Int. 2020 Aug;134:109269. Traditional fermented foods with anti-aging effect: A concentric review Das G et al.
7. Crit Rev Food Sci Nutr 2019;59(3):506-527. Health benefits of fermented foods. Sanlier N et al.
8. J Am Diet Assoc. 2003 May;103(5):582-7. Kefir improves lactose digestion and tolerance in adults with lactose maldigestion. Hertzler SR, Clancy SM.
9. J Dairy Sci. 2015 Apr;98(4):2277-83. Health benefits of fermented milk containing Bifidobacterium bifidum YIT 10347 on gastric symptoms in adults. Gomi A, Lino T, Nonaka C et al.
10. Prev Nutr Food Sci. 2016 Dec;21(4):297-309. A Review of Fermented Foods with Beneficial Effects on Brain and Cognitive Function. Kim B, Hong VM, Yang J, Hyun H. et al.
11. J Altern Complement Med. 2015 Jul;21(7):380-5. Effects of Fermented Dairy Products on Skin: A Systematic Review. Vaughn AR, Sivamani RK.
12. Nutrients. 2019 Jun 1;11(6):1252. Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir. Slattery C et al.
13. Ann Clin Transl Neurol. 2015 Jan;2(1):56-66. Dietary Yeasts Reduce Inflammation in Central Nerve System via Microflora. Takata K, Tomita T, Okuno T, Kinoshita M, et al.