A Guide to Fermented Foods


Fermented Foods

Fermented foods have continued to rise in interest over the past couple of years and this is due to more evidence showing their beneficial impact on our gut health.

The process which occurs during fermentation promotes the growth of good bacteria which help to maintain and improve intestinal health.

By having a healthy gut, not only does it help with ensuring that we are able to absorb the nutrients in our food more efficiently but it also has an impact on our overall health.

Fermentation is a great way to naturally enrich foods with vitamins, minerals and essential amino acids biologically, rather than synthetically adding them into foods. It is also a way to help preserve foods, in cases where it may not be possible to successfully store foods (Steinkraus, 1994).

Historical Use of Fermentation

Fermentation has been used over the centuries as a natural way to preserve foods to stop them going off.

This is obtained by utilising the good bacteria within foods. During times where there was no refrigerator to keep things edible, it was a useful process to use and it was not just the fermented foods we see around today.

Alcohol is created through fermentation, as well as breads, cheese, meats, and grains. It has been found that fermented drinks were most likely produced and consumed over 7,000 years ago in Babylon (Iraq), 5,000 years ago in Egypt, 4,000 in Mexico, and 3,500 years ago in Sudan (cited from Battcock and Azam-Ali, 1998).

The production of bread is believed to have begun in Egypt, dating back to 3,500 years ago, with loaves being found in tombs.

Bread Pudding

It is believed that China was where fermented vegetables were first introduced into the diet, with references to fermented grains being written in a book in the Chou dynasty (1121-256 BC) (Battcock and Azam-Ali, 1998).

The use of fermentation through history and the foods and drinks it creates, are associated with both tradition and culture within those communities. It’s been passed down through these communities, with this knowledge still being used today.

Fermentation Processes

Fermentation is defined as an anaerobic (without oxygen) cellular process where organic foods are converted into simpler compounds and chimerical energy is produced (Biology Online, 2008). During the process of fermentation, the microorganisms break down the sugars and starches found in food into lactic and acetic which are alcohols and acids.

Lacto-fermentation is one type of fermentation process which can be used. This is when vegetables are soaked in salt water, or their own juice and this allows the good bacteria to grow, whilst preventing harmful organisms to grow as well during the process. The bacteria eat the sugars contained in the vegetables, which leads to the production of lactic acid, which causes the sour taste from fermented veg.

Ethyl alcohol fermentation – within this fermentation process, carbohydrates are converted into alcohol.

Acetic fermentation is the process where vinegar is formed and is produced when alcohol is exposed to air and converted to acetic acid (i.e. vinegar).

Throughout the fermentation process, it is enzymes and the activity they create which enables the changes, helping to both start and control reactions.

What Helps Aid the Process of Fermentation?

When fermenting foods, you can either use microorganisms; yeast; or bacteria to make the process happen.

With reference to bacteria in fermentation, it’s the lactobacillaceae family which provide some important bacteria. These produce the lactic acid from carbohydrates. When fermenting fruits and vegetables the bacteria is acetobacter which enables the production of acetic acid (Battcock and Azam-Ali, 1998).

Gluten Free Bread Loaf with Turmeric

Yeasts can both positively and negatively impact the effect of food. Yeasts are larger than most bacteria and play an important role within the food industry – this is due to the effect of the enzymes which give chemical reactions, such as within breads, allowing it to ferment and rise (leavening), and helping produce alcohol and invert sugars (forms them into syrups) (Battcock and Azam-Ali, 1998).

Probiotics, Prebiotics and Antibiotics – What’s the Difference?

Whilst we use antibiotics to kill the bacteria when we have picked up a pathogen, we have prebiotics and probiotics to promote beneficial bacteria within our gut.

Antibiotics work in the way that they kill or prevent bacteria from reproducing and can completely change our gut flora (gut flora is the beneficial microbes which are found within our gut (Singh et al., 2017)). This gut flora then needs to recover, including the good bacteria which was there before the antibiotics.

Probiotics are living bacteria that we are able to consume, which improve our overall health.

Whilst prebiotics are foods which we consume and are not digested, so pass through to the large intestine where the beneficial bacteria in the large intestines can feed off of it. This enables these bacteria to thrive in comparison to the bad bacteria.

What Category Does Fibre Fall Into?

Fibre is known as a prebiotic. From above we know that fibre, therefore, is food that we consume that we are unable to digest. However, it feeds the bacteria in the large intestine allowing them to thrive and continue their beneficial impact on our health.

Apple and Berry Coconut Crumble using fibre-rich coconut flour

It has been found in mice that when they were fed a diet low in soluble fibre the mice had poor gut health and inflammation in their intestines. When fibre was re-introduced, the health of their gut was restored. If you want to read more about this study and its findings in more detail click here.

Studies have indicated that a high fibre diet may also help ease gout which has been discussed here, along with foods which are high in fibre. It has also been shown that a high fibre diet is associated with lower risks of heart disease, which is available here.

High fibre diets have been associated with a decreased risk of cardiovascular disease, type 2 diabetes, and in some cases some forms of cancer. It may also help lower blood pressure and reduce weight gain (Dahl et al., 2017). It has also been shown to produce some anti-inflammatory effects which is discussed in the blog above about fibre helping to ease gout.

Different Types of Fermented Foods

There are many different types of fermented foods – far more than just these ones that I’ve included here.

Different cultures and even within families, have a variety of recipes and ingredients to make their own fermented foods. These are all known to be probiotics, helping the flora of our intestines remain healthy with good bacteria.

A fermented food is sauerkraut, a form of preserved cabbage
  • Sauerkraut is created with cabbage, one of the more well-known forms of preserved cabbage. Some of the nutrients which are found in sauerkraut include a large quantity of lactic acid; the B vitamins; vitamin A, C, and K; and minerals. The inclusion of sauerkraut in the diet can be traced back to 4th century BC and even Hippocrates described it as a health food and a medicinal remedy. It was also used by those who were at sea, due to being so high in vitamins and because it helped prevent scurvy, a common issue with those who were at sea (Raak et al., 2014). It is thought that regular intake of small doses of sauerkraut has a positive effect on our gastrointestinal tract. If you are taking MAOIs for depression, anxiety disorders, obsessive compulsive disorders and Parkinson’s disease, sauerkraut is on the MAOI diet-restricted food list (Raak et al., 2014).
  • Kimchi is a popular traditional Korean dish which involves the fermentation of cabbage with other vegetables with lactic acid bacteria. The inclusion of other vegetables allows there to be an enrichment of more vitamins and minerals than if there was just cabbage alone, increasing its functional uses. Information on kimchi was written in a book from 1145AD called Samkuksaki, where the cabbage was fermented in brine water in a stone jar. The vegetables which are used in the kimchi will, therefore, vary the increases in nutritional value, but may increase vitamin C; B vitamins; minerals including, potassium, calcium, and iron; fibre; vitamin A; and other compounds (Patra et al., 2016). Usually radish, garlic and onion are added to kimchi, all with their own health benefits, due to being a source of phytochemicals and have an anti-inflammatory effect and potentially having cardio protective and anti-cancer effect on our body (Patra et al., 2016). The consumption of kimchi has shown to have a positive effect on decreasing insulin resistance but increase insulin sensitivity and decrease in blood pressure, in those who were deemed to be pre-diabetic (An et al., 2013). A small scale study found that consuming kimchi helped improve the intestinal bacteria and was as beneficial as taking dietary supplements (Kim et al., 2016a).
  • Kefir – traditionally kefir is made with cow’s milk but now there is a variety of different sources including goat, sheep, soy and coconut milk. To make kefir you need the kefir grain for the fermentation and population of yeast (Bourrie et al., 2016). A small scale systematic review found and suggested that it may also have some anticancer effects, due to the active compounds in it, including peptides, and polysaccharides (Rafie et al., 2015). Regular consumption of kefir has been linked to improved antimicrobial activity, improved gut health, anti-carcinogenic effects, helps control serum glucose and cholesterol and improving immune system (Ahmed et al., 2013, and Bourrie et al., 2016). When fermenting with kefir and milk, the bacteria actually removes the lactose in milk, which enables those who are lactose intolerant to be able to consume it (Ahmed et al., 2013). It has also been indicated that a kefir culture with soy milk could work as a complimentary therapy for postprandial hyperglycaemia which is linked to the management of type 2 diabetes (Kwon et al., 2006).
Miso Baked Aubergine
  • Soy beans – miso is a Japanese seasoning, which is produced by fermenting soybeans, with other ingredients, depending on the type of miso which is wanted to be achieved. Other types of fermented foods from soy beans include tempeh and soy sauce. This leads to a paste being formed which is then added into a variety of recipes. It has been found within reviews that although results can vary between studies that the consumption of soy foods can increase Bifidobacterium and lactobacilli. This helps reduce the pathogenic bacteria (bad bacteria) and improve the good bacteria, which has a beneficial impact on our health (Huang et al., 2016). It has been suggested that fermented soy bean products may help to prevent or reduce the progression of type 2 diabetes, although this is not a definite conclusion that this is 100% effective (Kwon et al., 2010).

What Are the Benefits of Fermented Foods?

Fermented foods are probiotics. They are excellent for our gut health and enable us to have a healthy and thriving gut flora, which in itself enables us to absorb more nutrients.

Not only does it help with our gut flora through being a probiotic helping to achieve the correct balance of bacteria found within the gut, but the lactic acid formed and enzymes allow vitamins and minerals to be more easily absorbed into our body, where we can use them to maintain and enhance our health.

One of the main things which is a benefit of fermented produce is that this process actually increases the vitamins and minerals in the foods, which means that we are able to absorb more nutrients. Some of the main vitamins which benefit from the process is vitamin C, and some of the B vitamins including folic acid, riboflavin, niacin, thiamine and biotin.

Love your gut

Even from above, looking at the couple of examples of fermented foods and their perceived health benefits, we can see that there is a whole array of nutritional health benefits which can be associated with a diet that includes fermented foods.

More and more has come out, linking our digestive tract health to our overall health, and that if our digestive tract health is out of sync, it can lead to damage and illness.

It has been discussed how our intestinal microbiota actually have a dietary impact on the host’s metabolic status, which means that it is linked to obesity, type 2 diabetes, and other metabolic diseases (Sonnenburg and Bäckhed, 2016).

The microbiome found within our intestines, help to modulate the maturation and function of the immune cells which are found within our tissue in the central nervous system.

They also play a role within the peripheral nervous system in regards to the immune cells there, which regulate our response to neuroinflammation, autoimmunity and neurogenesis (Fung et al., 2017). Many of the cells of our innate immune system are found within this area, affecting our metabolism, immunity and how successfully we respond to infections (Thaiss et al., 2016).

If our microbiome is in dysbiosis (where the microbial balance is impaired), it can end up leading to the triggering of immune disorders, preventing them from being able to modulate or prevent inflammatory diseases (Honda and Littman, 2016)

Brain and Cognitive Function

Research is being looked at now, discussing how our gut and our brain interact with each other on a level not previously thought.

It has been shown that when the gut is in a state of dysbiosis, it has been shown to be linked to anxiety and depression within animal studies (Kim et al., 2016b. and Luna and Foster, 2015).

In a human study, it has been shown that the consumption of fermented foods has helped to show that those who are at higher risk of social anxiety symptoms from their neuroticism, actually showed fewer anxiety symptoms when they consumed fermented foods. The study suggested that the probiotics which are found in fermented foods may help to reduce the symptoms of social anxiety (Hilimire et al., 2015).

It is believed that even though this research is within its early stages of knowledge, our gut flora does have an influence on not only brain development, but our behaviour and mood, as well. It also demonstrates that our gut flora is impacted by stress (Dash et al., 2015).

Fermented dairy products have been shown to prevent neurotoxicity, indicating that they have a neuroprotective effect to them, as well as being found to decrease salivary cortisol in healthy subjects who were shown stressful situations (Kim et al., 2016b).

A small scale study which looked at how fermented milk products with probiotics affected the brain’s response to central processing of emotion and sensation, found that women that were given the fermented milk instead of the non-fermented had affected the activity of the brain during an MRI scan compared to those who had non-fermented (Tillisch et al., 2013).

Research around fermented food, gut health, and brain and cognitive function is still an emerging area with more research needed to find a clearer answer. It appears that it does have an impact on our brain and cognitive health and is therefore an area of great importance.


I mean I could go on and on about all the research which is coming out looking at this and our gut here but I mean it’s really a whole series worth of stuff!

There’s some excellent books out there which talk about the importance of a healthy gut. If you are really interested in your gut health and how it can impact our health overall, I would highly recommend a book called “Gut: the Inside Story of our Body’s Most Under-rated Organ” by Giulia Enders. It’s a great read and really interesting.

The continuous use of antibiotics can lead to resistance of pathogenic bacteria, affecting the microbiota of the intestinal tract, increasing that population of bacteria and leading to ill health. This isn’t saying antibiotics are bad, but is important to only use them when given to by a doctor, and to always finish the pack. By leaving any behind it means that you may not have removed all of the bacteria which caused the illness leading to resistance and maybe a recurrent issue with that illness.

If fermented foods aren’t your cup of tea, you can always look at supplementing with probiotics but it’s always important to research around this and find supplements which have a great reviews and work! Having a healthy gut flora is a way that you can increase your absorption of vitamins and minerals, helping you to maintain a healthy body.

I hope this has been of some interest for you all and I haven’t gone off topic too much. It’s been amazing researching around the topic and something I myself want to look much more into.

If we care for our gut and give it the right foods to run at an optimal level, it shows that it can have an overall impact not just on our gut health but our energy, our mood, how well our immune system responds and even brain functioning.


Ahmed, Z. Wang, Y. Ahmad, A. Khan, ST. Ahmad, H. and Afreen, A. (2013). Kefir and health: a contemporary perspective. Critical Reviews in Food Science and Nutrition, 53(5), pp. 422-434. Available here.

An, SY. Lee, MS. Jeon, JY. Ha, ES. Kim, TH. Yoon, JY. Ok, CO. Lee, HK. Hwang, WS. Choe, SJ. Han, SJ. Kim, DJ. and Lee, KW. (2013). Beneficial effects of fresh and fermented kimchi in prediabetic individuals. Annals of Nutrition and Medicine, 63(1-2), pp. 111-119. Available here.

Battcock, M. and Azam-Ali, S. (1998). Fermented fruits and vegetables a global perspective. Food and Agriculture Organization of the United Nations Rome. FAO Agricultural Services Bulletin no. 134. Available here.

Biology Online. (2008). Fermentation. Available here.

Bourrie, BCT. Willing, BP. and Cotter, PD. (2016). The microbiota and health promoting characteristics of the fermented beverage kefir. Frontiers in Microbiology, 7(647). Available here.

Dahl, WJ. Agro, NC. Eliasson, ÅM. Mialki, KL. Olivera, JD. Rusch, CT. and Young, CN. Health benefits of fibre fermentation. The Journal of the American College of Nutrition, pp. 1-10. Available here.

Dash, S. Clarke, G. Berk, M. and Jacka, FN. (2015). The gut microbiome and diet in psychiatry: focus on depression. Current Opinion in Psychiatry, 28(1), pp. 1-6. Available here.

Fung, TC. Olson, CA. and Hsiao, EY. (2017). Interactions between the microbiota, immune and nervous systems in health and disease. Nature neuroscience. Available here.

Hilimire, MR. DeVylder, JE. And Forestell, CA. (2015). Fermented foods, neuroticism, and social anxiety: an interaction model. Psychiatry Research, 228, pp. 203-208. Available here.

Honda, K. and Littman, DR. (2016). The microbiota in adaptive immune homeostasis and disease. Nature, 535(7610), pp. 75-84. Available here.

Huang, H. Krishnan, HB. Pham, Q. Yu, LL. And Wang, TT. (2016). Soy and gut microbiota: interaction and implication for human health. Journal of Agriculture and Food Chemistry, 64(46), pp. 8695-8709. Available here.

Kim, JY. Choi, EY. Hong, YH. Song, YO. Han, JS. Lee, SS. Han, ES. Kim, TW. Choi, IS. Cho, KK. (2016a). Changes in Korean adult females intestinal microbiota resulting from kimchi intake. Journal of Nutrition & Food Sciences. Available here.

Kim, B. Hong, VM. Yang, J. Hyun, H. Im, JJ. Hwang, J. Yoon, S. and Kim, JE. (2016b). A review of fermented foods with beneficial effects on brain and cognitive function. Preventive Nutrition and Food Science, 21(4), pp. 297-309. Available here.

Kwon, YI. Apostolidis, E. and Shetty, K. (2006). Anti-diabetes functionality of kefir culture-mediated fermented soymilk supplemented with rhodiola extracts. Food Biotechnology, 20(1). Available here.

Kwon, DY. Daily, JW. Kim, HJ. And Park, S. (2010). Antidiabetic effects of fermented soybean products on type 2 diabetes. Nutrition Research, 30(1), pp. 1-13. Available here.

Luna, RA. And Foster, JA. (2015). Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression. Current Opinion in Biotechnology, 32, pp. 35-41. Available here.

Patra, JK. Das, G. Paramithiotis, S. and Shin, HS. (2016). Kimchi and other widely consumed traditional fermented foods of Korea: a review. Frontiers in Microbiology, 7(1493). Available here.

Raak, C. Ostermann, T. Boehm, K. and Molsberger, F. (2014). Regular consumption of sauerkraut and its effect on human health: a bibliometric analysis. Global Advances in Health and Medicine, 3(6), pp-12-18. Available here.

Rafie, N. Golpour Hamedani, S. Ghiasvand, R. and Miraghajani, M. (2015). Kefir and cancer: a systemtic review of literatures. Archives of Iranian Medicine, 18(12), pp.852-857. Available here.

Singh, SB. Young, K. and Silver, LL. (2017). What is an “ideal” antibiotic? Discovery challenges and path forward. Biochemical Pharmacology. Available here.

Sonnenburg, JL. And Bäckhed, F. (2016). Diet-microbiota interactions as moderators of human metabolism. Nature, 535(7610), pp. 56-64. Available here.

Steinkraus, KH. (1994). Nutritional significance of fermented foods. Food Research International, 27(3), pp. 259-267. Available here.

Thaiss, CA. Zmora, N. Levy, M. and Elinav, E. (2016). The microbiome and innate immunity. Nature, 535(7610), pp. 65-74. Available here.

Tillisch, K. Labus, J. Kilpatrick, L. Jiang, Z. Stains, J. Ebrat, B. Guyonnet, D. Legrain-Raspaud, S. Trotin, B.Naliboff, B. and Mayer, EA. (2013). Consumption of fermented milk product with probiotic modulates brain activity. Gastroenterology, 144(7), pp. 1394-1401. Available here.

About Lucy Bee Limited

Lucy Bee is concerned with Fair Trade, ethical and sustainable living, recycling and eating close to nature with additive free products for health.

Members of the Lucy Bee team are not medically trained and can only offer their best advice. Any information provided by us is not intended to diagnose, treat, cure or prevent disease.

Please note you should always refer your health queries to a qualified medical practitioner.

Daisy has a Master’s Degree in Public Health Nutrition, which is Association for Nutrition (AFN) accredited. She, also, has a BSc degree in Psychology and Cognitive Neuroscience; and has completed an AFN accredited Diet Specialist Nutrition course. She is Lucy’s sister and is the Lucy Bee voice on all aspects of nutrition and its effect on the body. In addition to this, Daisy is shadowing a nutritionist in Harley Street and working for an NHS funded project, The Diabetes Prevention Programme.