Aside from a pint of refreshing fermented barley on a summers afternoon, or a glass of fermented grape juice on a Sunday evening, fermented foods don’t play much of a part in a Western diet. In fact, they are often thought of with a bit of distaste because the term ‘ferment’ conjurers up images of rotting and decomposing foods, all of which we habitually avoid. However, fermented food is something that other cultures embrace and eat regularly because they offer some unique health benefits and can even be tasty (even if the taste can be somewhat acquired). So here I’ll explain what fermentation does to foods, why you should eat more and even give you some suggestions.


What is fermentation?

Fermentation by definition is the chemical breakdown of a substance by bacteria, yeasts, or other micro-organisms. In the vast majority of circumstances, it requires carbohydrates in some form for the bacteria to metabolize, and yes, this is very very similar to rotting. The only real difference between the two is fermentation is something that is controlled to some extent (either by choosing the bacteria used, or the conditions it is kept in), whereas ‘rotting’ is uncontrolled and often a result of the food being neglected.

The important difference is the control. With fermented foods, we know which bacteria is causing the fermentation, we know what chemicals it gives off, and we know it is safe to eat. Although rotting food undergoes a similar process, eating rotten food is like playing Russian roulette. You have no idea what is breaking down the food or what chemicals are being produced, and more importantly, you have no idea what they do inside your body.

Still, fermentation sounds a bit gross, and it still begs the question of why would you want to eat food that has been partially digested by bacteria, when you are constantly told that fresh food is the most nutritious and bacteria are unhygienic/ make you ill?


Why eat fermented food?

Bacteria produce additional nutrients – This is the case for many types of fermented foods, but one of the best examples is a type of fermented soya bean called natto. Fermented soya bean doesn’t have the same health concerns that unfermented soya does, and is one of the highest sources of vitamin K2– a very important vitamin for blood and bone health. Both vitamin K1 and K2 are rare in modern diets, which makes fermented foods like this very valuable.

The bacteria don’t just produce vitamin K2 though. They can produce a whole host of other nutrients depending on the types of bacteria used, and can offer a number of benefits.

Pre-digested is good – Yes it sounds off putting, but having parts of your foods pre-digested can be very good. It can make certain nutrients more bio-available, and an example of this is the production of fermented cod liver oil. When the livers are fermenting the bacteria break down the liver cell walls to release the omega-3 fatty acids, and they can even cleave some of the omega-3 fatty acids from the glycerol backbone to allow greater absorption in the digestive system. All without any heat or chemicals.

In addition to this, the bacteria can even digest unwanted nutrients.  A great example is kefir, where the bacteria break down the lactose which allows lactose intolerant people to enjoy it.

Probiotic – Fermented foods will generally contain the bacteria that fermented them. There are some exceptions, but generally, when you eat fermented food, you eat the bacteria, and these bacteria are usually probiotics. The benefits from these bacteria can range from reducing inflammation, supporting the immune system and producing additional nutrients in the digestive tract. Most fermented foods are produced by lacto-fermentation, which uses one of the most researched probiotic species of bacteria called Lactobacillius. You will find this species of bacteria on the back of virtually all probiotic supplements and foods, and its benefits to the body are well documentation.


Risks of eating fermented foods?

Fermented foods are very safe, especially if you stick to fermented vegetables. Traditional (which is arguably the best) fermented foods aren’t something that your local supermarket will stock though, so you either have to find a niche outlet, or make them yourself. Making them yourself can be fun, but for most fermented foods it’s often a good idea to get a starter culture to make sure you end up with the right end product, and aren’t eating unwanted bacteria/ toxins they produce.


Fermented foods to try

Fermented foods are healthy, so here are some for you to try!

Yoghurt/ kefir – Real yoghurt is well known for its probiotic properties, and by real yoghurt I don’t mean the sugar laced dairy product that covers most supermarket shelves. Real yoghurt often has a sharp/ sour taste similar to kefir, and this is the one you want. You can easily make it yourself with a yoghurt maker, starter culture and milk, but it will often be somewhere in the supermarkets too. Yoghurt and kefir are possibly the easiest fermented food to introduce to a typical western diet and you can have it for breakfast with some fruit or add it to a smoothie.

Cheeses (particularly blue cheese) – Blue cheese is somewhat of an acquired taste, but the micro-organisms used to make these products heave been shown to have all kinds of benefits including anti-cancer2, probiotic3 and cardio-protective properties4. If blue cheese isn’t your thing, then other fermented cheeses such as cheddar, feta and Gouda have also been shown to have some probiotic benefits5 too, but to a lesser extent.

Natto – I’ll warn you now, natto is like Marmite in that you either love it or hate it (and in all honesty, most Westerners hate it). These fermented soya beans are popular in Asia and are certainly worth a try if you are feeling adventurous, but it’s not something your supermarket will stock, so you will probably have to buy it online.

Kimchi – This is another popular Asian food, but is a little more popular than natto in the Western world. It is essentially fermented cabbage with seasoning, and is usually quite spicy (which can help mask those unique fermented flavours and make it more palatable). It is often used as a side dish, but you can also use it for a relish in some home-made burgers. Kimchi isn’t found in many supermarkets, but it is quite easy to make at home yourself. If you are interested in giving it a go, give this recipe a try.



Fermented foods are something that the Western diet hasn’t really embraced. Yet fermented foods offer us some unique health benefits, and it is for these benefits that people should move out of their comfort zone to try some of these foods.



  1. Barbara Walther. (2013). Menaquinones, Bacteria, and the Food Supply: The Relevance of Dairy and Fermented Food Products to Vitamin K Requirements. Advances in nutrition. 3 (1), 463-473.
  2. Yasuda S. (2010). Effects of highly ripened cheeses on HL-60 human leukemia cells: antiproliferative activity and induction of apoptotic DNA damage. J Dairy Sci. 93 (4), 1393-400.
  3. Kumura H. (2004). Screening of dairy yeast strains for probiotic applications. J Dairy Sci. 87 (12), 4050-6.
  4. Ivan M. Petyaev. (2013). Roquefort Cheese Proteins Inhibit Chlamydia pneumoniae Propagation and LPS-Induced Leukocyte Migration.Scientific World Journal. 4 (1).
  5. G. Gardiner. (1998). Development of a Probiotic Cheddar Cheese Containing Human-Derived Lactobacillus paracasei Strains. Appl Environ Microbiol. 64 (6), 2192-2199.

Image courtesy of thwartedagain.

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