Fermented food seems to be ever increasing in popularity! In 2015 I thought I would experiment with making my own fermented foods and started making kimchi, sauerkraut, kombucha, long fermented yoghurt and kefir. It was enjoyable and tasty until my homemade kimchi was too tasty. I thought it would be a good idea to eat a cup full of kimchi with some rice for lunch. OMG there was some fermentation happening in my gut - so much that I had to go home early from work and just lie on the couch in agony! 😩🤔 Needless to say my homemade kimchi days have finished and now I buy delicious NZ made kimchi from my local asian food market. And limit myself to a tablespoon at a time……

What are fermented foods?

Fermented foods are a range of foods in which bacteria naturally (in most but not all cases) present on or in that food are allowed to flourish. For example, sourdough bread is made with a starter culture that is made by mixing flour with water and then allowing the bacteria and yeasts naturally in the flour to grow in conjunction with those present in the air wherever the flour and water mixture is left to stand. This starter culture is then used to make the bread. A similar process is used to produce many foods and drinks for example; wine, beer, yoghurt, sauerkraut, kimchi, kefir, kvass and stinky French cheese. French cheese is particularly fragrant due to bacterial fermentation on the rind of the cheese.

Fermented foods contain millions of bacteria that are thought to have positive gut health benefits when regularly consumed. In the last 10 - 15 years, as genetic sequencing technology has become faster and cheaper, we have learnt which bacteria are present in many traditional fermented foods. For example Korean kimchi contains lots of lactic acid bacteria and fermented milk products contain a variety of lactobacillus bacteria. The bacterial species present in fermented foods can have one or more of the following positive functions:
1. help to create a gut environment unfavourable for harmful bacteria

2. help to break down fibre in the diet

3. may interact with the gut immune system

What impact does eating fermented foods have on our gut function?

Fermented foods have been an integral part of the diet of many cultures for at least centuries and probably millennia. Fermenting vegetables was a way of preserving crops so that during winter, when fresh crops were sparse, people could still enjoy a variety of vegetables, flavours and textures in their diets. Allowing milk to ferment increased its shelf life and produced a range of different textured and flavoured products. Apart from adding a funky flavour to your plate and increasing the shelf life of seasonable produce, we have recently come to understand how regularly consuming fermented foods can be beneficial to gut health. For example, yoghurt that undergoes a long fermentation has lower lactose content because the yoghurt bacterial cultures breakdown the lactose, a milk sugar, into glucose which makes the yoghurt easier to digest for people with lactose intolerance. Kefir, another fermented milk product, is a traditional drink in many eastern european cultures. Kefir can be made with different types of milk and even water. A few months ago a research group in Turkey published the results of a randomised controlled trial of kefir in 45 patients with Crohn’s disease or ulcerative colitis. For the full article click here. In summary, they randomised 25 people to drink 400 mL of kefir twice daily for 4 weeks. The researchers compared abdominal pain, stool frequency and consistency and quality of life at the start and end of the study and analysed stool for changes in lactobacillus bacteria. This small study suggests that regular consumption of kefir probably results in an increased number of lactobacillus bacteria in the gut and that it may help to improve some gut symptoms. These results need to be confirmed in a larger number of people with inflammatory bowel disease (IBD) and with a more realistic volume of kefir (almost a litre of fermented milk everyday is a lot!). But it is one of the first randomised controlled trials published that is investigating how fermented foods might contribute to better gut health.

We are yet to see whether regularly eating fermented foods has a short or long impact on gut health of adults or children with IBD. It is, of course, great to see research being funded and done that can help us to gain a greater understanding on how traditionally important foods and practices impact upon gut health. If you plan to eat fermented foods more regularly I recommend you do so in moderation! Just like when you decide to increase your fibre intake, it is best to do so progressively to give your gut bacteria time to adjust to the new substrates (fuel sources) and to help avoid unwanted side effects. Like most things in nutrition, just because a little is good for you does not mean that more is better.

What other benefits might fermented foods have?

Fermented foods can contribute to your 5+ a day of vegetables and fruit. In my last blog I mentioned polyphenols. Red wine (fermented grapes), kombucha (fermented black or green tea) and beetroot sauerkraut are all fermented foods that contain a range of polyphenols which we think have important health benefits. The addition of a small amount of a fermented food to your meal can make your food taste more interesting and flavourful which is quite important for many people. Fermented foods can also introduce more texture to a dish e.g. tempeh (fermented pressed soya beans).

making Fermented foods at home

Making any fermented food requires some trial and error and can be a labour of love. At home, unlike a highly controlled factory environment, you don’t have a lot of control over the bacteria that grow and flourish in your fermented food. Many cultures have always used naturally occurring bacteria to ferment foods and there is a lot of information online on how to safely do this in your own home.

This month I have been experimenting with making my own sourdough. The process of making sourdough requires a long fermentation period and this process can make sourdough easier to digest. The bacteria present in the sour dough starter starts to breakdown the carbohydrate in wheat flour (fructans and galacto-oligosaccharides). This means that sourdough (made using a traditional process and free from rye) has a lower FODMAP (fermentable carbohydrate) content than wheat flour bread with a short fermentation period such as bread made with yeast.

There are lots of different recipes you can use but I found this one has given me good results. You can make your own sourdough starter by combining a quality flour with water and adding more flour and water each day. After 3 days you will have an active and sour smelling sourdough starter. Once you have a starter prepared and stored in the fridge it then takes 4 days to make a loaf! Like I mentioned, fermented food is a labour of love…. but a little forward planning and some work each day you will end up with a tasty couple of loaves.

Here is a summary of the method I have had success with:

Day 1: take sourdough starter out of fridge, warm up to room temperature and feed

Day 2: combine small amount of active starter with flour and water to make a “leaven”

Day 3: mix leaven with the rest of the flour and water. It’s best to start this when you will be home for 3 - 4 hours e.g. before starting to prepare dinner. Follow folding and resting instructions. Put in fridge over night.

Day 4: BAKE straight from fridge for ~50 mins

Notes: I don’t have, and can’t fit, two dutch ovens in my oven so last time I baked one of the loaves on a hot tray with a small oven proof dish of water on the tray to keep the oven moist. It worked ok.

Happy trial and error if you decide to make some fermented food at home!