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Fermentation: Friend or Foe?










Fermented Foods: Friend or Foe?


Since fermented foods and DIY fermentation are hot topics right now, a good question to ask is whether fermentation is a ‘friend or foe?’ I’ll be looking at whether fermentation is in fact a wonder-food that ensures a healthy gut and whether there really is an art to fermentation!

You will already be familiar with some fermented foods and probably eat them on a daily basis. Cheese, bread, yoghurt and alcohol are all fermented and you may have eaten them today. Kombucha, kimchi, sauerkraut and kefir may be less familiar and you may have never eaten them. In fact, they may not seem very appealing to you at first, but our ancestors used to eat lots of fermented foods before we had fridges because they are foods that a balanced body is designed to run on.

I’d like to describe some of the benefits of including fermented food in your diet. But I’ll also include a word of warning…so do read right to the end!


What is fermentation?

If you asked a biologist, they would say fermentation is the anaerobic metabolising of sugars. We understand fermentation as the process of using microorganisms (bacteria, fungi and the enzymes they produce) to convert carbohydrates (sugars) into acid. This acid preserves the food and creates beneficial bacteria and enzymes to make fermented foods a good source of amino acids, vitamins and minerals.


Why should I eat fermented foods?

The most important thing about fermented foods is that they provide beneficial bacteria for a healthy gut. You may be aware of the latest research on the importance of the gastric tract for physical health and even mental wellbeing[1]. Well, fermented foods have been described as the best way to improve gut health because of their large quantities of beneficial bacteria.

The balance of good and bad bacteria in our large intestine is incredibly important. Unfortunately, this balance is adversely affected by poor diets, high intake of sugar, stress and antibiotics. An unhealthy gut impacts negatively on our digestive and immune systems, and an imbalance of bacteria can lead to:

  • food intolerances
  • skin disorders
  • chronic fatigue
  • auto-immune diseases


When should I avoid fermented foods?

Fermented foods can often be high in salt which can be harmful if you are on a low-sodium diet or if you have high blood pressure. They are also high in histamine and should be avoided if you are on a low-histamine diet or if you suspect that you have a histamine intolerance. You can check with me for an assessment of your histamine levels as lots of other foods are also high in histamine, including most aged, cultured, fermented, smoked, and cured foods.

Since much fermented food is probiotic (live organisms), some people recommend incorporating more prebiotics into your diet to promote the growth of microorganisms. These could include onions, asparagus, garlic, legumes, and chickpeas. However, I avoid recommending these foods to everyone because so many people suffer with SIBO (small intestinal bacteria overgrowth) and prebiotics can lead to an increase of IBS symptoms. Please contact me before taking more prebiotics or if you are following a low FODMAP diet to manage IBS symptoms.

Finally, if your symptoms get worse in damp or mouldy conditions, or if they are worse at this time of the year when leaves start to die and fall, then you may find that fermented foods may exasperate your symptoms – please speak to me if you are in any doubt.

How to include fermented foods in your diet

  1. Have a go at fermenting your own food at home! Pick up some organic cabbage and have a go at making sauerkraut. There are many variations, but one simple recipe is to massage 1 tablespoon of salt into 800grams of shredded cabbage and pack it tightly into a fermenting jar once the cabbage starts to release its moisture. Sandor Katz writes some wonderful books, “Wild Fermentation” and “The Art of Fermentation”, and has produced some fantastic YouTube videos.
  2. My favourite kefir recipe is a dairy-free version made with coconut water. Happy Kombucha is a great place to buy your grains and find other good recipes.
  3. Try to eat a variety of fermented foods to ensure a variety of healthy bacteria strains. Dr Natasha Campbell-McBride (a Doctor and Naturopath who specialises in children with autism) even suggests that people should have some sauerkraut with each main meal as it helps to stimulate stomach acid and pancreatic digestive enzyme production!
  4. Finally, enjoy trying some of the healthy fermented foods available and see which ones work for you!:
    1. Yoghurt
    2. Kefir
    3. Kimchi
    4. Kombucha
    5. Miso Soup
    6. Sourdough bread
    7. Sauerkraut

With best wishes,


Emma Maitland-Carew MBANT, Registered Nutritionist in Oxford and Bloxham, Oxfordshire


[1] Surprisingly, the gut produces chemicals such as serotonin that affect our mood and an optimal bacteria balance in the gut actually contributes to positive mental health. A study from McMaster University in Canada reported that anxiety levels in stressed mice was reduced when their gut bacteria was replaced with bacteria from non-stressed mice. You can read more about this study here.


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