Sauerkraut variety preserving jars. Homemade red cabbage beetroot kraut, turmeric yellow kraut, marinated cauliflower, carrots and radish pickles Fermented food

The A-Z of fermented foods

Fermentation is the process in which microorganisms such as bacteria, yeast or fungi convert organic compounds – usually carbohydrates such as sugars and starch – into alcohol or acids.

The role of fermentation is varied, it was originally used to preserve foods, it makes food more digestible, changes the taste of foods and decreases cooking time. The bacteria involved in fermentation produce micronutrients, are a source of good bacteria’ for the gut and can reduce anti-nutrients.

Fermented foods such as kimchi, sauerkraut, kefir and kombucha have recently become popular in health conscious population due to their probiotic or ‘good bacteria’ content. These probiotics have been shown to improve intestinal tract health, enhance the immune system, reduce symptoms of lactose intolerance, potentially reduce prevalence of allergies and reduce risk of certain cancer. They may also play are role in improving our mental health.

So what are they and should I use them?

  • Kombucha is a drink traditionally made by fermenting sweetened tea with a symbiotic culture of bacteria and yeast, commonly referred to as a ‘scoby.’ Its lower sugar content makes it a good alternative to a sugary drink.
  • Kefir is a fermented milk drink made with kefir ‘grains’ – a fermentation starter made of yeast and bacteria. Traditionally, kefir was used to treat gastrointestinal problems, hypertension and allergies.
  • Kimchi is a traditional Korean side dish, made from salted and fermented vegetables, most commonly cabbage with a variety of seasonings.
  • Sauerkraut is finely cut cabbage that has been fermented by various lactic acid bacteria giving it a distinctive sour flavour.
  • Miso is a traditional Japanese seasoning, a thick paste used in sauces, spreads, picking and of course in miso soup,  produced by fermenting souybeans with salt and koji (a fungus) and sometimes other ingredients.

In the context of a healthy balanced diet, including some fermented foods for flavour, variety and the potential gut benefits would be a welcome addition. However, be careful not rely on these foods as a cure-all.


Parvez, S., Malika, M.A., Ah Kang, S., Kim, H.Y. (2006). Probiotics and their fermented food products are beneficial for health, J Appl Microbiol, 100(6), 1171-1185.
Vina, I., Semjonovs, P., Linde, R., Denina, I. (2014). Current evidence on physiological activity and expected health effects of kombucha fermented beverage, J Med Food, 17(2), 179-188.
Leite, A.M., Miguel, M.A., Peixoto, R.S., Rosado, A.S, et al. (2013). Microbiological, technological and therapeutic properties of kefir: a natural probiotic beverage, Braz J Microbiol, 44(2), 341-249.