While the theory of human intestinal flora being beneficial to gut health isn’t a new concept, we are beginning to understand more about the role of the gut on overall health.
This has seen a rise in the popularity of fermentation and an increase in the availability of fermented foods in stores and supermarkets. But what are fermented foods and what does the science say? Here Nutritionist and Head of Nutrition at Natural Fitness Food Rachel Butcher gives us the low down on fermentation and the evidence behind the proposed health benefits.
What is fermentation?
Fermentation is when bacteria and yeast ‘pre-digest’ food and drink, producing a range of vitamins, beneficial naturally derived acids and other health-promoting compounds or probiotics. Generally, anything that uses microbes to transform simple ingredients comes under the ‘fermented food’ bracket.
Some popular fermented foods including kombucha (fermented tea), kefir (fermented milk, or sugary water if you use water grains), live yogurt and sauerkraut (fermented cabbage) – while these may have increased in popularity over recent years, they have actually been a failsafe in many cultures for thousands of years.
The health benefits
Fermented foods have been associated with a host of potential benefits, including increasing vitamin concentrations (such as folate and vitamin B12), lowering blood pressure, supporting immunity and having a calming effect on anxiety and depression. Fermenting may also lower gluten and lactose content in some foods such as sourdough bread and dairy products.
Probiotic containing fermented foods (live yoghurt, kefir, sauerkraut etc) can influence microbes that colonise our gut though it should be noted that while these can grow, metabolise and interact they rarely permanently colonise, so we need to make the inclusion of these a staple, regular part of our diet to get the benefit.
While I advocate fermented foods and personally believe their inclusion in a varied diet to have a positive impact on health, clinical evidence for the health benefits of most fermented foods is currently limited with the exception of fermented dairy where there is a compelling body evidence for benefits on heart health, bone health, digestion and weight management.
While it may be a new way of preparing food for many, fermenting is super easy to do at home with very little effort. Once you’ve prepared it, you just leave it and allow the microbes to do the hard work for you!
As with dietary fibre, if your current diet contains little to no fermented foods, add these to your diet gradually to avoid GI discomfort and excess gas. You should also speak to your GP first if you have a weakened immune system or are pregnant.
Always make sure your equipment is thoroughly cleaned including the seals and lids. If mould forms during the fermentation process, make sure you discard the batch and start again.
1 white or green cabbage (shredded & washed)
1 tbsp flaked sea salt
2 tsp black peppercorns
½ tsp caraway seeds
- Put the cabbage in a mixing bowl and massage the salt into it with clean hands for 8–10 minutes, or until the cabbage is limp. There should be a pool of liquid left in the bowl. Reserve this to cover the cabbage in the jar.
- Toss the cabbage with the black peppercorns and caraway seeds. Transfer the cabbage and the reserved liquid to a large jar, leaving a gap at the top, and press down well with your fist or a small ladle.
- Place a ramekin or clean jar on top of the cabbage and fill with filtered water or baking beans to weigh it down and keep the cabbage just under the liquid. Cover with the lid securely.
- Leave the cabbage to ferment at room temperature out of direct sunlight, for 4–7 days. The sourness comes from the lactic acid produced during the fermentation process. Loosen, then tighten, the lid briefly each day to allow any gas to escape that has collected as the result of the fermentation process.
- Taste the sauerkraut after 4 days and, if the flavour is as you like it, you can slow the fermentation dramatically by chilling. Alternatively, leave longer to develop the flavour more fully. The sauerkraut should be tangy with a slightly salty cabbage flavour and will become crunchier.
- If the sauerkraut doesn’t taste at all acidic, has an off smell or taste or is discoloured, discard that batch. Once the sauerkraut is ready, it can be stored in the fridge. Leave it for 10-14 days to develop. If kept sealed, it could last for a few months and will just continue to develop a stronger, more tangy flavour. Once started, consume within a couple of weeks.
Try it with cured meats, cheeses or as a sandwich/burger filling
200ml dairy kefir
½ cucumber, grated (patted with a clean tea towel to remove excess water)
2 cloves garlic, crushed
1 tbsp lemon juice
2 tbsp extra virgin olive oil
2 tbsp dill
Pinch of salt & pepper
- Combine all ingredients and serve!
A great accompaniment with falafels or sourdough for a double healthy gut hit.
1 Chinese cabbage (rinsed & chopped)
25g coarse sea salt
6 radishes (coarsely chopped/grated)
2 carrots (coarsely chopped/grated)
2 spring onions (finely shredded)
2 cloves garlic (crushed)
1 tsp ginger (grated)
2 tbsp tamari (or soy sauce)
1 tsp chilli powder
1 tsp paprika
- Put the cabbage and salt in a bowl. Massage the salt into the cabbage firmly
- Pour 500ml of water, over the cabbage and keep it submerged with a weight or plate. Let it soak for 2 hours
- Drain the soaked cabbage, and rinse thoroughly a few times to get rid of the excess salt. Squeeze out any excess water in the cabbage using a clean tea towel and place back in a bowl.
- Add all other ingredients and mix well, before transferring the mixture into a large jar (one with a sealed lid). Using your fist, press down so there’s a layer of juice separating the veg and the air above.
- Seal the lid on and leave at room temperature, out of direct sunlight. Check on your kimchi each day and loosen, then tighten, the lid briefly each day to allow any gas to escape that has collected as the result of the fermentation process.
- After around 3 days (more if it’s cold, less if it’s hot) your kimchi is ready for its first taste. If it doesn’t have an acidic taste, leave for an extra day or two.
- Once it’s reached your preferred flavour, store it in the fridge with the lid sealed. You may notice it fizzing – this is totally normal. Leave it for 2 weeks to allow the flavours to develop.
Delicious served with salads, on crackers or with eggs.
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