Should I Eat More Fermented Foods?

Article by Claire Johnson


Humans have been fermenting foods for around 10,000 years as a way of preservation and flavour enhancement. However, in more recent decades fermented foods have attracted new attention from the scientific community due to their gut-boosting and health promoting properties.


What are fermented foods?

Fermented foods undergo a process in which microorganisms such as bacteria and yeast break down starches and sugars in foods, creating new compounds and byproducts in the process. Amongst byproducts like acids and alcohols, fermentation also results in the growth of good bacteria that, when consumed, travel through our digestive tract and add diversity to the complex ecosystem of trillions of bacteria, viruses and fungi that we call our gut microbiome. These good bacteria add to the diversity and function of our gut microbiome, which have been found to play important roles in digestion, metabolism, immune function and anti-inflammatory action. In fact, eating fermented foods may increase the number of microbes in our diet by up to 10,000-fold, providing important dietary sources of health-boosting bacteria.  


Emerging research has also started to explore links between these beneficial gut bacteria and the prevention of certain diseases such as cancer, obesity and mental health conditions, although more studies are needed to understand the complex interactions between the microbiome and its human host.


What benefits do fermented foods offer? 

Large amounts of research have found that good bacteria present in fermented foods, such as lactobacillus and bifidobacterium, have beneficial effects on our blood pressure, blood sugar levels, cholesterol levels, metabolism and digestion, as well as containing antioxidant and anti-inflammatory compounds that can protect our cells from oxidative damage, support our immune system and ensure our gut microbiome is balanced and working efficiently. 

The process of fermentation can also remove compounds in foods that can block nutrient absorption, therefore fermented foods may improve nutrient availability and absorption. In addition, fermented foods can improve digestion and reduce some of the negative symptoms associated with food intolerances such as lactose intolerance (EFSA Report, 2011) and other food compounds that can trigger IBS symptoms.

Bacteria present in fermented foods have also been found to play important roles in the synthesis of vitamins such as folate and vitamin B12 which are important for iron absorption, energy, immune function and cardiovascular health.  


Types of fermented foods

Although there are 1000s of fermented foods and beverages across the world, here are some of the most popular products:

Are all fermented foods and beverages healthy?

Whilst most fermented foods contain live beneficial bacteria, different production processes might inactivate live bacteria and reduce potential health benefits. 

Processing, pasteurising and heating are common production methods that may inactivate bacterial cultures in the fermentation process. For example, methods involved in sourdough bread and pasteurised dairy kill bacterial cultures, however live cultures may be added back into dairy products and sourdough bread may still be a better alternative to regular white breads - but not because of any live bacterial cultures. Beer, wine and cider are other examples of fermented beverages whereby the brewing process often kills off live bacterial cultures, which together with the alcohol content, may outweigh potential health benefits and possibly cause damage to our gut microbiome. Additionally, as fermented products increase on our shelves, so might the added ingredients. Products like yoghurt and kombucha often contain added sugars and flavourings, so checking the label can help you identify whether products contain live bacterial cultures and unwanted additives. 


Are fermented foods the same as probiotics?

The terms fermented and probiotics are often used together, which may mislead consumers to believe that all fermented foods have probiotic gut-boosting properties. However, there are key differences between the two. Probiotics always contain live bacterial cultures and have intended health benefits, whereas not all fermented food and beverages do. For this reason the majority of fermented foods are best described as ‘containing live and active cultures’ rather than ‘probiotics.’


Adding fermented foods into your diet

There are no specific guidelines on fermented food intake in the UK. Introducing these foods little and often is a good way to allow your body time to adjust without unwanted side effects such as bloating and gas. 


Top Tips:

  • Introduce side dishes of kimchi or sauerkraut with main meals 

  • Use fermented pastes such as miso paste to flavour your dishes

  • Add fermented vegetables into meals

  • Swap processed animal and vegan meat products for tempeh a few times per week

  • Swap fizzy sodas for kombucha with no added sugar 

  • Have yoghurt or kefir for breakfast


Summary

  • Food fermentation has been around for 1000s of years, however we are only just starting to understand more about their health benefits. 

  • Fermented foods can provide our gut with good bacteria which can positively affect digestion, metabolism, blood pressure, cholesterol levels, heart health and immunity, as well as having antioxidant and anti-inflammatory properties. 

  • Popular fermented products include yoghurt, kefir, kimchi, sauerkraut, miso, tempeh and kombucha

  • Not all fermented products contain live bacteria since productions methods may inactivate bacterial cultures, however these foods may have other health properties

  • Check the label for live bacterial cultures and unwanted additives 

  • Alcoholic beverages such as wine, cider and beer do not usually contain live bacterial cultures and alcohol may negatively affect our gut microbiome. Consume in moderation or opt for low/ non-alcoholic drinks.

  • Introducing fermented foods little and often is a practical way of adding them to your diet.


This blog post was written by Claire Johnson, a Clinical Nutrition Masters student at The University of Roehampton in London. Claire has dedicated the past four years to research and study within female health and hormones, specialising in PCOS, fertility, healthy weight loss and menstrual cycle health. Claire is on a mission to empower and educate women so that they can take their health into their own hands, especially when it comes to hormonal health and commonly under-researched female hormonal conditions. You can find her on Instagram @hormonalhealthcoach.


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