Are fermented foods good for your gut?

October 10, 2020

Are fermented food good for your gut microbiome?

Humans share 99% of the same DNA, but the human gut microbiome varies hugely from person to person. Through our research, we have found that even identical twins share only 34% of the same gut microbes.

If we zoom in even closer to look the gut microbiome using new sequencing technologies, it becomes clear that each of us has a unique set of genetic variants (strains) of the microbial species that can be found in each of our guts.

So it turns out that each of us is, in fact, unique microbially. 

Our latest research into the microbiome has shown that there are specific 'good' and 'bad' gut bugs that are linked to 'good' and 'bad' metabolic health. You can find out which ones you have - and get personalized food recommendations to help your ‘good’ microbes thrive - by taking our at-home test.

Your microbiome is unique and has a big effect on your weight, health, and how you respond to food, and eating fermented foods is thought to be a great way to boost your microbiome. In this post, you'll discover:

  • How the food you eat can influence your gut microbiome
  • What fermented foods are
  • How they work
  • Which ones are the best for improving gut health

What are fermented foods?

Fermentation happens when microbes like bacteria and yeast break down food. This may sound like a bad thing, but if it happens in the right way - with the right microbes - then the results can be delicious and nutritious.

Think of the difference between milk that has gone bad and thick, creamy yogurt: they’re both the result of microbes growing in milk, but with very different outcomes.

From bread to beer, cheese to pickles, and more, people have been fermenting their foods for thousands of years, because the fermentation process keeps food edible for longer. 

The microbes used for fermentation can either be purposefully added or arrive spontaneously during the food production process (as you might have witnessed if you are one of the thousands who have tried making your own sourdough starter during lockdown). 

There are hundreds of types of fermented foods from societies around the world. Popular fermented foods include kimchi (spicy fermented vegetables), sauerkraut (fermented cabbage), kombucha (fermented tea), pickled vegetables, live yogurt, kefir (fermented milk), and miso (seasoning made with fermented soybeans). And then there are more unusual examples like Icelandic hákarl (fermented dried shark meat).

Fermented foods change the composition of your microbiome

Scientists from the University of California San Diego have been looking at whether eating fermented foods alters your gut microbiome.

They looked at the diet and microbiome of over six thousand people and found that people who ate fermented plants at least once a week had different microbiome compositions compared with those who didn’t. 

What’s more, they had more conjugated linoleic acid (CLA) in their guts - this is a health-promoting molecule produced by the gut microbes that were associated with eating fermented foods. 

Research has also shown that fermented dairy products like yogurt and kefir can provide additional ‘good’ strains of bacteria, providing your microbiome with additional diversity and giving you potential health benefits, including improved digestion, reduced risk of type 2 diabetes and cardiovascular disease

Why do fermented foods affect our gut health?

Some fermented foods - like yogurt, artisanal cheeses, kimchi, kefir, and sauerkraut - contain living microbes, known as probiotics. Once you’ve eaten them, these bugs can set up home in your gut, increasing the number and diversity of bacteria that make up your microbiome. 

But there are also fermented foods that don’t contain enough living bugs to be considered probiotics. 

When foods are cooked or dried after fermentation, such as sourdough bread or hákarl (in case you were tempted), the microbes are killed by the heat. And only certain types of yogurt having probiotics in them - look out for ‘live’ yogurts in the store to be sure you’re getting a good dose of good bacteria.

Many fermented foods, particularly fermented plant-based foods like kimchi, also contain prebiotics - a type of dietary fiber that acts as food for these ‘good’ gut microbes and encourages their growth. 

What’s more, as fermentation occurs, lots of biologically active molecules (known as post biotics) are released, which also have potential health benefits.

As a result, fermented foods containing live bacteria (probiotics), fiber for them to eat (prebiotics), and the molecules they produce (postbiotics) can provide a triple whammy of benefits for your gut microbiome and overall health. 

Which fermented foods should I eat?

Fermented plants and fermented dairy may change the composition of your microbiome and provide a range of health benefits. There is a huge range of tasty fermented foods you can try, so why not add some diversity to your diet?

Just like us, our gut bacteria have their own food preferences. So if you want to know what foods to eat to have a healthy gut, you need to know which microbes are in there, and how best to feed them. 

Ready to get to know your gut bugs a bit better? Take our at-home test to get personalized recommendations for foods that will reduce dietary inflammation and support your gut health.


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