by Ashleigh Feltham,  Accredited Practising Dietitian and Accredited Nutritionist

Your gut microbiome is its own little constantly changing world, and your lifestyle habits affect its weather and ecosystem. An important lifestyle choice is the kind of microbes you invite to live in your gut.

In addition to the positive health benefits of fibre, new research gives insight to the potential roles that fermented foods may have in promoting your optimal gut microbiome.

Your gut microbiome is as unique to you as your fingerprint. Everyone has different numbers and types of microbes that make up their own unique and optimal gut microbiome. Saying this, research strongly suggests that including adequate amounts of dietary fibre is a key component of creating a gut microbiome that supports good health. This is because health-promoting microbes require plant-based foods as a primary fuel source.

Plant-based foods provide prebiotic fibre as well as other fuel components, like polyphenols. Different types of microbes need different types of plant-based foods. This is why aiming to include 30 different plant-based foods a week is a great lifestyle goal to support your health-promoting microbes to thrive.

An adult needs 25-38g of dietary fibre each day. Ensuring at least half of each meal and snack is a source of plant food, you are well on your way to achieving your goals.

A clinical trial selected 36 adults to be randomly allocated to follow either a diet including fermented foods or one high in fibre for ten weeks. The results supported previous research on the importance of including adequate fibre to optimise gut microbiome function and to promote an optimal individual gut microbiome.

In addition, this new research suggests that including fermented foods in your diet is also important. Fermented foods are foods that have been created using microbes, such as sauerkraut, yogurt, kefir, tempeh, tofu, kombucha, and miso. These foods may or may not be classified as probiotic sources. A probiotic source needs to include live microbes that can survive the journey to the part of the gut where they reside and be present in sufficient numbers in order to provide beneficial health benefits to you as the host.

Researchers found that fermented foods increase the diversity of health-promoting microbes in your gut. Just like a garden that is abundant in flower varieties can make it more beautiful, having abundant microbe diversity can make your gut more dynamic, increasing the good health-promoting factors you receive.

Results from this study also found that when fermented foods were included in the diet, there was a reduction of 19 inflammatory markers as well as lower activation of four types of immune cells. If inflammation occurs over a long or chronic period, it can cause diseases such as cancer, metabolic disease, type 2 diabetes, and heart disease as well as obesity. Overactive immune cells can cause autoimmune conditions such as arthritis.

These positive effects of the inclusion of fermented foods were seen to rise with an increase in the amount of fermented foods in the diet. This research is exciting, as it looks at the potential health effects of fermented foods regardless of whether they are considered probiotic sources or not.

Ways you can include both fibre and fermented foods in your day:

1. Top three wholegrain crackers with sauerkraut and tuna.
2. Enjoy a snack of yogurt with berries and cinnamon on top.
3. Make a stir fry using Asian-style vegetables and tofu.
4. Make an egg and salad sandwich and enjoy with a warm cup of miso tea or kombucha.
5. Make a smoothie using chilled kefir, peanut butter and banana with cinnamon.

Take home message:

If you want to optimise the health-promoting potential of a healthy gut microbiome there are several lifestyle factors to add to your daily routine. Two of these are including adequate fibre and fermented foods. The effort you give to support an optimal gut microbiome will return to you in the currency of a healthier mind and body.

References:

1. Wastyk HC, Fragiadakis GK, Perelman D, Dahan D, Merrill BD, Yu FB, Topf M, Gonzalez CG, Van Treuren W, Han S, Robinson JL, Elias JE, Sonnenburg ED, Gardner CD, Sonnenburg JL. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021 Aug 5;184(16):4137-4153.e14. doi: 10.1016/j.cell.2021.06.019. Epub 2021 Jul 12. PMID: 34256014; PMCID: PMC9020749.
2. What is Food Fermentation? WebMD.
3. Fermented-food diet increases microbiome diversity, decreases inflammatory proteins, study finds. Stanford Medicine News Centre.