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Different foods have a specific impact on gut microbiota composition.

The optimal diet for a healthy gut

Diet quantity and quality have a crucial impact on the gut microbiota composition and function.

In the previous step, we reviewed several factors that are thought to impact the gut microbiota. We also discussed that one of the most important factors that could influence the gut microbiota is diet.

Diet type and the gut

Research shows that many aspects of diet can influence gut microbiota. These include:

  • Overall dietary pattern (for example, Western, Traditional, Mediterranean or vegetarian).
  • Specific foods consumed (such as, grains or vegetables).
  • Specific food constituents (for example, fibre, fat or phytochemicals).

Although we are yet to have a clear understanding as to what a healthy gut microbiota should consist of, the common understanding is that a diverse microbiota is a healthy microbiota, and that consuming a wide (diverse) range of healthful foods is important in achieving this.

There are many aspects of diet that we know affect the gut microbiota. In particular, foods with high amount of fibre, such as plant foods - grains, legumes, vegetables, fruit, nuts and seed – support the growth of beneficial bacteria that, in turn, have a beneficial impact on gut and the overall health, including mental health.

In fact, the primary role of gut microbiota is to break down dietary fibre and, in doing so, they release many important molecules that affect health. Without fibre, they can’t do what they’re supposed to do.

Fermented foods

Another food group that has shown a promising effect on gut health is fermented foods. A variety of fermented foods are consumed in many cuisines world-wide, such as yoghurt, kefir, tempeh, kimchi, miso and kvass.

Fermentation is a natural process that occurs when bacteria or yeast break down food components – eg, sugar – to produce metabolites such as lactic acid.

Fermentation is thought to increase the bioavailability and antioxidant activity of foods largely due to variety of benefical metabolites produced in the process, including short chain fatty acids.

Probiotics and prebiotics

Probiotics or prebiotics are popularly referred to in relation to gut health.

Probiotics Probiotics are live microorganisms (bacteria) that are thought to have health benefits. For example Lactobacillus and Bifidobacteria are beneficial bacteria that can aid fermentation. Many fermented foods that are considered probiotics can potentially improve gut immunity and moderate gut-driven inflammation.
Prebiotics Prebiotics are types of fibre digested in the large colon by the gut microbiota.
Prebiotics essentially provide a fuel source for the gut microbiota. Consumption of these is thought to promote the growth of beneficial bacteria and positively impact gut microbiota composition and function.
The best sources of prebiotics include artichokes, beans, leeks, onions, bananas and whole wheat.

Food or supplements?

Although some of the probiotics and prebiotics are available in a purified supplement form, consuming these via food sources would provide a wide variety of naturally occurring substances of nutritional value. Consuming probiotics and prebiotics via food sources will also deliver a range of macro- and micronutrients and reduce any possible side effects.

Other foods that thought to be beneficial to gut health are, as discussed in Step 2.7, fish and seafood that are high in Omega-3 fatty acids and foods high in phytochemicals (eg, polyphenols and carotenoids) such as colourful plant food.

Your task

Reflect on how your own diet may impact your gut health.

Share your thoughts in the discussion below.

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This article is from the free online course:

Food and Mood: Improving Mental Health Through Diet and Nutrition

Deakin University