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When we think about optimising our health, our gut is probably not the first bodily system we may think of. And yet optimal health is almost impossible if we don't consider taking care of our gut which is home to our microbiome.

We used to say, ‘you are what you eat,’ and an update on that has been ‘you are what you digest and absorb’. But in his book “The Clever Guts Diet” Dr Michael Mosley proposes “you are what you feed your microbiome.” He says that every time he puts something in his mouth, he considers what it will do not just to his body, but also to his biome. Every food decision you make decides the fate of countless billions living in your colon. It’s quite a responsibility!

So why is this so important?

It is now known that the human gastrointestinal tract is home to more than 1000 species of microbial organisms, mostly bacteria, but also yeast and viruses. These organisms are collectively known as the microbiome, and they far outnumber the human cells by about ten times. Alongside the large number of cells, the microbiome itself can weight from 5-7 pounds!

A variety of factors influence the development and maintenance of a ‘healthy microbiome’, which is important given that our relationship with our microbiome lasts our lifetime!

Whilst the entire pool of possible members of the microbiota is large with over 1000 species, a much smaller number of up to 170 species can be found to predominate in any given individual. As in any ecological system a higher diversity is associated with greater health and the gut is no different. We can think of our microbiome as a complex rainforest with thousands of competing and co-existing species, living in overall balance.

A high diversity of GI organisms has been associated with states of relatively good health while low diversity has been associated with states of disease or chronic dysfunction including Irritable Bowel Syndrome, Inflammatory Bowel Disease, allergies and obesity.

The microbiome is a dynamic entity, influenced by several factors, including birth delivery, genetics, diet, metabolism, age, geography, antibiotic treatment, and stress. The microbiota can be a good representation of the environmental history of the individual and can contribute to individual differences in not only risk of illness, but also disease course and treatment response.

So why are these microbes important?

  • They manufacture some of our B vitamins which are important for mental health and energy.

  • They also manufacture vitamin K which is essential for blood clotting.

  • They play a role in the harvesting of calories from our food and can influence weight gain.

  • They ferment indigestible fibres from vegetables and release metabolites called short-chain fatty acids which provide fuel for the cells in the colon.

  • They interact with our immune system and nervous system.

More traditional culinary habits may have included slow-cooked stews and casseroles, inclusion of organ meats, regularly eating a wide range of vegetables, including green vegetables, home-made stocks, drinking live yogurts or fermented foods and eating slow-produced quality breads such as sourdough bread and smelly cheeses. Instead, our modern, Western diet is focused around fast food consisting of refined carbohydrates, sugar, trans-fats, artificial sweeteners, caffeine and alcohol which are all damaging to our microbiome. On top of this, antibiotics and anti-bacterial wipes are another assault on the health and variety of our microbial populations.

So now we understand how important it is to eat a large variety of different foods. Ask yourself, how many different plants have you eaten this week? If it is only a repetitive handful, then the diversity in your microbial species may be reflecting the same limitations.

Take this a sign to liven up your plate, try a new food each mealtime! The more diverse your intake of plants and flora, not forgetting herbs and spices, the better your health and the more stable your weight. A rainbow on our plate can contribute to a diverse and balanced microbiome.

So, what can we eat to improve our diversity?

Of all the factors that can affect and influence or gut microbiome, a long-term diet appears to have the largest effect to date. Aim for several cups of plants per day, with at least five coming from vegetables and two from fruit. Ideally, we want to be aiming for 20-30 different varieties of fruit, vegetables and herbs each week. This variety doesn’t only provide colour and phytonutrients, but it also provides the fibre which can help feed our gut bacteria.

Prebiotic Foods

Prebiotic foods contain materials which cannot be broken down in the upper digestive system, but they provide food and encourage the growth of beneficial bacteria in the colon. Prebiotic foods include apples, bananas, asparagus, leeks, onions, garlic, inulin, Jerusalem artichokes and cold potatoes. Try to think of prebiotic foods as fertiliser for our beneficial bacteria.

Probiotic Foods

Probiotic foods are those which contain live bacteria such as yogurt and kefir or other fermented milks. However, its important to be mindful of the sugar content in some of the mainstream ‘probiotic drinks.’ Other fermented foods include live miso soup and tempeh.

Fermented Foods

Pickled vegetables including sauerkraut are other common fermented foods. Make sure to buy these products fresh and ensure they contain living bacteria.

Apple cider vinegar is another example of a fermented food and can be used as part of a vinaigrette on salads. Some interesting research has shown that it may also be beneficial for blood sugar levels and cholesterol.

It’s important to note that its not just our diet that can impact our microbiome, but our lifestyle too.

Intermittent fasting

Intermittent fasting has been shown to improve the abundance and diversity of gut microbiota. If you can, try intermittent fasting by extending the hours of your gap between meals.


Recently, it has been proposed that physical exercise is able to modify gut microbiota, and thus this could be another factor by which exercise promotes well-being.

Stress and lack of sleep

Elevated and long-term stress and lack of sleep can lead to an unhealthy microbiome.

Mindful Eating

Eating slowly and mindfully and chewing abundantly can optimise digestive function.

So, in summary, keep your plate colourful, keep moving, breathe deeply and sleep long for a healthy microbiome.

Image: Anna Pelzer

Source: Unsplash

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