How to improve your gut microbiome
Our gut does more than digest our food, it plays a huge role in our health and disease too
Your gut is so much more than simply a long tube from your mouth to your bum. The digestion of food begins as soon as you eat with enzymes in your saliva breaking down starch, before sliding down your esophagus to your stretchy muscular sack of a stomach. After some churning and acid action the food then passes down to your intestines.
Your upper intestine measures about 6m, intricately and neatly tucked in your insides, and is where 90-95% of the nutrients from food are absorbed. Any leftover bits that can’t be digested then make their way to your lower intestine - the final 1.5m stretch before exiting your rear from your rectum neatly packaged as poo.
The lower intestine doesn’t only act by de-slushing the mushed-up contents drawing water out to form a more solid bowel movement, ready for shipment. It’s also home to the majority of your gut microbiome.
What is the gut microbiome?
Your gut microbiome contains around 100 trillion bacteria, viruses, and fungi - as vast and mysterious as the Milky Way. Not all bacteria and viruses are nasty, unlike anti-bacterial TV adverts and a global pandemic would lead us to believe. In fact, these microbes were here first, far before us humans. We’ve learned to co-evolve together and exist in harmony (for the most part). Together the microbes across our body weigh around 500g and cover us inside and out, not only in our gut. We are just as microbial as we are human, with human to microbial cells at a ratio of about 1:1.
These microbes and the small molecules they produce interact with our cells and our organs, altering the way we respond to drugs, influencing our appetite, our brain function and mood, and performing a myriad of other processes that we still don’t fully understand. The gut truly is a driver of health and disease.
What is a healthy microbiome?
A healthy gut (from mouth to bum) is one that is absent from disease. Some key indicators of a healthy gut (and therefore likely a healthy microbiome too) are:
Bowel movements from three times a day to three times a week - whichever is your ‘normal’
Poo is a brown colour, with no blood
Looks like a smooth sausage, or a sausage with cracks in it
Easy to pass completely with no pain
No uncomfortable digestive symptoms
A healthy gut microbiome is more difficult to assess. Your gut microbiome is a living ecosystem rather like a rainforest. It’s a competitive environment, where some work together and some against others, fighting for the same resources to flourish and grow - yet keeping each other in check too. We wouldn’t want one or a select few plants (or bacteria) to choke out the rest, instead, a healthy inner rainforest is one that is diverse and well-resourced.
We don’t yet know exactly what a healthy microbiome is in terms of specific types of bacteria. Everyone’s gut microbiome is different, and even twins only share about 30% of their gut bacteria. Sorting out the good from the bad isn’t as simple as it might seem. Like humans and our complex character traits, some bacteria appear to be do-gooders in some scenarios, but rabble-raisers in others.
There are though certain types of bacteria that we do know (with varying strength of evidence) to be good for us, called probiotic bacteria. Probiotic bacteria are specific types of bacteria that have a defined health benefit, so really it very much depends on the particular benefit you’re looking for. Some probiotic bacteria are available as supplements, and you can check which types are suitable for which health benefits at www.usprobioticguide.com.
Four key actions for gut health
What to eat
What we eat is the largest modifiable contributor to our gut microbiome, influencing what types of bacteria thrive in our gut, and also what they do too. Our gut bacteria can produce small molecules called metabolites, that can exert beneficial effects on our health from training our immune system to traveling across our blood-brain barrier to our brain.
A Western-style diet that is low in fruits and vegetables, high in less healthy ultra-processed foods, poor quality fats and sugar is linked to more pro-inflammatory bacteria related to type II diabetes, heart disease, and more. As far as the scientific evidence goes, the best diet for our health and our gut bacteria is a Mediterranean dietary pattern.
What is a Mediterranean diet?
Rich in fruits, vegetables, legumes, beans, nuts and seeds, wholegrains, extra virgin olive oil, fish and lean meat.
There are four key dietary factors for our gut microbiome.
Fibre, fibre, fibre (at least 30g per day)
Our gut bacteria feed on plant roughage. It’s like providing them with a feast, they break down fibre and produce beneficial metabolites for our health. We need at least 30g of fibre a day for general health, yet we’re sadly lacking in the UK and US on average meeting only between 15g-18g of fibre a day.
Add in more fibre by:
Swapping refined grains for whole grains, like pasta, rice and flours
Eating beans daily (they contain more fibre than most fruits and veg)
Fill up half your plate with veggies
Keep the skin on fruit and vegetables, like potatoes, carrots and kiwis
Polyphenols
Your gut bacteria like to feed on a group of antioxidants called polyphenols too. They are the colour in fruits and vegetables from the purple in aubergines to the vibrant red in tomatoes. The age-old ‘eat a rainbow’ advice to have a variety of colours in your diet holds true for your gut microbiome too.
Dietary diversity
Often we talk about fibre as if there’s only one type of fibre. When actually, like polyphenols, there are lots of different types of fibres some of which certain gut bacteria like better than others. Having a range of different fibres and polyphenols is thought to be one of the best ways to support your gut microbiome by ensuring that as many bacteria as possible get their preferred ‘dish’ so to speak.
One research study found that people who ate 30 or more different plants a week, had more diverse microbiomes than those who ate 10 different plants a week. It wasn’t the most rigorous research assessment, but it did show that likely having a diverse diet is helpful for our gut. Personally, I don’t find the number 30 here particularly helpful. I prefer to think of diversity more as a general concept rather than getting fixated on counting every smidge of a stray chia seed.
At the supermarket, buy pre-mixed options; multi-variety beans, mixed berries, stirfry mixed bags of veg, mixed grains
Add mixed nuts and seeds as breakfast toppers
Pick a different selection of fruit and veg each week when you’re doing your supermarket shop
Live fermented foods
Fermented foods like kefir, kimchi, yogurt, and sauerkraut are foods that have been acted upon by bacteria and/or yeast, breaking down some of the food’s components to produce a slightly acidic environment that acts as nature’s preservative. They contain a whole host of friendly bacteria and have been shown to increase gut microbial diversity and lower inflammatory markers.
You can find live fermented foods in the refrigerated section (and not the dry-store aisle)
There are many other contributing factors to your gut microbiome like stress and exercise - I’ll cover another day!
That’s it for now! If you have a thought percolating about this, I’d love to hear it - drop me a comment below.
Chat soon, Emily xx
