Making sense of the microbiome

If you’ve been hanging out on social media lately, or even just on earth, then you’ve probably heard the terms ‘microbiota’ and ‘microbiome’ being thrown around. Perhaps you’ve even wondered what they mean? Well hold onto your phones, because HeadUp's about to break things down!

The human microbiota refers to the millions of tiny organisms or microbes living on and in our bodies, including bacteria, archaea, fungi and viruses. The human microbiome refers to their combined genetic material. So, microbiota = the microbes themselves. Microbiome = their genes.

You might be fascinated (or disgusted) to know that we are well and truly outnumbered by microbes. There are 22,000 genes in the human genome and millions in the microbiome. In fact 90% of the cells in our body are considered ‘non-human’. Makes you wonder what it means to be 'human'... 

We’re pretty keen to learn more about our tiny residents so there’s a whole project dedicated to them: The Human Microbiome Project. But microbial research isn’t new. It started back in 1680, when a man named Antonie van Leewenhoek compared poo from healthy people to poo from sick people and found striking differences in microbe population.

What IS new is our ability to use powerful molecular techniques and technology to understand how the microbiome affects different processes of the human body. In other words, modern-day microbe researchers still spend a lot of time playing with poo, but they use way more expensive equipment.

 Modern scientific technology allows scientists to get reallllyy up close to poo. So close, they can practically saddle up and ride microbes like cowboys. Image via: https://bit.ly/2JEARcW

Modern scientific technology allows scientists to get reallllyy up close to poo. So close, they can practically saddle up and ride microbes like cowboys. Image via: https://bit.ly/2JEARcW

Where do they live?

Microbes are found everywhere, but mainly in three places: your skin, mouth, and digestive tract (gut). There are 2-3 times more bacteria in your body than any other microbe, and they love hanging out in the gut. They specifically like the intestines. Scientists think there are anywhere from 500-1000 species of bacteria in the human gut, but one third of them haven’t been identified. So there’s still a lot we don’t know.

What we do know is that humans are about 99.9% identical to one another when you compare their genes. But they can be 80-90% different from one another when you compare their gut microbiomes.

Why is this relevant and what does it mean? Basically, if doctors can base treatments and medicine on individual patient data (AKA their microbiome), then the future of healthcare is bright, because we’re looking at personalised treatments for each patient. 

 Artist's impression of bacteria hanging out in the large intestine. Image via: https://bit.ly/2HrSUhv

Artist's impression of bacteria hanging out in the large intestine. Image via: https://bit.ly/2HrSUhv

You are what you eat. Literally.

Research suggests your gut microbiome is influenced by:

A diet very high in fat, sugar, and processed foods is said to push the overall balance of bacteria in your gut from ‘good’ to ‘bad’. This imbalance is called dysbiosis. Another thing that affects your microbiome is a lack of variety in your diet. Both dysbiosis and low bacteria diversity have been linked to health problems like insulin resistance and weight gain.

The idea is to try to avoid dysbiosis – and this might be best achieved by eating a variety of healthy foods. Studies have shown that Japanese people have a more diverse gut microbiome than most, so their diet is considered to be gold-standard. It is rich in fermented food (full of probiotics, which are good bacteria), vegetables, and seasonal variety.

 Lactobacillus acidophilus is a 'goodie': a bacteria you want more of. Image via: https://bit.ly/2Jmxx2K

Lactobacillus acidophilus is a 'goodie': a bacteria you want more of. Image via: https://bit.ly/2Jmxx2K

Some medical professionals recommend we seek inspiration from the Japanese and boost our levels of good bacteria by eating probiotic-rich foods. Examples include yoghurt, sauerkraut, kefir, and kimchi.

But if you’re tempted to hit up your local chemist for some probiotic supplements: hold up! There’s a couple of things to consider. Firstly, many probiotic supplements deliver a lot of the same thing: the same type of bacteria over and over, as opposed to different types - and as we mentioned above, we need diversity in our gut bacteria. Secondly, probiotics alone, cannot work their magic.

This is where prebiotics come in. Prebiotics are dietary fibres found in carb-based foods that humans can’t digest. This may seem weird, but prebiotics aren’t meant to feed YOU: their job is to feed and maintain the good bacteria. You can find them in legumes, onions, cabbage, garlic, asparagus, oats and beans. Basically, stocking up on probiotics without prebiotics is essentially useless. Expensively useless.

 You can thank these guys for diarrhoea. Clostridium difficile is a bacteria that's harmless in tiny numbers, but when good bacteria are gone, they take over and put your gut microbiome out of whack. Image via: https://bit.ly/2aZ7jkS

You can thank these guys for diarrhoea. Clostridium difficile is a bacteria that's harmless in tiny numbers, but when good bacteria are gone, they take over and put your gut microbiome out of whack. Image via: https://bit.ly/2aZ7jkS

It's looking like the microbiome is linked to EVERYTHING

1. Brain health. Scientists have started to link healthy gut function to normal nervous system function. In one study researchers put ‘good’ bacteria into a mouse gut - and found that it stopped symptoms of anxiety. And in another study, gut microbe samples from people with major depressive disorder were transferred to rats. The rats went on to show behavioural changes related to depression.

2. Heart health. Gut microbes release substances called 'metabolites'. One type of metabolite they produce - trimethylamine - is linked to atherosclerosis, which is a cardiovascular disease. We still don’t know exactly which bacteria produce trimethylamine, but when we do, doctors could potentially manage cardiovascular diseases by targeting a tiny number of gut bacteria types with very specific antibodies.

3. Digestion and nutrition. It’s believed that the genes of our gut microbiome help us digest foods that humans, if left to their own DNA, would not be able to. Because we have the microbiome to help us though, we can extract energy from a broader range of foods.

4. Obesity. It’s been shown that transfer of faecal matter - poo - from an obese human can lead to weight gain in a recipient mouse. One day, when we know more, researchers hope to target specific microbes as a treatment for obesity.

 Scientists are painting a clearer picture of how gut bacteria interact with the mind. Illustration by Benjamin Arthur for National Public Radio: https://n.pr/2Lvb04r

Scientists are painting a clearer picture of how gut bacteria interact with the mind. Illustration by Benjamin Arthur for National Public Radio: https://n.pr/2Lvb04r

Take-home message

Microbiome research has, quite simply, exploded. And it’s showing no signs of slowing down. It’s exciting. But we need to remember that it’s still in its early stages. So, while it seems that a healthy gut can help people with anything from depression to household chores, we still can’t say for sure that it actually does help, and how. Basically, hold onto your meds.

We will say this: just because something hasn’t been thoroughly proven, doesn’t mean it’s not true. We've seen some very promising results so far. It’s just that we need more experiments to be done in humans before the discoveries are integrated into medical care.

At the end of the day, the current advice for ‘building’ a healthy gut is the same advice we’d give to anyone wanting to be healthier. Eating lots of different types of vegetables, getting enough fibre, and limiting processed foods might be the key to a healthy gut, but we know, based on actual data we’ve seen in our lab, it IS the key to a healthy body.

Understanding all the bits and pieces of the human body can be difficult and overwhelming. So, at HeadUp, we’ve made it our mission to unravel the science as clearly, openly and honestly for you as possible. That way, you can make the best evidence-based decisions for your health.

 

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*Please note: header image via University of Massachusetts: https://bit.ly/2Lvsga3