If you listen to the health chatter on the TV news, in magazines and on the internet you will have heard about the importance of gut bacteria to health. Gut bacteria seem to be responsible for everything from gastrointestinal health to mental health to reducing high blood pressure. Modern “western” diets which are typically low in fibre and high in processed foods are being linked to the rise of obesity and Type 2 diabetes because of the deleterious effect they have on gut bacteria.
I have been researching and thinking about the microbes in my gut for over a year. I started to read the research, then switched to a mostly plant based diet, deliberately increased the amounts of probiotic and prebiotic foods that I am eating and generally trying to be nice to my gut bugs.
This time, I have put my body (and dignity) forward in the interests of science and bought a uBiome Test kit to check out what is actually living in my gut. It took 3 weeks to get the package from the US and then another 6 weeks to get the results.
The results are very comprehensive and frankly a bit of science-jargon-babble. I am a scientist and I found the data a bit overwhelming and not easy to interpret. I think they could provide a bit more help in unraveling the numbers.
I have become a bit obsessed with the amazing microbiome that is present in our gut. The billions of microorganisms that live inside us and have the potential to do so much good if we look after them.
Gut Microbes and Health.
More and more research shows that this microbiome is essential to our physical and mental health and many of the health problems facing those in industrialized economies could be solved by paying closer attention to what bugs are in your gut.
When your bug population get out of balance (dysbiosis) your whole body is in trouble.
The gut biome has been linked to
Synthesis of vitamins and amino acids in the gut
Digestion of “non-digestible” carbohydrates which therefore affects the amount of energy that is released from some foods
Protection from “bad” bacteria
Irritable bowel syndrome and inflammatory bowel disease
Obesity and Type 2 Diabetes
Eczema and asthma
Most studies of overweight and obese people show a dysbiosis characterised by a lower diversity.
Translation: Obese people have an imbalance of microorganisms with not enough variety present
It’s much better to have a good variety of microorganisms in your gut because:
The association between reduced diversity and disease indicates that a species-rich gut ecosystem is more robust against environmental influences, as functionally related microbes in an intact ecosystem can compensate for the function of other missing species. Consequently, diversity seems to be a generally good indicator of a “healthy gut.”
Translation: Having lots of different species of bacteria makes your body better able to withstand challenges because what one bug can’t do another type can. They can cover all bases by working together.
Fibre is the answer!
So how do you get a good mix of bugs in your gut? The key is consuming a goodly amount of dietary fibre and reducing the amounts of highly processed foods that we eat.
The idea is that we need to feed our gut bugs. Highly processed foods are easily digested and absorbed and don’t make it to the large intestine where most of the bug action is happening. By eating foods high in undigestable fibre, we give the bugs a meal as well.
How much is enough? Australia’s CSIRO recommend between 25 – 35 g per day. Having said that; too much fibre can reduce the diversity of your microbiome and if you suddenly change from a low fibre diet to a high fibre diet you can suffer from abdominal discomfort and flatulence. You should spread fibre consumption throughout the day and drink plenty of water to keep it moving through your intestines.
Types of fibre
There are different types of fibre which have different properties. The main types are insoluble, soluble and resistant starch.
Insoluble fibre found in whole grains, legumes, vegetables, nuts and seeds provides bulk and can help control blood sugar levels.
Soluble fibre found in legumes, veggies and fruits give the bugs something to eat so they stay happy
Resistant starch, which is found in cooked, cooled and reheated rice, potato and pasta, as well has whole grains, legumes and under ripe bananas. Resistant starch increases the amounts of butyrate in the gut. Butyrate, a byproduct of microbial metabolism, is important in keeping the gut walls healthy as well as keeping bad bacteria at bay.
What are probiotics and prebiotics?
Probiotics are foods or supplements that contain living organisms such as yogurt and other fermented foods. Prebiotics on the other hand are foods that help the microorganisms in your body thrive.
A good analogy is that if you think of your gut as a garden, the probiotics are the seeds and the prebiotics the fertiliser.
Some chemicals and medications will damage your gut bugs.
Antibiotics kill bacteria. That’s their job, so they kill the bacteria in your gut too. You may need to take some extra special care of your gut bugs after antibiotics. There is some evidence that the appendix acts a reservoir for the microbiome and in time will help repopulate the gut with good bugs.
Emulsifiers are added to food to make oily and watery components stay mixed together. If you mix oil and vinegar together, they will after time, separate into layers unless you add an emulsifier. Some artificial emulsifiers have been linked to damaging the gut microbiome because they lead to a thinning of the mucous layer in the gut which in turn leads to leaky gut syndrome. This causes inflammation in many areas of the body. The answer? Prepare your own food from scratch as often as possible and avoid things your grandparents would not have considered as food. Be wary of foods with lots of numbers in the ingredient list and not many recognisable as food.
Omnivore vs vegan?
There does not seem to be much evidence that a well balanced omnivorous diet is any better or worse than a vegan diet. (see The BMJ article referred to below) Michael Mosley and others wholeheartedly recommend a “Mediterranean diet“. This type of diet is mostly plant based but does include meat, eggs, some dairy, healthy oils and nuts.
Further reading on gut microbes and health.
This post is only a very short summary of the growing volume of information available. Here are just a few of the articles you could read to if you want to know more.
What you eat controls the bacteria in your gut. The bacteria in your gut controls your mood and can now be linked directly to symptoms of anxiety and depression
We all know that eating a healthy diet is really important in keeping yourself physically fit but mounting medical research is showing that it could also be the key to good mental health.
Recent studies have shown that there is a direct link from a Western diet – i.e. one that is high in processed foods, sugar, soft drinks (either with or without sugar) to poor mental health.
Conversely, a “Mediterranean” diet rich in vegetables, fruit, whole grains, legumes, nuts, some dairy and healthy oils has been found to be protective and even curative for some mental health conditions. Adding pre-biotics in the form of fermented foods helps even more.
Our gut is inhabited by a whole host of bacteria – “good bacteria”. This is our gut biome or gut microflora. There are in fact more bacterial cells in your gut than cells in your entire body! (They are much smaller than our own cells so they don’t take up much room!) These microbes produce chemicals that affect our mood and act directly on our brain. When we eat a diet high in refined foods, we leave nothing for the bacteria that live in our lower gut to eat. They starve and die off. The diversity of our gut microflora is reduced and hence the good mood chemicals are not around to keep us mentally healthy.
So if you are feeling a bit low or anxious, diet may be a good and relatively easy starting point. First steps are to cut the CRAP
If you want to know more have a look at the links below.
Firstly, a great podcast that gives some of the science and places to get more information