Introduction
The bacteria in your gut may be more important than you think. They are so important they are almost considered to be another organ system. There are over 1000 different kinds of bacteria weighing 2kg sitting in your gut which started developing from birth. This whole community of bugs are mostly unique to your body. Think of it as your other fingerprint. Even within specific segments, from the stomach to the intestines, individual colonies of bacteria exist for certain functions. Researchers in science and medicine are just beginning to understand how this can impact everything from your weight to your mood, blood pressure, diabetes and even how you fight infections. This invisible community even influences the nutritional value of food you eat. So how does this happen and what can you do to get things working in your favour?
Effects on the body:
Metabolism:
Gut bacteria produce vitamins important for bodily function. For example, they make the majority of Vitamin K which is required for the clotting function of the blood. They also help to form important amino acids which are the building blocks of larger proteins and help process carbohydrates. In doing so they help to transform food into energy and nutrients for growth. In this way, they also may influence your ability to both put on but also lose weight.
Immune system.
The ‘good’ intestinal bacteria work to limit the effects of the ‘bad’ bacteria which attempt to cause illness and disease. They directly compete, fighting for nutrients and space in the lining of the gut. They release substances which work directly to harm and prevent overgrowth of the bad bacteria. Dysbiosis is the term used to describe when the bad bacteria overgrow, causing a wide variety of symptoms including bloating, abdominal pain, diarrhoea and malabsorption. Bacteria also provide an early warning signalling system to prepare parts of the immune system to fight disease when infections pass through the gut.
Allergy
How you respond to certain foods and the Hay fever you may get in Summer can also be explained by these bacteria. Scientists have compared bacteria between children who have allergies and those who don’t seem to develop problems. It is thought that certain bacteria have the ability to train the immune system to react but also importantly ignore things it shouldn’t fight – such as peanuts, grass pollens and cat hair.
Mental Health:
We have all used our ‘gut instinct’ or had ‘butterflies in the tummy’. When was the last time you were ‘sick to your stomach’?
It seems people have always known there was some link between mental health and the gut. Medically, it seems this was considered even in the 1900’s when patients with depression where sometimes treated with colonic purges or bowel operations in an attempt to remove toxins.
The Gut-Brain Axis
It is now known that there is a two-way communication system between the brain and the gut. This influences everything from memory, learning and your reactions to stress. The vagus nerve was identified as one of the direct connections, and perhaps helps to explain those butterflies as your brain passes on emotions to the stomach.
Researchers have found that chemicals such as serotonin and dopamine, long manipulated by medicines used to treat mental illness, depression and anxiety are linked to the gut. GABA, which is a chemical used to calm the central nervous system is also produced by Lactobacillus rhamnosus, a bacteria used in the fermentation process of some yoghurts. Other strains of this bacteria trigger receptors in the intestine which effect pain perception, in a manner similar to Morphine.
It may also be surprising to you that 50% of irritable bowel syndrome (IBS) patients also meet criteria for mood disorders. Scientists have shown in animals that 2 hours of stress was enough to change the makeup of the gut flora, so it seems that to treat this common problem it is not enough to focus only on the gut, but the mind.
So what can you practically do?
Certainly some of what is already in your gut depends on genetic factors. However, changing gut flora to our advantage has been shown to be helpful both in animals and humans.
3 ways which we can alter the bacteria are through the administration of antibiotics (this can harm the bacteria), prebiotics (foods that promote the growth of beneficial bacteria) and probiotics (beneficial bacteria). Some scientists believe that we might eventually be using good gut bacteria in the same way we currently use anti-anxiety and anti-depression medication. In an experiment where gut bacteria from anxious mice were moved to fearless mice, the personality changed, and the mice became more sociable. Another study found that ladies who regularly consumed beneficial bacteria through yogurt showed altered brain function, both while non-stressed but also during stressful tasks.
Diet
A healthy diet can help promote the ‘good’ bacterial growth. We know people with high vegetable and high fibre diets have significantly different bacterial profiles than those with high fat and sugar diets. Fermentable foods such as miso and sauerkraut increase the level of fermenting bacteria. Non-fermentable fibres such as brown rice, beans, lentils and grains then feed the good bacteria.
Having a varied diet and mixing foods can be helpful, as the broader the range of bacteria you have, the more benefit can be gained. In 3 month old infants we know that the less diverse their gut bacteria, the more likely they are to be sensitized to eggs, milk and peanuts. As you become older, exercise has also been shown to enable bacteria to expand.
Naturally occurring probiotics are contained in food such as yoghurt, kimchi, pickles and kombucha. Probiotics labelled on yogurt are referred to as ‘ABC’ which stands for (Lactobacillus) Acidophilus, Bifidobacterium and (Lactobacillus) Casei. You should choose yoghurts with the most probiotics per serve, aiming for over one billion, sometimes labelled as 1x109 cfu/g. Probiotic supplements have also been shown to be beneficial in some circumstances and more work is being done to measure their effect.
So go healthy, but also smart with the foods you eat to enable the good bacteria to flourish and feed the rest of your body and mind. You may be surprised with the results.