Gut thinking
Depressive disorder is one of the leading causes of disability worldwide. It is estimated that every one in five people will probably suffer from depressive moods in one stage of their lifespan.
We know that a poor diet negatively impacts our physical health but it’s not only our physical health that is affected – the effects on our mental health can also be devastating.
In this blog I will talk about the different mechanisms by which an unbalanced gut microbiome has consequences for our mood.
Did you know that studies on animals show that in the absence of gut bacteria they are much more reactive to stress. This has led to some scientists to call our gut bacteria ‘our brain’s peacekeepers’. Happy gut bugs work together to reduce inflammation, which is a contributing factor to depression.
1 - THE VAGUS NERVE – THE GUT BRAIN AXIS
The gut and the brain are directly connected by the vagus nerve.
This nerve is made up of fibres that connect the brain to the cells of the gut lining in our intestinal tract.
We have known for a long time that the brain communicates with the gut but we now realise that the messages sent from the gut to the brain are much stronger than the messages from the brain down. This is really great news as this means that we might be able to influence our moods with what we eat.
When we are having a meal and the gut brain axis mechanism works properly :
The digestive tract will send messages though the vagus nerve to the brain to secrete digestive substances in order to support digestion.
The gut will also alert the brain to produce anti-inflammatory substances in response to digestive inflammation.
The messages to the brain will also ensure that the permeability in the gut lining is under control.
What we also know is that anything your brain perceives as stress will shut down the vagus nerve and this crutial gut brain connection. If due to stress inflammation is not supressed the gut bacteria will suffer.
Moreover if the gut lining becomes too porous this will lead to what is called gut hyper -permeability ( commonly known as a leaky gut). This will contribute to a localised inflammation to become systemic in the body affecting brain function and mood.
Chronic low grade inflammation occur more often in disorders such as anxiety and depression.
2- INFLAMMATION AND BUTYRATE
When we have a diverse microbiome we have more bacteria available to produce butyrate (A short chain fatty acid). One of the function of Butyrate is to make the gut lining less porous. Good gut integrity will in turn prevent inflammatory metabolites produced by some microbes to reach the brain and modify our mood,
A healthy gut lining seems to be protective against the low grade chronic inflammation associated with depression.
3 – SEROTONIN AND GABA
Our gut bacteria produce and regulate Serotonin- aka our happy hormone- and also GABA.
It is estimated that up to 95 % of our serotonin is produced in our gut . Having enough serotonin helps to regulate our mood and low levels have been linked to depression.
The mechanism is that when our bacteria produce enough short chain fatty acids such as butyrate, butyrate will interact with the cells responsible for the production of serotonin leading to a higher amount of serotonin beeing produced.
GABA also play a role in improving mood, it is more of a relaxing hormone. Several strain of probiotics bacteria such as Bifidobacterium lactobacillus can actually make GABA.
SOME CONSIDERATIONS :
The more balanced your gut is with good intestinal integrity, good amount and diversity of bacteria and lower inflammation, the better your mood and lower your risk to suffer from depression.
However, current research on gut microbiota and mood disorders is still at its early stage. Growing evidence shows changed gut microbiota in patients with mood disorders, which may play an important role in disease pathology. The cause-effect relationship is still a question mark.
No consensus has currently emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression.
It is more than likely that we will know more in the years to come and that this is a promising area of study.
In the meantime what you can do to protect your mental health :
Look after your gut with natural probiotics such as Kefir sauerkraut.
Fed your gut bacteria with prebiotic foods such as fruits and vegetables, nuts and seeds legumes resistant starch
To increase variety aim to add 2 different type of fruits vegetables to your diet weekly.
Eat a varied diet and go for 30 plant food per week. Keep is bright and coloured.
Eat foods that contain different types of natural substances able to contribute to the generation of Serotonin and GBA, facilitated by your gut bacteria).GABA: Highest in raw spinach potatoes followed by sweet potato, kale broccoli mushroom and chestnut.Serotonin : Most prevalent in green banana peel! Pepper paprika and hazelnut.
In 2017 Head to the Med produced a very promising gold standard randomized control study known as the SMILE trial. This was the first study of its kind to investigate the questions ‘if I improve my diet, will my mood improve?’
The researchers put patients with severed or moderate depression on a whole food Mediterranean diet : It was full of a wide variety of diverse and minimally processed foods such as oily fish, olive oil, colourful fruit and vegetables and wholegrains.
Results:
“At the end of the trial, a third of those in the dietary support group met criteria for remission of major depression, compared to 8 percent of those in the social support group.”
These results were closely related to the extent of dietary change.