It’s about the microbiome…
The microbiome is made up of trillions of microorganisms. Some are good guys (probiotics), some are more or less neutral (commensals) and some are bad guys (pathogens).
Every square centimetre of your body, every nook, cranny and crevice has a microbiome, all as unique as you are. Although there may be some cross over, the colonies in your mouth generally have a different mix of microorganisms from those in your eyebrows, your belly button, your feet etc. And research is finding that they are all essential in maintaining our health and wellbeing.
Ideally there needs to be a balance between the probiotics and the commensals to keep the pathogens under control. Mostly the commensals just chug along, giving a bit of a helping hand to the probiotics. But sometimes, if the levels of probiotics dip, or some external factor tips the balance, the commensals can join the dark side and team up with the pathogens. This pushes the microbiome out of balance (known as dysbiosis) which has all sorts of negative effects on our health. The focus here is the microbiome in the gut, which is the one which most of the research (thus far) has been done on.
In the gut
The microbiome in the gut does all kinds of amazing things. It ferments the fibre from the fruit, vegetables, and whole grains that we eat – in fact this is one of the main reasons we need to eat plenty of fruit and vegetables. When it ferments that fibre, it produces a lot of different substances, including short-chain-fatty-acids (SCFAs).
SCFAs are the preferred fuel for the cells that line the gut and keep it healthy. They are also used to make hormones, neurotransmitters, and other chemical messengers which the body uses in communications between the gut, the brain, and the rest of the body (including the immune system). In fact, more neurotransmitters are made in the gut than in the brain. SCFAs also regulate the production of inflammatory chemicals, the absorption of some minerals, our appetite, and glucose and insulin metabolism.
Keeping the microbiome happy requires fibre. Lots and lots of different kinds of fibre.
Different things, both internally and externally, can negatively impact the microbiome. Antibiotics are pretty high on the list because they can kill off a lot of microorganisms, which shifts the balance of good guys, commensals and bad guys. Some food additives also have negative effects on the microbiome, particularly emulsifiers and artificial sweeteners (spoiler alert – artificial sweeteners also mess up your glucose-insulin balance and stimulate inflammation). Stress, lack of sleep, and poor diet can also shift the balance into dysbiosis, away from primarily probiotic and more towards dominance by pathogen.
The impact of inflammation
We now know that inflammation plays a significant role in our mental as well as our physical health. People suffering from depression have higher levels of inflammation throughout their bodies than people who are not depressed. That inflammation may not necessarily be sufficient to cause outright pain, but it is sufficient to impact on mental health. And inflammation is also linked with anxiety, sleep disturbance, and altered appetite.
Quite a few of the pathogens which are found in our gut are linked with increased inflammation. Even at levels that are too low to cause disease, pathogenic bacteria stimulate inflammatory responses, and these are not necessarily confined to the gut.
Can diet help depression?
The simple answer is ‘yes’.
Of course, there is nothing ‘simple’ about diet, particularly when it comes to making changes to it. Nor is there anything simple about depression; why it happens in some people and not in others is still not really understood. It may be the result of inflammation, oxidative stress, genetics, the microbiome, blood sugar balance and insulin response and environmental factors.
The relationship between food and mood is becoming increasingly recognised. ‘Healthy’ eating patterns, like the Mediterranean diet, are associated with better mental health, whilst ‘unhealthy’ eating patterns that are low in fruit, vegetables, whole grains, cold pressed oils, and oily fish, and high in processed foods seem to increase the risk of depression.
Our old friend the microbiome also has an impact on our mental wellbeing. In people suffering depression, the overall diversity of the microbiome is significantly reduced, while the numbers and diversity of pathogens far outweighs that of probiotic microorganisms. And to make matters worse, it seems that some antidepressant medications can actively promote dysbiosis.
Low vitamin D (which most of the UK suffers from, particularly in winter) is a risk factor for depression because, among other things, vitamin D regulates the production of the neurotransmitters serotonin and dopamine. It also regulates inflammatory responses, and influences the microbiome, as well as helping to keep the structure of our gut healthy. Everyone should be taking a 25-microgram vitamin D supplement every day from September to April.
The omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in oily fish and some algal oils, also help to reduce depression. Possibly because the omega-3 oils have powerful anti-inflammatory effects. Or maybe because the omega-3 fats are also involved in maintaining a healthy balance between probiotics, commensals, and pathogens.
If you want to take an omega-3 supplement, look for the one with the highest levels of EPA and DHA you can find. And don’t take it with a hot drink – because hot drinks make the gelatine capsule melt much faster, and you end up with fishy burps – no fun for anyone!
Probiotics for mental health?
Pathogenic species which tend to be more pro-inflammatory have been linked with anxiety and depression whilst probiotic species have been linked with a calmer state of mind. Studies where probiotics have been provided in supplement form often show broadly positive outcomes in reduced levels of stress, anxiety and depression as well as improved overall mood and concentration.
Making changes to daily eating habits by including a broader range of fruit, vegetables and grains can also make a difference. Possibly, because including a broader range of plants in the diet creates a far more favourable gut environment, allowing probiotic microorganisms to thrive, which in turn keeps the pathogens at bay.
The easiest way to get probiotics into our bodies is through taking a supplement. But which supplement? There are so many on the market today that it is difficult to come to a decision. The best way to choose is to do some label reading (I know, how dull!) Look for products with the widest possible range of different varieties. What seems to be most important for the microbiome is balance. Having as wide a variety as possible of different types of probiotic and commensal microorganism within the gut environment. And eating as broad a variety of different types of fibre as possible to keep that microbiome happy.
T C Callis’ articles are very well researched, and always come with a wealth of references. If you are interested in following up anything in the article, don’t hesitate to contact us at Kent Bylines for more information.