By Meleni Aldridge, executive coordinator, ANH-Intl; nutritional & cPNI practitioner

Would it surprise you to find out that mood management is one of the prime functions, not only of our brains and neurotransmitters, but also of the non-human microorganisms that inhabit our gut? During our ancestral past, it appears we used to have around 160 different species of microbes (bacteria, fungi, viruses, worms and parasites) resident in our gut. Today, those of us living in the developed world have reached crisis point with our microbial diversity. In looking at the diversity of indigenous populations, we have a benchmark to see that we have lost keystone species that are essential butyrate producers. Butyrate is a short chain fatty acid with many varied effects, but none more so than being a potent regulator of gene expression.

It’s not just chronic disease spiralling out of control, mental health issues are now commonplace and continuing to rise at a swift pace. Mainstream medicine is still focused on disease management strategies, like drug therapy, for symptoms. But what about strategies that address the cause(s) of what ails us and resolves the health challenge at its core?

The subject of the gut-brain connection for mood modification was one of the key scientific streams presented at this year’s Australasian Society of Lifestyle Medicine’s annual conference in Sydney last weekend. For your benefit, I’ve pulled out some fascinating insights that reflect some of the most recent advances in the field from a range of eminent researchers and clinicians who presented at the conference.

Our internal ecosystem

We are an entire ecosystem unto ourselves and just like the coral reefs or the rainforests, we need to maintain the delicate balance for the system to flourish. Allow disruption to creep in and the system fails. Our relationship with the trillion plus microbes that inhabit our healthy guts is wholly mutualistic (not just commensal). We must live in harmonious cohabitation to keep our gut microbiota in its naturally diverse, complex and intelligent system within us if we are to optimise our physical and emotional health, as well as our resilience.

Our microbiome is a unique fingerprint of each of us – even in identical twins. What and how we eat is one of the most important determinants of the diversity of our microbiota. Not just because our food provides nutrition, but because of the metabolites produced by the microbiota that then act as signalling molecules for the multitude of metabolic and related processes that are needed to keep us well. Knowing this, how can we not question whether our diseases of civilisation are just symptoms of our microbiome being out of ecological balance?

Depression – a symptom of a disordered gut?

An altered ecosystem can increase the risk of depression because stress impacts the microbiota negatively. We now know that that relationship is bi-directional. So, the way we eat, rest, move and feel emotionally has a direct impact on our gut microbiome creating a suite of negative effects – depression being one of them. How? Because the immune, hormonal and nervous systems act as the language translators between the intestinal mucosa (mucous lining), the microbiota (the microorganisms themselves) and the brain. Hence, a properly functioning microbiome can modulate the stress response and help us to be more stress tolerant and resilient.

New evidence suggests that depression may also be transmissible. A study in 2016 showed that faecal transplants from clinically depressed human patients given to laboratory rats, created depressed rats. How this may affect babies born to depressed mothers is yet to be seen, but this finding shouldn’t be ignored.

Known mood modifying mechanisms involving the gut microbiome are as follows:

  • An excess production of internal toxins (lipopolysaccharides - LPS) created from the outer shells of gram-negative bacteria without sufficient species diversity to offset the effects. The overuse of NSAIDs e.g. ibuprofen, increases LPS concentration. As does binge drinking which creates a high level of internal toxins in the blood stream detectable for up to 5 hours after the drinking session.
  • Lower than normal levels of butyrate production, which can be made by 30-40% of the bacteria in healthy people. Amongst its many effects, butyrate enhances gut integrity and can also prevent depression from occurring, but only when more is made than is needed by the colon cells. Eating a standard Western diet (low in fibre, prebiotics and resistant starches, but high in meat and unhealthy/refined polyunsaturated and saturated fats e.g. trans fats) will not provide this protection.
  • Production of neurotransmitters e.g. serotonin, aka the ‘happy hormone’ (90% is produced in the gut) and disruption of the tryptophan pathway in the brain. This also creates brain inflammation because the blood-brain barrier is compromised, which can induce depressive-like behaviour. Dopamine, noradrenaline and serotonin must be balanced to maintain an even, happy mood.
  • B vitamins (involved in creating neurotransmitters) – produced by the microbiota and colon cells, but only if the right foods are eaten. Again, the typical Western diet will not provide this.
  • Insulin resistance from poor blood sugar balance.
  • Intestinal permeability – lack of anti-inflammatory species can create a microbiota that increases gut permeability

DIY fixes you can start today

Given that a build-up of toxins in the gut, and the body beyond, from an excess of LPS in circulation is at the heart of depression or depressive-like behaviour, the following are some simple, yet effective, DIY fixes:

  • Change to a high fibre diet (30 grams plus a day for adults, comprised of a variety of soluble and insoluble sources) and eat fibre with every meal to prevent metabolic endotoxaemia – the internal toxicity created by excess LPS
  • Lower dietary fat intake – sat fats particularly increase uptake of endotoxaemia
  • Eat more oily fish (e.g. mackerel, sardines, salmon) and take an omega 3 (DHA/EPA) supplement as fish oil has been shown to decrease LPS absorption. Algal DHA/EPA supplements are now available for vegetarians and vegans.
  • Look at labels and avoid eating highly processed and ready-to-eat foods because they often contain high levels of dietary emulsifiers which can damage the integrity of your intestinal wall
  • Avoid binge drinking (2ml vodka / kg body weight – 65kg person = 4.3 drinks). Moderate drinking (e.g. 2-3 drinks / day in men) does not increase LPS.
  • Cut out fruit juices and fructose-rich drinks, but eating a couple of pieces of whole fruit per day is good for you
  • Add a prebiotic supplement (e.g. FOS, GOS or IOS) to your daily regime of healthy eating to decrease the toxic load both in the gut and the rest of the body
  • Add a probiotic supplement, not because they colonise, but because they interrogate the intestinal microbiome and encourage it to better behaviour which can re-establish the correct signals between the gut and the brain
  • Take a few minutes multiple times per day to close your eyes and zone out. This is instantly calming as it takes you into an alpha brain wave state and will also calm your gut bacteria.

Appendix: trusting your microbial intelligence

The researchers and clinicians speaking in this stream agreed that depression is an inside to outside problem that is exacerbated by dysbiosis (imbalance of the gut microbiome). The loss of keystone species that we have evolved with is an important contributing factor, as is the dumbing down of our dietary diversity.

I’ll leave you with what I felt was one of the most exciting pieces of information shared at this conference regarding emerging science on the true role of the appendix. Long thought of as a defunct, functionless remnant of our evolutionary progression, it appears that this organ that is so often removed if it plays up, does actually perform an incredibly important function in the body.

The appendix is actually a key immunological organ, located in a protected area at the base of the large intestine, very close to the junction of the small intestine. Due to the ileocaecal valve (ICV), it has little contact with food particles, faecal matter or any infectious diarrhoea and is now considered to be somewhat of a ‘safe house’ for good bacteria and is also involved in the formation of biofilm. This is the bacterial layer that sticks to the gut mucosa and creates the intelligent internal interface with the rest of the body. New studies are due out later this year from Professor Luis Vitetta’s group that show a distinct link between depression, appendectomies and antibiotic use. Without the ‘safe house’ of the appendix, people may struggle to repopulate their gut microbiome or generate the biofilms necessary for a healthy gut and immune system.

Whilst there is still so much we don’t know, we may just have uncovered one giant piece of our gut puzzle. Isn’t it time to trust to our internal intelligence down under?

For more information on the importance of the appendix for our immune system, check out Kooij et al’s 2016 review.

I’d particularly like to acknowledge the following speakers:

Dr Jason HawrelakMechanisms of the microbiota on mood modification

Warren MaginnHarnessing and measuring the chemistry of the gut-brain chemistry

Prof Luis VitettaMood disorders, cognition and intestinal mucosa

Dr Samantha CoulsonImpact of ageing and modern lifestyle