Our ‘Second Brain’ – And Stress, Anxiety, Depression, Mood

Our 'Second Brain' - And Stress, Anxiety, Depression, Mood

Hidden in the walls of our digestive system is something extraordinary. Scientists have known about it for a while, but new technology is taking the research to the cutting edge. What is being discovered there will revolutionise the way we think about mental and physical health. 

What happens in our head has a lot to do with what’s happening further south, in what scientists affectionately call ‘the brain in our gut’. It has a strong connection to the brain in our head and together, they are key players in mood, and mental health.

The brain in our gut, or the second brain as it is also called, is made up of more 200-600 million neurons, arranged in the intricately folded tissue that lines the gastrointestinal tract. With firepower like that, it’s not surprising that the gut does so much more than deal with food and the messier parts of being human.

It plays a critical role in mental and emotional functioning by sending information to the brain and directly influencing things like feelings of stress, anxiety and sadness, as well as memory, decision-making and learning. The brain in our gut is not capable of thought as we know it, but it communicates back and forth with our main brain, playing a critical role in our mental and emotional well-being.

Unhappy mind. Unhappy belly. Which comes first?

It’s no secret that anxiety, stress and depression often bring unhappy bellies with them, by way of irritable bowel syndrome, constipation, diarrhea, bloating and pain. For decades, doctors thought that stress, anxiety and depression were the cause, but now it seems that it’s actually the other way around. Irritation in the gastrointestinal system seems to send signals to the brain that trigger mood changes. We know that probiotics seem to alleviate the symptoms of anxiety and depression and this might be why.

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The gut is not only important for physical health, it’s also critical for mental health. What’s fascinating is the direction of influence. The longest nerve exiting the brain is called the vagus (actually they are one pair of 12 pairs of nerves that run from the brain). It runs from the brainstem to the belly and touches the heart and most major organs along the way. Here’s the fascinating part. About 90% of the fibres in the vagus, carry information from the internal organs in the chest (such as the heart) and the abdomen to the brain, not the other way around. 

Our language holds evidence of this – we were talking about it well before we knew it. If you’ve ever been directed by ‘gut instinct’, ‘gone with your gut’ to make a decision, or ‘listened to your heart’, you’re likely getting signals from this second brain in your belly. 

Messages also travel the other way, from the brain to the heart and the gut, also via the vagus nerve but without a doubt, the main direction of information flow is from the gut to the brain. 

The Role of Gut Bacteria.

As well as neurons, there is another major player in the gut-brain connection – the 100 trillion bacteria that set up home inside your gut. According to professor of physiology, psychiatry and behavioral sciences at UCLA, Emeran Mayer, gut bacteria contains phenomenal wisdom that gets sent to the brain. They affect our behaviour every minute of every day from the day we are born, and possibly before.

A Fascinating Study: From Extroversion to Introversion via the Gut

Mayer’s research has shown how the specific combinations of bacteria in the gut might influence the wiring of the brain, and in turn affect such things as temperament, mood and learning. Other researchers have also explored a possible connection between gut bacteria and behaviour, and they’ve made some remarkable discoveries.

In one study, when the gut bacteria of timid mice was transferred into the gut of extroverted mice those extroverted mice became more anxious. It also worked the other way. When the timid mice received the gut bacteria of the bold mice, the timid mice because more bold and extroverted. Aggressive mice calmed down when scientists adjusted the their gut bacteria by giving them probiotics or antibiotics.

Another Study: The Connection Between Gut Bacteria and Temperament

Research has found correlations between temperament and the presence of specific intestinal bacteria in toddlers, particularly boys. The connection was independent of history of breastfeeding, diet and the method of childbirth. Here’s what they found:

  • The children with the most genetically diverse types of gut bacteria were more positive, curious, sociable and impulsive.
  • In boys, extroversion was associated with an abundance of particular types of bacteria (Rikenellaceae and Ruminococcaceae families and Dialister and Parabacteroides genera).
  • In girls, self-restraint, cuddliness and focussed attention were associated with a lower diversity of gut bacteria.
  • Girls with an abundance of a particular family of bacteria (Rikenellaceae) seemed to be more fearful than girls who had a more balanced diversity of microbes.

This research is still in its early days, so we still don’t know what a healthy tummy would look like in terms of the combination of gut bacteria, or what factors would influence this. It is possible that the perfect balance of microbiome will vary for all of us. For this reason, the researchers caution against trying to change a child’s gut microbiome just yet.

The Gut and Depression.

Depression is widely attributed to a drop in serotonin, a neurotransmitter that is responsible for mood. What’s extraordinary is that only 5% of the body’s serotonin is stored in the brain. The other 95% of the body’s serotonin is stored in the gut. 

It’s not surprising then, that the most commonly used antidepressants that work on changing serotonin levels often come with a side of gastrointestinal issues. It’s also not surprising that the gut might play more of a role in depression than we yet realise. Research continues to look down this track for answers.

The Gut and Anxiety.

Researchers have found that young adults who eat more fermented foods (which contain probiotics) have fewer symptoms of social anxiety. As explained by Psychology Professor Matthew Milimire, ‘It is likely that the probiotics in the fermented foods are favourably changing the environment in the gut, and changes in the gut in turn influence social anxiety … the microorganisms in your gut can influence your mind.’

Food and the Comfort Factor.

The need for comfort rarely sees us diving for the celery. Pity. Instead, ‘comfort food’ tends to be high fat, high energy food. 

The relationship between food and mood isn’t all in our heads. Yes comfort food tastes delicious, smells delicious and might remind us of times we felt happy and secure, but there’s so much more to it than that, as a team of  Belgian researchers have shown.

The researchers delivered nutrients to the stomachs of participants via a nasogastric tube, with the intention of taking away the smells, tastes and memories that are typically associated with comfort food. The participants were given either ordinary saline solution or an infusion of fatty acids.  Without knowing what they were receiving through the tube, those who received the fatty acids reported half the levels of sadness and hunger compared to those who received the saline. This also showed up in brain scans. Very quickly after fatty acids hit the stomach, scans showed greater activity in the part of the brain that moderates emotions.

Stress and Food

Early research found that stressed-out mice would opt for a higher-fat food (peanut butter) over regular chow. Not surprisingly, they put on more weight than their less stressed friends. In times of stress, the gut amps up the production of ghrelin, a hormone that signals hunger to the brain. Research in humans has found similar results. In a recent study, couples were found to have significantly higher amounts of the appetite-triggering hormone following an argument. The researchers stop short of suggesting that unhealthy relationships cause poor food choices, but they acknowledge that the correlation is a strong one.

There seems to be little doubt that one of the ways stress influences behaviour is via the gut, specifically on the production of ghrelin, which sends messages to the brain around appetite and food choices.

Could gut bacteria be behind this?

Mayer points out that the last 50 years has seen a dramatic rise in autism, multiple sclerosis, Parkinsons and obesity. All of these have altered gut bacteria and brain-gut interactions. At the same time, throughout the last fifty years, we have dramatically changed the way our food is produced and processed, and the way we use antibiotics. Has the way we’re doing things lead to the dramatic increases? At this stage, it’s only speculation, but it’s an area of research that is gaining traction.

Where to now?

Mental health is not all in our head. Neither is mental illness. Finally, science is giving us real proof of this. There is little doubt that mental and emotional health is influenced by the state of our gut. The research is exciting and is promising to revolutionise treatments for a range of conditions and the way we take care of our mental health.  

The research is constantly evolving, but what we know for sure is the importance of  being attentive to the state of the gut and doing what we can to keep it healthy. It holds our second brain, and quite possibly, one of the vital keys to our mental and emotional well-being.

73 Comments

Noeleen

Oh…. my son has so many problems with ADD and drug usage…THIS would help explain and stop his depression , drug use and self harm. Thank you.

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Suzanne

For years I had many problems associated with my bowels. Usually it was constipation and lack of motility. I saw many gastroenterologists who offered very little advice. As a child I had been on antibiotics constantly, my tonsils were removed at 5 1/2 but still I would vomit, nothing helped. It took until I was in my mid 50’s to find a specialist who did breath testing for lactose and fructose malabsorptions. I tested positive to fructose malabsorption and have been much healthier and happier for the past few years. Knowing why I had suffered for most of my life from anxiety had a huge positive affect on my mental health and outlook. Changing my diet and including the right type of fermented yoghurt has improved my quality of life enormously. My bowels still are a challenge at times but my outlook on life is so much more positive and my emotions are more controlled.

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Dave

Interesting, succinct and informative. This opens up a whole new way for me to look after myself.

Thanks for writing this article in a way that makes it easy to read and understand.

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Karen Young

Generally speaking, fermented foods and foods that contain probiotics and prebiotics are good for gut health and mental health. Here is an article with some examples https://www.heysigmund.com/a-simple-way-to-reduce-social-anxiety/. If you start including fermented foods in your diet, it’s important to do it slowly. The article on the link explains why. A naturopath would be able to help you with a diet that is tailored more for you and which is more targeted for your symptoms.

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Bulbul

I have been having a bad digestive health for years and now as I am changing my diet and adding probiotics I feel my mood shift. Anxiety and depression are surfacing as the bad bacteria is being released… enema can help cleanse the colonic bad bacteria. I always feel better after enema.

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Andrea

I’ve also felt gut problem ,but I couldn’t relate all this with stress……Even I didn’t know earlier that this is happening because of stress…..I’m taking antibiotic for two years….But I can feel that belly pain or gastronomy problem is happening after stress.Your article helped me more clearly to understand about second brain….Keep sharing more articles like these…..thank you.

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Judt

Thanks for this. It’s a great article. So what is the best diet or supplements to take?

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Shiraz

Hi, I first had loose watery stools and stomach gas for about 10 days and then got into depression. This shows that the gut plays a major part in mental illness from my experience. There can be other reasons but for me it is my stomach.

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Samantha

This. This relates so much with the Serotonin Power Diet that I have been on for the last three weeks and have seen significant changes to my health (for the better) than previously. I am so glad to see more and more concrete evidence of how it is that mental illnesses are just a result of chemical imbalances and what that all means.

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Samantha

Best to look it up. High carb low fat diet. It worked well for me to get me out of the funk I was in at the time. That was four months ago. It is worth it to get out of the cycle of fatigue that you may find yourself in when life happens, but long term once your body starts feeling good again, you’ll need to start reducing it back to normal levels again.

Reply
Zorica

How would having a Gastric band effect the emotions/ depression/ anxiety based on your findings??? Please

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Karen - Hey Sigmund

It’s a very good question. I’m not familiar enough with the research around gastric banding to answer it though. A doctor or your specialist would be the best person to talk to about this.

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Karthik

Thanks for this article.

My sister practices an ancient healing art called “VARMAM” … which is being practiced in India by a few. She was telling me that her patients with depression, anxiety, stress and mood swing symptoms … all of them invariably had a very bad stomach condition.

She just administered the touch healing points for the stomach … and they become perfectly alright on the 3rd day. All happy and smiling!

Certainly probiotics is a wonderful food. In India, we take buttermilk regularly in our meals, which helps in overall wellbeing.

God Bless your good work. Your articles are very very nice! My wife keeps reading all of them regularly.

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Karen - Hey Sigmund

Thank you so much, and for sharing parts of your story. There are so many methods of healing that we need to learn more about. I love hearing when these are being practiced successfully.

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Judith

I am so happy to read this. Posted immediately. For so long I’ve been (almost yelling) “It’s not mental – it’s physical!!!” unfortunately to those very hard of hearing. ie, the experts.

Validation is so so so sweet! Thank you

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Karen - Hey Sigmund

You’re so welcome Judith. They are absolutely physical and the research is proving it over and over. I just wish there wasn’t such a lag between the research and mainstream. There are too many things that are being treated with old knowledge, without accounting for the new things that science is discovering. All the best to you.

Reply

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Behaviour is never from ‘bad’. It’s from ‘big’. Big hungry, big tired, big disconnection, big missing, big ‘too much right now’. The reason our responses might not work can often be because we’ve misread the story, or we’ve missed an important piece of it. Their story might be about now, today, yesterday, or any of the yesterdays before now. 

Our job isn’t to fix them. They aren’t broken. Our job is to understand them. Only then can we steer our response in the right direction. Otherwise we’re throwing darts at the wrong target - behaviour, instead of the need behind the behaviour. 

Watch, listen, breathe and be with. Feel what they feel. This will help them feel you with them. We all feel safer and calmer when we feel our people beside us - not judging or hurrying or questioning. What don’t you know, that they need you to know?♥️
We all have first up needs. The difference between adults and children is that we can delay the meeting of these needs for a bit longer than children - but we still need them met. 

The first most important question the brain needs answered is, ‘Is my body safe?’ - Am I free from threat, hunger, exhaustion, pain? This is usually an easier one to take care of or to recognise when it might need some attention. 

The next most important question is, ‘Is my heart safe?’ - Am I loved, noticed, valued, claimed, wanted, welcome? This can be an easy one to overlook, especially in the chaos of the morning. Of course we love them and want them - and sometimes we’ll get distracted, annoyed, frustrated, irritated. None of this changes how much we love and want them - not even for a second. We can feel two things at once - madly in love with them and annoyed/ distracted/ frustrated. Sometimes though, this can leave their ‘Is my heart safe?’ needs a little hungry. They have less capacity than us to delay the meeting of these needs. When these needs are hungry, we’ll be more likely to see big feelings or big behaviour. 

The more you can fill their love tanks at the start of the day, the more they’ll be able to handle the bumps. This doesn’t have to be big. It just has to be enough. It might look like having a cuddle, reading a story, having a chat, sitting with them while they have breakfast or while they pat the dog, touching their back when they walk past, telling them you love them.

All brains need to feel loved and wanted, and as though they aren’t a nuisance, but sometimes they’ll need to feel it more. The more their felt sense of relational safety is met, the more they’ll be able to then focus on ‘thinking brain’ things, such as planning, making good decisions, co-operating, behaving. 

(And if this today was a bumpy one, that’s okay. Those days are going to happen. If most of the time their love tanks are full, they’ll handle when it drops a little. Just top it up when you can. And don’t forget to top yours up too. Be kind to yourself. You deserve it as much as they do.)♥️
Things will always go wrong - a bad decision, a good decision with a bad outcome, a dilemma, wanting something that comes with risk. 

Often, the ‘right thing’ lives somewhere in the very blurry bounds of the grey. Sometimes it will be about what’s right for them. Sometimes what’s right for others. Sometimes it will be about taking a risk, and sometimes the ‘right’ thing just feels wrong right now, or wrong for them. Even as adults, we will often get things wrong. This isn’t because we’re bad, or because we don’t know the right thing from the wrong thing, but because few things are black and white. 

The problem with punishment and harsh consequences is that we remove ourselves as an option for them to turn to next time things end messy, or as a guide before the mess happens. 

Feeling safe in our important relationships is a primary need for all of us humans. That means making sure our relationships are free from judgement, humiliation, shame, separation. If our response to their ‘wrong things’ is to bring all of these things to the table we share with them with them, of course they’ll do anything to avoid it. This isn’t about lying or secrecy. It’s about maintaining relational ‘safety’, or closeness.

Kids want to do the right thing. They want us to love and accept them. But they’re going to get things wrong sometimes. When they do, our response will teach them either that we are safe for them to come to no matter what, or that we aren’t. 

So what do we do when things go wrong? Embrace them, reject the behaviour:

‘I love that you’ve been honest with me. That means everything to me. I know you didn’t expect things to end up like this, but here we are. Let’s talk about what’s happened and what can be different next time.’

Or, ‘Something must have made this (wrong thing) feel like the right thing to do, otherwise you wouldn’t have done it. We all do that sometimes. What do you think it was that was for you?’

Or, ‘I know you know lying isn’t okay. What made you feel like you couldn’t tell me the truth? How can we build the trust again. Let’s talk about how to do that.’

You will always be their greatest guide, but you can only be that if they let you.♥️
Whenever there is a call to courage, there will be anxiety - every time. That’s what makes it brave. This is why challenging things, brave things, important things will often drive anxiety. 

At these times - when they are safe, but doing something hard - the feelings that come with anxiety will be enough to drive avoidance. When it is avoidance of a threat, that’s important. That’s anxiety doing it’s job. But when the avoidance is in response to things that are important, brave, meaningful, that avoidance only serves to confirm the deficiency story. This is when we want to support them to take tiny steps towards that brave thing. It doesn’t have to happen all at once.l and it doesn’t matter how long it takes. Brave is about being able to handle the discomfort of anxiety enough to do the important, challenging thing. It’s built in tiny steps, one after the other. 

We don’t have to get rid of their anxiety and neither do they. They can feel anxious, and do brave. At these times (safe, but scary) they need us to take a posture of validation and confidence. ‘I believe you, and I believe in you.’ ‘I know this feels big, and I know you can handle it.’ 

What we’re saying is we know they can handle the discomfort of anxiety. They don’t have to handle it well, and they don’t have to handle it for too long. Handling it is handling it, and that’s the substance of ‘brave’. 

Being brave isn’t about doing the brave thing, but about being able to handle the discomfort of the anxiety that comes with that. And if they’ve done that today, at all, or for a moment longer than yesterday, then they’ve been brave today. It doesn’t matter how messy it was or how small it was. Let them see their brave through your eyes.‘That was big for you wasn’t it. And you did it. You felt anxious, and you stayed with it. That’s what being brave is all about.’♥️
A relationally unsafe (emotionally unsafe) environment can cause as much breakage as as a physically unsafe one. 

The brain’s priority will always be safety, so if a person or environment doesn’t feel emotionally safe, we might see big behaviour, avoidance, or reduced learning. In this case, it isn’t the child that’s broken. It’s the environment.

But here’s the thing, just because a child doesn’t feel safe, doesn’t mean the person or environment isn’t safe. What it means is that there aren’t enough signals of safety - yet, and there’s a little more work to do to build this. ‘Safety’ isn’t about what is actually safe or not, it’s about what the brain perceives. Children might have the safest, warmest, most loving adult in front of them, but that doesn’t mean they’ll feel safe. This is when we have to look at how we might extend bigger cues of warmth, welcome, inclusiveness, and what we can do (or what roles or responsibilities can we give them) to help them feel valued and needed. This might take time, and that’s okay. Children aren’t meant to feel safe with every adult in front of them, so sometimes what they need most is our patience and understanding as we continue to build this. 

This is the way it works for all of us, everywhere. None of us will be able to give our best or do our best if we don’t feel welcome, liked, valued, and free from hostility, humiliation or judgement. 

This is especially important for our schools. A brain that doesn’t feel safe can’t learn. For schools to be places of learning, they first have to be places of relationship. Before we focus too sharply on learning support and behaviour management, we first have to focus on felt sense of safety support. The most powerful way to do this is through relationship. Teachers who do this are magic-makers. They show a phenomenal capacity to expand a child’s capacity to learn, calm big behaviour, and open up a child’s world. But relationships take time, and felt safety takes time. The time it takes for this to happen is all part of the process. It’s not a waste of time, it’s the most important use of it.♥️

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