Gut bacteria play a vital role to your health
FOR generations, we’ve been programmed to think of our gut as a place where bacteria proliferate. But research has shown it plays a vital role to our health.
We’ve long realised its importance to our digestive wellbeing. That’s why so many of us have added probiotic yoghurts to our diets. What we’re now beginning to understand is how important it is to our brain health too.
In his new book, Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain — For Life American neurologist David Perlmutter summarises the latest research into how our diet influences our gut, how our gut affects our brain and ultimately how what we eat can keep our brain healthy.
“We’ve been taught to think of bacteria as agents of death,” says Dr Perlmutter. “But the time has come to embrace another side of their story. Some bugs are fundamental to life. Just as we can say that disease begins in the gut, so too does health and vitality.”
There are at least 10,000 different species living in the human gut. These species are collectively known as the microbiome. They include yeasts, parasites and viruses but mostly consist of bacteria.
These bacteria aid in the digestion and absorption of nutrients. They create a physical barrier against potential invaders such as pathogenic bacteria, harmful viruses and dangerous parasites. And they influence our immune response by controlling our body’s inflammatory pathways.
In this way, they affect our risk for chronic disease.
Our brain depends on them, too. Gut bacteria produce and release important enzymes and chemicals for the brain, including vitamins, neurotransmitters and short-chain fatty acids.
The gut is in constant communication with the brain. So much so that it’s recognised as the body’s other nervous system. The central nervous system consists of the brain and spinal cord, while the enteric nervous system is made up of the gut.
Both systems are connected by the vagus nerve, which runs from the brain to the abdomen. The gut uses this nerve to direct bodily processes such as regulating muscles, autoimmune responses and hormones.
And because the microbiome controls the gut, it controls these various bodily processes too.
That’s not all it controls. An imbalance of gut bacteria has been linked to brain disorders such as autism, dementia and depression. Studies have also shown that rebalancing the gut with beneficial bacteria can improve brain health, mood, memory and concentration.
If you stop to think, you’ll realise you already know your brain is connected to your gut. “Just think of the last time you felt sick to your stomach because you were nervous, scared or even elated,” says Dr Perlmutter.
“Maybe it was before taking an important exam or getting married. Scientists are now learning that the relationship between the brain and gut is bi-directional. Just as your brain can send butterflies to your stomach, your gut can relay its state of clam or alarm to your brain and nervous system.”
What this means is that when the microbiome becomes imbalanced, it affects the immune system, causing inflammation and the release of free radicals in the body. These two mechanisms are the leading cause of deterioration in the brain.
Dr Perlmutter gives many examples of studies proving this in his book. One involves rats which were bred to have no bacteria at all. They suffer from acute anxiety, an inability to handle stress, chronic gut and general inflammation and lower levels of brain-growth hormones as a result.
A molecule called lipopolysaccharide (LPS) is involved in this inflammation process. LPS is produced in the gut and is normally blocked from gaining entry to the bloodstream.
However, an imbalanced microbiome can lead to leakage and elevated LPS levels are seen in the blood of those diagnosed with conditions as diverse as Alzheimer’s disease, multiple sclerosis and autism.
Dr Perlmutter has a particular interest in the role bacteria may play in autism. He refers to studies showing elevated levels of clostridia in the microbiome of children with autism. These bacteria produce large amounts of propionic aid, which is known to be toxic to the brain.
He suggests this may explain why autistic children crave carbohydrates, which feed the clostridia bacterium, creating a vicious cycle by fuelling the growth of more bacteria which produce more propionic acid.
Dr Perlmutter may be the first to bring all of this research together in one volume but he isn’t the only person working in this field. UCC’s Alimentary Pharmabiotic Centre is at the forefront of research in this area.
Professor Paul O’Toole is involved in UCC’s Eldermet project. “This project looked at the gut bacteria of 500 people aged over 65,” explains Professor O’Toole. “We found that those who were healthy had a diverse diet and diverse microbiota.”
There were problems with those living in long-term residential care. Their low-diversity diets led to low-diversity microbiota. In particular, they lacked bacteria to break fibre down into short-chain fatty acids, which are vital for energy and health. This made them frail.
“We see the microbiome as a rainforest,” says Professor O’Toole. “Hack down half the trees and you’ll inevitably change the ecosystem. Narrow your diet and you’ll do the same to your gut bacteria.”
Psychiatrist Ted Dinan, who works with Professor O’Toole, specialises in the role gut bacteria play in mental health.
He refers to studies showing elevated cortisol levels in those suffering from major depressive episodes. “Recently, it’s been proven that a probiotic cocktail of Lactobacillus Helvetius and Bifidobacterium longum reduces cortisol levels,” he says.
“Then there’s the fact that many of the physiological and psychological processes associated with depression can be traced back to a deficiency of the neurotransmitter GABA. There are gut microbes which secrete GABA and there are other microbes such as Bifidobacterium infantis, which alter levels of serotonin just like Prozac does.”
Research carried out at the Alimentary Pharmabiotic Centre has shown that diet is a key way in which we can improve gut bacteria and levels of overall health.
“Some probiotics have enormous health implications for the future of psychiatric medicine,” says Dr Dinan. “Stress, for example, affects the microbiome but these factors can be reversed by probiotic agents such as lactobacillus farciminis.”
Professor O’Toole is currently working on a follow-on project, Elderfood with the aim to develop foods to positively impact on gut health.
“Right now, we think diet is the major factor in gut health,” he says. “We recommend increasing intake of fibre, complex carbohydrates, fish oils and fresh fruit and vegetables. It’s all about a diet that’s diverse in colour and content.”
Dr Perlmutter agrees. “Anyone can change the state of their microbiome and health through dietary choices,” he insists.
He advises introducing brain-sustaining foods such as probiotics, prebiotics, fermented foods, leafy greens, healthful fat and even a daily glass of red wine.
These will help maintain a diverse and balanced microbiome. He also recommends avoiding aspects of modern-day living that have a detrimental effect on the microbiome. One of these is antibiotics.
“Antibiotics can cure many serious, life-threatening illness but they are often overused which has led to the proliferation of antibiotic-resistant pathogens,” he says. “Their overuse in agriculture means they make their way into our food supply too.”
For this reason, he recommends taking antibiotics only when absolutely necessary and always choosing antibiotic-free meat.
“We have evolved with microorganisms over millions of years,” says Dr Perlmutter.
“They are as much part of our survival as our own cells are. We need to start looking after them and research has shown that significant changes in the array of gut bacteria can take place in as little as six days.”
Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain — For Life by David Perlmutter, Yellow Kite Publications.`
The basic principles:
Drink red wine. It’s rich in polyphenols, which help stabilise the lining of the gut and counterbalance clostridial species in the microbiome. Limit it to a glass a day for women and two for men.
Dark chocolate, tea and coffee are rich in polyphenols too.
Pile your plate high with brain-maker foods such as leafy greens and lettuces, broccoli, spinach, Brussel sprouts, green beans, asparagus, garlic, leeks, ginger, shallots and parsley.
Eat low-sugar fruits such as avocado, peppers, cucumbers, tomatoes, courgettes, squash, lemon and lime.
Embrace healthy fats such as extra virgin olive oil, sesame oil, coconut oil, butter, almond milk, olives, nuts and nut butters, cheese (except for blue cheese) and seeds such as pumpkin, chia and sunflower.
Choose foods rich in prebiotics, which fuel the growth and activity of good gut bacteria. These foods include acacia gum, raw chicory root, raw Jerusalem artichoke, raw dandelion greens, raw garlic, raw leek, raw onion, cooked onion and raw asparagus.
Eat fermented foods, which provide beneficial bacteria and kill off harmful bacteria. These foods include live-cultured yoghurt, kefir, kombucha tea, tempeh, kimchi, sauerkraut, pickles, fermented meat, fish and eggs and cultured condiments such as mustard, horseradish and relish.
Minimise your intake of refined sugars and use natural stevia, chocolate, whole sweet fruit and berries as sweeteners instead. Avoid added sugars, chemical preservatives and colourings. Ideally, choose organic.
Dr Perlmutter also recommends intermittent fasting, which has been shown to increase strains of beneficial bacteria and reduce bacteria. that have a negative effect on health.
