Food for thought: how our diet affects our brain

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The brain is always ‘on’ – it controls our movements, thoughts, feelings and actions, our heartbeat and breathing, our sleep, and our senses. As a result, our brains need a constant supply of fuel, which it sources from the food that we eat.  The brain is the most metabolically active organ in the body. It comprises only 2% of our body weight, but this metabolic powerhouse manages to consume 25% of all the glucose in our blood.

The effects of some foods on how we think, act, and feel are well known; sugar gives us a ‘high’, caffeine stimulates the brain, and chocolate makes us happy. More recently, the idea that nutrition can elicit non-observable effects on the brain has emerged. A growing body of evidence now exists to demonstrate the effects of nutrition on brain development, mood, cognition, and ageing.

How our food affects our mood.

Our mood is the product of chemicals in the brain, including various neurotransmitters. Serotonin, known as the ‘happy hormone’, is produced in the brainstem, but has widespread effects on the brain and the body. Serotonin helps control our mood (feeling happy as well as sad), our sleep, appetite, and our memory.

Serotonin is made from tryptophan, which is an essential amino acid. Essential amino acids cannot be produced by the body, so we need to get them from the foods that we eat. Foods like chicken, fish, red meat, cheese, nuts and seeds are high in tryptophan, so their consumption allows the production of serotonin in the brain and the body.

Whilst eating a diet rich in tryptophan doesn’t necessarily increase the amount of serotonin in the brain, the inverse can have dramatic effects. The brain can’t cope with a tryptophan-free diet, and levels of serotonin will quickly decrease, resulting in irritability, anger, lowered mood, and poor memory.  

Interestingly, about 90% of the serotonin in our bodies is produced in the gastrointestinal tract, not the brain. Recently, the gut has become known for a lot more than simply digesting our food. Now dubbed the ‘mini-brain’, the gut has been shown to play a role in regulating our mood, appetite, and cravings for particular foods via the brain-gut-axis. Studies have also shown that when people supplement their diets with probiotics, or ‘good’ bacteria for the gut, they experience decreased anxiety, and improved mental outlook.

The typical ‘Western’ diet consists of highly processed food, which is high in refined sugar and saturated fats. Research has shown that this type of diet can actually affect the gut-brain signals about internal states like hunger and satiety, making it more difficult for our brain to recognise when we are full. 

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Nutrition and neuropsychology.

Nutrition can alter brain function in the short-term, by altering levels of neurotransmitters and subsequent firing of neurons, but it can also alter brain structure and function in the long-term.

The importance of proper nutrition during brain development in infants and children is well established; in babies, around 87% of their daily energy intake supplies the brain. Throughout infancy to early childhood, the growth of neurons and neuronal connectivity is at its greatest, and therefore glucose requirements are high. Poor nutrition has been shown to put children at a greater risk for mental illness, and behavioural problems like aggression and attention deficit hyper-activity disorder (ADHD). 

The food we eat has a direct effect on our cognitive functions, such as memory, attention, concentration and cognitive control. The effects of poor diet on sleep, energy and mood can also indirectly affect our daily cognitive function. Those who eat diets high in processed food, saturated fats and refined sugars have been shown to have poorer memory than those adopting a healthy, balanced diet.

The lack of sufficient nutrients can also have a toxic effect on the brain (neurotoxicity), particularly for older individuals, which predisposes the brain to atrophy (shrinkage) and premature neuronal loss. A longitudinal study found that low intake of nutritious foods, and high intake of unhealthy foods were each associated with smaller hippocampal volume; the memory centre of the brain. Recent research has focused on specific nutrients that may confer neuroprotective effects in later life, which may ameliorate neuronal loss in particular brain regions, and slow cognitive decline.

Food for thought, and healthy brain function.

A number of specific foods and nutrients have been identified to positively influence brain health, and protect against the effects of ageing on the brain.

Omega 3 fatty acids

Known as the “good fats”, Omega 3 fatty acids are found in fish, avocado and flaxseed.

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B vitamins and Folate

Folate has been shown to reduce the risk of age-related cognitive decline, and enhance the effect of antidepressant medications when used concurrently, while B vitamins are essential for a number of cellular and metabolic processes. High concentrations of folate can be found in green leafy vegetables, legumes, nuts, yeast, and wholegrains. Nuts and wholegrains are also rich in B vitamins, as are unprocessed meats, cheese, and eggs.  

Plant-based antioxidants

Various plant-based micronutrients have antioxidant properties, which can prevent oxidisation and cell damage in the brain and body. Some examples of these micronutrients include:

Polyphenols

Polyphenols are predominantly found in fruits and vegetables, especially blackberries, blueberries, raspberries and goji berries; mangoes, grapes, garlic, onions and kale. They are also found in green and black tea, as well as coffee and dark chocolate (yay!).

Curcumin

Curcumin is found in turmeric, and has been shown to promote healthy brain ageing via its anti-inflammatory properties.

Vitamin E

Vitamin E is another antioxidant that has been shown to promote healthy function in the ageing brain. You will find it in green leafy vegetables, nuts and some plant-based oils like grapeseed, sunflower, and olive oil.

Minerals

Minerals like zinc, iron and magnesium all play important roles in promoting optimal brain health and neurological function. Zinc is abundant in lean meats, seeds, nuts and oysters, while iron is found predominantly in red meats, as well as grains, nuts, and spinach. Nuts, legumes and leafy greens are also rich in magnesium.

Thankfully, there are plenty of foods on offer that are rich in nutrients that promote neurological function and healthy brain ageing. Whilst it doesn't mean we should go out and gorge on good fats until the cows come home, the next time you accidentally eat a little too much dark chocolate, or one (seven?) too many almonds, you can rest assured that your brain might actually thank you for it in the long term.

No pain, no brain: the neuropsychology of exercise

#brainspo

Most people are well acquainted with the positive effects of exercise on the body and the cardiovascular system. But how does exercise affect the brain and its cerebrovascular system; the workhorse that carries blood from the body to the brain?

There’s plenty of evidence out there telling us that what’s good for the heart is good for the brain, and that so much more is going on during exercise than that post workout high alone.

The short-term effects.

As your heart rate climbs during periods of voluntary movement and exercise, there’s an immediate and parallel increase in the production of various neurotransmitters (brain chemicals) that can have both temporary and long lasting positive effects on the brain, the mind, and the body.

Exercise is associated with increased production and release of neurotransmitters and neurotrophic factors (proteins that support the growth and survival of neurons) in the brain. There is also evidence to suggest that increases in both of these things can promote neuronal growth and neuroplasticity (the brain’s ability to reorganise itself by forming new neural connections). So in much the same way as consistent exercise promotes muscle strength and growth in the body, it also creates a parallel growth and strengthening of neural connections within the brain.

Consistent with the ‘brain-as-a-muscle’ analogy, many studies have suggested that the areas of the brain that underpin higher-order thinking skills (the pre-frontal cortex) and memory abilities (the medial temporal lobes and hippocampi) are larger in individuals who exercise regularly.

While endorphins get most of the credit for the post-exercise rush, these pain-fighting, mood-enhancing peptides actually only play a minor part. Increases in other types of neurotransmitters have various and combined effects on the brain, and in turn, our mood. For example, dopamine and norepinephrine work together as the ‘feel-good’ combo that results in ‘runners-high’, while GABA (Gamma-Aminobutyric Acid) acts as a ‘calming’ or inhibitory chemical that can increase relaxation and help build immunity to stress.

While all of these positive chemicals are increasing in concentration in the brain during exercise, our stress hormones (cortisol and adrenaline) decrease after regular exercise, further enhancing the stress-relieving, neuroprotective benefits we reap in the aftermath.

The longer-term bonuses.

The neurogenesis and neuroplasticity that exercise promotes are not limited to short-term effects. Neuronal growth, strengthening and reorganisation can increase stress tolerance and enhance cognitive function (e.g. memory, attention, concentration, mental flexibility, and inhibitory control) long after you’ve finished your run. As a result, evidence has shown that exercise promotes improved cognition and academic performance in children, increased productivity in adults, and delays cognitive decline in older individuals.

Exercise also reduces your cardiovascular risk factors; it helps lower blood pressure, heart rate and cholesterol. This reduces the chance of stroke and heart disease, while preserving cognitive function and quality of life across the lifespan.

In an interesting recent study, researchers found exercise to increase levels of GABA and glutamate (another neurotransmitter), both of which are known to be depleted in the brains of individuals with mood and anxiety disorders. Using MR spectroscopy, they demonstrated increased concentrations of GABA and glutamate after exercise in areas of the brain that underpin processing of visual information, emotions, and specific cognitive functions.

Improved mood and lowered anxiety have also been shown to promote adherence to regular exercise programs, showing us that it’s not just an empty motivational spiel, but working out does actually get easier the more you do it!  

Finally, regular exercise can also increase your pain tolerance, and who wouldn’t say yes to that? A recent meta-analysis demonstrated that while athletes experience pain similarly to other active adults, their ability to withstand pain was significantly greater. Another study showed that in a group of healthy adults following a 6-week structured training schedule, pain tolerance increased significantly at the completion of the program.

The verdict's in...

The brain, the mind and the body all reap countless benefits from regular exercise, and there’s no shortage of evidence to prove the case. The best part is, even 20 to 30 minute bursts of regular exercise are all you need to get your brain and body pumping to their maximum potential.

Welcome!

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Hello!

Thanks for stopping by and checking out my new brainchild that is the Brain, Mind & Body blog. This is just a quick post to say hello and to introduce myself, and a little of the inspiration behind BM&B.

My name is Cynthia and I’m a clinical neuropsychology registrar currently working in clinical research into Frontotemporal dementia and related disorders (among other things). I live in Sydney with my partner, but Melbourne has my heart and will always be ‘home’ for me.

So why blog?

There are a couple of reasons I decided to start this blog, the first of which is my revived love of writing. Throughout university and since graduating, the only writing I’ve been required to do has been ‘scientifically’ oriented, which imposes certain restrictions on creativity and flair. Whilst scientific writing obviously has its place in academic journals, theses and the like, it doesn’t flow quite as freely, nor is it quite as accessible for everyone.

I was recently lucky enough to write an article for The Conversation (I’ve since posted it here), who are an online source of news and reviews written by those in the research community delivered in plain language direct to the public. Their byline is “academic rigour, journalistic flair”. It wasn’t until I sat down to write the article that my enjoyment of writing in this style was properly realised.

The second reason for this blog is my love and passion for all things brain. Having dedicated my studies and career so far to the inner and outer workings of the brain, I’m yet to learn something about it that doesn’t interest and inspire me. The mind and body are inherently and reciprocally connected to the brain; you can’t have one without the other. It’s this reciprocal relationship between the three that inspired me to combine my knowledge and passion for writing and start communicating what I know.

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So much of what is discovered via research is hidden away in academic and scientific journals, making it difficult to access for anyone other than those in an academic institution. I want this blog to serve as a gateway, from research to practice, and from science to real-life knowledge and application of what is known about the brain, mind and body.

What will you find here?

Variety! From memory, sleep, exercise, food and brain health, to neuroplasticity, mindfulness, hardwiring happiness, brain training, dementia, to the effects of depression, anxiety and stress on the brain and body; the possibilities are endless! My goal is to translate this knowledge into meaningful real-world application to promote healthy brains, minds and bodies.

So stay tuned, I plan on making my way through a whole range of different and diverse topics that I hope will be relevant to all of you.

I hope this little intro has been helpful, and that it has given you some insight into who I am, and what makes me tick. Please feel free to leave questions, comments and thoughts on any or all of the topics I touch on.

Happy discovering!

Cynthia xx

P.S. Creating this blog was in part inspired by a friend and colleague who gave me the encouragement I needed to follow the ‘YESes’ and do something that excites me. She has created a phenomenal mind, body, soul coaching business and you can find her website here.

Special mention also goes to another friend, colleague and fellow researcher whose own experience of having a blog inspired me to start my own. I love reading her posts, and you can find her blog over here.

Fight, flight or … faint? Why some people pass out when they see blood or feel pain

Most people find the sight of blood or a hypodermic needle enough to cause some discomfort, but why do some people faint when faced with them? If you’re someone who finds yourself sweating about your upcoming flu jab, you might have your prehistoric ancestors to thank.
Phobias are part of the anxiety disorder family. They are thought to arise because of a learned response to a stimulus following a traumatic event (being bitten by a dog might lead to a fear of dogs), or because of intrinsic adaptive mechanisms that promote survival, which might underlie a fear of spiders or heights.
Most people are familiar with the experience of fear. It may be fear of an upcoming presentation, or of a mouse running across your kitchen floor. Fear is a basic emotion central to the experience of threat, where an animal either fights the threat or runs away.
A phobia, on the other hand, is an intense, pervasive and debilitating fear of something that might seem entirely harmless to others.

The blood-injection-injury phobia

The blood-injection-injury phobia is a fairly common phenomenon. It is experienced by approximately 3% of the population. The phobia can be triggered by the sight of blood, by sustaining an injury, receiving an injection, or some other type of medical procedure.
All humans have a natural tendency to be squeamish in these situations, but for some people the response is more extreme. They experience a temporary spike in heart rate and blood pressure, followed by a dramatic drop. This results in skin pallour, sweating, nausea and fainting.
This fainting response is unique to the blood-injection-injury phobia, in contrast with the usual acceleration of heart rate and elevation in blood pressure in all other phobias.
So why does a fear of blood or needles leave a person weak at the knees, while confrontation with a spider or a Ferris wheel leaves the body armed and ready to fight or run away?
The earliest “adaptationist” hypothesis to explain the blood-injection-injury phobia suggests fainting at the sight of blood increases the chance of survival, because a dramatic drop in blood pressure minimises blood loss in the case of injury. However, this does not explain why people faint when faced with needles or minor injuries, where little or no blood loss is involved.
The second evolutionary hypothesis posits that blood-induced fainting in mammals is controlled by the same physiological mechanism that regulates disgust. It suggests that, in some people, the sight of their own (or another’s) blood might induce a disgust response.
However, disgust (and associated nausea and vomiting) is thought to have evolved to protect mammals from the risk of disease-laden food. It’s difficult to imagine the adaptive benefit of fainting when confronted with bad chicken; simple avoidance seems like a much better approach to maintaining health and survival.
A third explanation describes the adaptive benefit of fainting during periods of inescapable threat in the mid-Paleolithic era. During warfare, confrontation with a “stranger wielding a sharp object” was likely to be associated with threat to life. Humans' tendency to faint (or “play dead”), rather than attempt to flee or fight, may therefore have evolved as an alternative stress-induced fear-circuitry response.
Epidemiological studies have consistently shown a higher prevalence of blood-injection-injury phobia in women compared with men. Prevalence of the blood-injection-injury phobia also decreases after puberty in boys.
The Paleolothic-threat hypothesis suggests that, during warfare, a phobic response to the sight of blood or an approaching sharp object was likely to be maladaptive for men who engaged in combat. For women and children, however, this behaviour may have been adaptive; fear-induced fainting may have increased the likelihood of being taken captive rather than being killed.
In an interesting research experiment, blood donors were more likely to faint when blood was collected by an experienced phlebotomist rather than an inexperienced phlebotomist.
Consistent with the Paleolithic-threat hypothesis, it was concluded that the novice phlebotomist may have a more deliberate, slower-moving and more talkative approach than their more experienced counterparts. A sharp object held by a fast-moving, non-communicative stranger may resemble more closely a mid-Paleolithic assailant signalling life-threatening danger.

Why do only some people faint?

Heritability estimates are high in the blood-injection-injury phobia; many people report strong family histories, and concurrence of this phobia is high among twins.
Specific phobias, including the blood-injection-injury phobia, are frequently associated with a range of other mental health problems, particularly anxiety disorders. Phobias are also more common in individuals who have endured abuse, neglect or trauma in early life.
Some people might actually be predisposed to fainting due to a dysregulation in their autonomic nervous system. The blood-injection-injury phobia appears to develop in these individuals as a conditioned fear response, after they endure repeated traumatic fainting episodes.
Given its trademark physiological response, traditional methods of relaxation and deep breathing techniques are not the best approach when it comes to a fear of blood, needles or medical procedures. You might find yourself slowing your heart rate and inadvertently accelerating your trip to the floor.
Instead, engaging in conversation, increasing muscle tone and maintaining tension in your body will keep your heart rate up and your dizziness at bay. This could even provide you with enough distraction until it’s all over.

Cynthia Murray, Clinical Neuropsychology Registrar and Research Assistant, Neuroscience Research Australia
This article was originally published on The Conversation. Read the original article.