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How Food Affects Your Brain

Key nutrients for mood, memory and concentration

The relationship between the gut and the brain has been a hot topic in recent years. The gastrointestinal system plays an important role in brain health and the food you eat directly impacts how your brain functions. Discover what the gut-brain connection is, the importance of gut bacteria and how food affects your brain. Learn which key nutrients are needed for a healthy brain to maintain mood, memory and concentration.

The gut-brain connection

The gut-brain connection is the means by which the gut communicates with the brain, and vice versa. They are connected via the vagus nerve which is a long, wire-like nerve that starts in the amygdala in the brain (the part of the brain that processes and expresses fear and anxiety) and goes all the way down through the gastrointestinal system to the adrenal glands. Chemical messages (hormones and neurotransmitters) enable the communication and signalling to happen; 90% of the signalling is from the gut to brain and 10% comes from the brain downwards. This is why gut health is key for mood regulation and brain health.

Learn more about the gut-brain connection.

Why is it important to have healthy gut bacteria?

The gut comprises of trillions of microorganisms including bacterial species (both harmful and beneficial), fungi and viruses. The “good” bacteria help protect the body from germs and viruses, support the immune system and aid digestion. Gut microbes also metabolise bile acids (needed for fat digestion) and amino acids to produce other chemicals that affect the brain and mood.

When there is an imbalance of gut bacteria or an overgrowth of harmful bacteria, the gastrointestinal system becomes compromised and it can lead to constipation, diarrhoea, IBS, bloating, autoimmune conditions, thyroid issues, allergies, frequent infections and blood sugar imbalances.

Gut microbes also produce a neurotransmitter called gamma-aminobutyric acid (GABA), which helps control feelings of fear and anxiety.Studies have shown that certain probiotics can increase the production of GABA and reduce anxiety and depression-like symptoms.

How does food affect your brain?

Diet has a direct impact on brain health and the food you eat can significantly affect memory, learning, behaviour and mood.Foods that are high in sugar, trans fats (see below) and artificial ingredients cause inflammation in the body and the brain which can increase your risk of dementia and Alzheimer’s disease.

These types of foods also cause inflammation in the intestines which irritates the gut lining and makes it become porous (termed leaky gut syndrome). This leads to undigested food particles, toxins and bacteria being able to pass through the gut wall into the bloodstream which can trigger the immune system, causing allergic reactions and inflammation throughout the body.

High-fat and high-sugar diets have also been linked to disruptions in the blood-brain barrier; this is a membrane between the brain and body’s blood supply that protects the brain and prevents harmful substances from entering its blood supply.

The worst foods and drinks for brain health (which you should avoid) include:

  • Refined carbohydrates including pasta, bread, pastries, pizza, pies, cakes due to their high sugar content. Wholemeal carbohydrates (wholemeal pasta, bread) can be eaten in small amounts.
  • Snacks (including those marketed as healthy) such as crisps, chocolate and cakes (even “raw” versions), granola/energy/protein bars, crackers and pretzels are high in sugar and damaged oils which are not good for brain health.
  • Artificial sweeteners (especially aspartame) as they are made with chemicals and ingredients such as phenylalanine that has been linked to behavioural and cognitive issues. Phenylalanine is able to cross the blood-brain barrier and disrupt neurotransmitter production (these are the chemical messengers used by the nervous system). 
  • Sugary drinks including juices, fizzy drinks, energy drinks and sport drinks. They all contain huge amounts of sugar which is detrimental for brain health as it causes inflammation in the brain which contributes to memory loss. Another ingredient in many of these drinks is a sweetener called high-fructose corn syrup. The body does not metabolise fructose well so consuming large amounts of it can lead to diabetes, insulin resistance, high blood pressure and obesity; all of which can increase your risk of dementia. Instead, drink filtered water with lemon, peppermint or cucumber to give it more taste. Avoid sparkling water as it can negatively impact digestion, bone health and teeth due to its acidity.
  • High sugar fruits such as mangoes, lychees, passionfruit and cherries should only be eaten in small amounts. It’s much better to stick to low-sugar fruits including strawberries, raspberries, kiwi fruit and grapefruit.
  • Hydrogenated oils (also known as trans fats) are a type of unsaturated fat found in refined vegetable oils (such as rapeseed oil), margarine, baked products (muffins, pizza, cookies, cakes, pastries, doughnuts, sausage rolls), microwave popcorn, shortening, fried foods (chips, hamburgers, battered fish), coffee creamers, crisps and crackers. Trans fats are linked to reduced memory and cognitive decline; they can also increase your risk of Alzheimer’s disease.
  • Ready meals and packaged/ processed foods including sauces and condiments, instant noodles, pizzas, deli meats and hams, savoury snacks, breakfast cereals, baked beans, spaghetti hoops and tinned soups. These foods are high in sugar and salt, and often contain hydrogenated oils; all of which negatively affect brain health. Processed foods reduce the production of a brain-derived molecule called neurotrophic factor (BDNF) which is responsible for long-term memory, learning and the growth of new brain cells.
  • Pasteurised dairy products including milk, yoghurt and cheese can negatively affect the gut (and therefore brain health) as dairy is both acidic and inflammatory.
  • Certain types of fish including tuna, shark, swordfish and king mackerel as they contain high levels of mercury which is a heavy metal. Mercury accumulates in the body and gets stored in the brain, liver and kidneys; in pregnant women, mercury accumulates in the placenta and foetus. It is a neurotoxin that causes havoc to the central nervous system and damage to the brain.
  • Alcohol is very inflammatory and causes certain metabolic changes in the body. When drunk in large amounts, alcohol can damage the nerve cells of the brain (called neurons), making it difficult for brain cells to communicate. This can lead to memory loss and issues with eyesight and balance.
  • Coffee is a nervous system stimulant that triggers the stress response in the body. It can surge adrenaline and cortisol production which increases heart rate and blood pressure, and the release of glucose (sugar) into the bloodstream. Drinking coffee can interrupt sleep, negatively affect blood sugar levels and contribute to anxiety. Try a coffee alternative such as chicory root coffee (caffeine free), a turmeric latte or a ginger tea.

Adopting an organic, whole food diet that is rich in nutrients, especially antioxidants is key for brain health.

Foods that boost brain function, memory and concentration include:

  • Blueberries as they are high in a type of antioxidant called polyphenols which are beneficial for gut bacteria and cognitive function.
  • Broccoli contains glucosinolates which when broken down by the body produce isothiocyanates, a molecule that neutralises carcinogenic toxins in the body and helps lower the risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease.
  • Leafy greens (kale, spinach, rocket) are rich is essential B vitamins, vitamin E and vitamin K and an abundance of minerals which support brain health and improve memory and focus.
  • Pumpkin seedsand sunflower seeds are packed with antioxidants and minerals including magnesium, zinc, iron and copper which help protect the brain from free radical damage and facilitate effective nerve signalling. Sunflower seeds are also rich in thiamine (B1), an important vitamin for memory and cognition.
  • Brazil nuts contain ellagic acid (a type of antioxidant) which has anti-inflammatory properties to protect the brain from damage. They are also high in the mineral selenium which is needed for brain signalling pathways.
    *Nuts and seeds are best soaked overnight for at least 7 hours as it activates enzymes within the nuts and seeds to aid absorption and enable better digestion. Discard the water afterwards.
  • Food high in omega-3 fatty acids such as chia seeds, flaxseeds, walnuts and small oily fish like sardines or mackerel. Omega-3 is essential for brain health as it enables brain cells to communicate better, reduces inflammation and aids cognitive development in children and improved memory in adults.
  • Bananas are rich in the amino acid tryptophan which converts to serotonin in the body to help support healthy gut function and mood.
  • Turmeric contains curcumin, a powerful compound with anti-inflammatory and antioxidant properties which has shown to cross the blood-brain barrier to help brain cells grow, reduce mental decline and improve memory and mood.
  • Whole grains including oats, quinoa, buckwheat, barley and milletcontain an abundance of B vitamins and other minerals to reduce inflammation in the brain and improve cognitive function.
  • Beans and pulses (lentils, chickpeas, kidney beans) are high in fibre, B vitamins and omega-3. They provide a steady supply of fuel (glucose) to the brain which aids concentration and memory.


Keep your brain healthy

The food you eat impacts brain health significantly and can affect your mood, memory and behaviour. A diet that is high in sugar, unhealthy fats and junk food causes inflammation in the brain and disruptions to the blood-brain barrier. For optimal brain health and to prevent neurodegenerative disease likes dementia and Alzheimer’s, a nutrient-dense, antioxidant-rich diet is key. Regularly eat brain-boosting foods such as broccoli, blueberries, nuts, seeds, beans and pulses help keep your brain in tip-top condition.

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Blog/Article content reflects the author's research and diverse opinions, not necessarily CNM's views. Items may not be regularly updated, so represent the best available understanding at the time of publication.

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