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Writer's pictureRebecca Hills

How poor nutrition fuels anxiety: What you need to know

Anxiety can feel overwhelming, leaving you restless, on edge or unable to focus.


Many people don’t realise that what you eat could be playing a big role in how you feel.


While anxiety has many causes, your diet can significantly impact your brain and body, often making symptoms worse.


If you’ve ever wondered why your mood seems tied to your eating habits, the answer lies in how your brain works and what it needs to function well.


Here’s a simple look at how poor nutrition can fuel anxiety and why your diet matters.


How poor nutrition fuels anxiety: What you need to know

The gut-brain connection


Your digestive system and brain are closely connected through what’s called the gut-brain axis.


You may have heard of serotonin – a chemical that helps you feel calm and happy. Most of your body's serotonin is made in your gut by your microbiome – the microorganisms including bacteria, viruses, fungi, and other microbes that live in your gut.


Your gut microbiome is also responsible for producing other mood-altering neurotransmitters (chemicals that send messages between nerve cells) such as dopamine, as well as short-chain fatty acids, which reduce inflammation and support brain health.


When your diet is full of processed foods or low in nutrients, it can upset the balance of your gut microbiome, affecting how your brain functions and potentially increasing feelings of anxiety.


Blood sugar 'rollercoaster'


Have you ever felt irritable, anxious or even shaky when you're hungry or after eating?


This happens because your brain relies on a steady supply of glucose (the simplest form of sugar) for energy.


When you eat foods that are high in sugar or refined carbohydrates – like pastries, white bread or sugary drinks – these are digested quickly, and your blood sugar levels also rise quickly.


This causes a burst of energy... but, it is short-lived.


Your body responds by releasing insulin to bring your blood sugar levels back down, but this process can overshoot, leaving your blood sugar lower than it was before.


This drop, often referred to as a 'crash', can make you feel irritable, fatigued and anxious.


These rapid swings in blood sugar don’t just affect your energy, they affect your brain function.


The brain needs a constant, stable supply of glucose to function well.


When your blood sugar drops too low, your brain can become under-fuelled, which triggers a stress response in the body.


This triggers the release of stress hormones like cortisol and adrenaline, which are part of the body's fight-or-flight response.


This can make you feel anxious, nervous or jittery.


In addition, this rollercoaster of blood sugar fluctuations can increase inflammation in the body, which has been linked to mood disorders, including anxiety. Over time, eating a diet high in sugar and refined carbohydrates can lead to chronic low-grade inflammation, which further impacts brain function, making it harder for you to stay calm and focused.


Missing key nutrients


Your brain needs certain vitamins and minerals to function at its best.


If your diet is missing these nutrients, it can affect how your brain processes thoughts and emotions.


For example:


  • Magnesium: This mineral helps your body stay calm and manage stress. Low magnesium levels can increase the release of stress hormones like cortisol, making you feel more anxious.


  • Zinc: Important for brain health, zinc helps your body regulate mood.


  • B vitamins: These are crucial for producing serotonin and dopamine, which help you feel balanced and happy.


Eating a balanced diet is key to obtaining all the nutrients you need. Read my blog post What is a balanced plate for someone in midlife? for guidance with this.


Missing fatty acids


Your brain is made up of about 60% fat, which means it relies heavily on healthy fats to function properly.


Omega-3 fatty acids, found in foods like oily fish (such as salmon, anchovies and mackerel), walnuts, flaxseeds, and chia seeds, are essential for maintaining brain health and regulating mood.


These omega-3 fatty acids help to build and maintain the brain's cell membranes, ensuring that your brain cells communicate effectively with each other.


They also play a role in the production of neurotransmitters like serotonin and dopamine, which as mentioned earlier are are critical for stabilising mood and reducing anxiety.


Without sufficient omega-3s, these processes can become disrupted, potentially leading to mood imbalances.


In addition, omega-3s have anti-inflammatory properties, which leads me nicely to the next section...


Chronic inflammation and anxiety


A diet high in processed foods, unhealthy fats and refined sugars can lead to chronic low-grade inflammation throughout the body, including the brain.


While inflammation is part of the body’s natural healing process, when it becomes chronic it can interfere with normal brain function and mood regulation.


The brain, like the rest of the body, is sensitive to inflammation.


When the brain becomes inflamed, it can disrupt the delicate balance of neurotransmitters and this has been linked to the development and worsening of mental health conditions like anxiety and depression.


Certain foods, such as those high in trans fats, refined sugars and artificial additives, can trigger this chronic inflammation.


Chronic inflammation can also affect the body’s ability to manage stress.


For instance, it can increase the production of the stress hormone cortisol, which in turn can make anxiety worse.


By adopting an anti-inflammatory diet rich in whole foods, healthy fats and antioxidants you can help reduce inflammation in the body and promote better mental health.


Caffeine and dehydration


If you’re already feeling anxious, caffeine can make it worse.


It’s a stimulant, which means it activates your body’s fight or flight response, leaving you feeling jittery, restless or on edge.


On top of that, even mild dehydration can affect your mood and concentration.


Your brain needs water to stay sharp, so skipping on hydration can add to stress and irritability.

Why your diet matters


Anxiety is complex, and your diet is just one piece of the puzzle.


But understanding how your food choices affect your mood can help you feel more in control.


By making small changes to your eating habits, you can give your brain the support it needs to help you feel calmer and more balanced.


Disclaimer


The information and advice I provided here is of a general nature and should never replace individual health or medical advice provided by your doctor or other healthcare professional involved in your care.

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