Is your diet affecting your mental health?

COVID-19 has taken its toll on many areas of our lives, including our mental health. If you have been feeling depressed or anxious lately, you are certainly not alone. Research shows that the prevalence of depressive disorder is approximately four times higher than at the same time last year. A new field of research called nutritional psychiatry has found that people’s dietary choices affect their mood. Considering the questionable food choices many of us have made during the lockdown, it’s possible that our diets have impacted more than merely our waistlines.

The brain is an astonishing factory that produces neurotransmitters such as serotonin, dopamine, noradrenaline and other brain chemicals tirelessly throughout the day. The only raw materials for these processes are nutrients, namely amino acids, vitamins and minerals, all of which we receive from the food we eat. If the brain receives the wrong amounts of these nutrients from an unhealthy diet, it will negatively impact neurotransmitter production. Put simply, what you eat directly affects the structure and function of your brain and, ultimately, your mood. If substances from processed or refined foods get to the brain, it is negatively affected. Diets high in refined sugars not only increase the risk of insulin resistance, but also promote inflammation and oxidative stress. Multiple studies have found a correlation between a diet high in refined sugars and impaired brain function and even a worsening of symptoms of mood disorders, such as depression.

Nutritional psychiatry also focuses on the link between mood and gastrointestinal (gut) health. Serotonin is a neurotransmitter that helps regulate sleep and appetite, mediate moods, and inhibit pain. About 95% of serotonin is produced in the gut. As the gut is lined with millions of nerve cells, or neurons, it makes sense that the digestive system not only helps to digest food, but also has an impact on mood. What’s more, the function of these neurons, and the production of neurotransmitters like serotonin, is affected by the billions of beneficial bacteria that make up the intestinal microbiome. These bacteria play an essential role in health. They protect the lining of the intestines to provide a strong barrier against toxins and pathogenic bacteria. They also limit inflammation, improve the absorption of nutrients and activate neural pathways that travel directly between the gut and the brain.

The risk of depression can increase substantially when you compare people with the lowest-quality diet, or what we call the Western diet, to those who eat a higher-quality, whole-foods diet. The Western diet is also known as SAD (standard American diet). The SAD is known by its excess sugar, refined carbohydrates, saturated fat and trans fats, and is the primary cause of obesity and diabetes.

Another area on which research has focussed is the relationship between obesity and mental health. People who are obese may have an increased risk of developing depression, whereas people experiencing depression may have an increased risk of becoming obese. Obesity causes the body to enter a pro-inflammatory state and inflammation is linked to depression.

Additionally, being depressed often leads to making poor food choices, like consuming sugary foods, which increase inflammation and worsen depression.

Dr Uma Naidoo is a nutritional psychiatrist and author of the new book This is your brain on food: An indispensable guide to the surprising foods that fight depression, PTSD, ADHD, anxiety, OCD and more. She uses the mnemonic BRAIN FOODS to help people remember what to eat to support good mood:

• B is for berries, which give you fibre and antioxidants.
• R is for the rainbow of colours of fruits and vegetables, which provide a diversity of fibre and nutrients.
• A is for antioxidants, which get rid of damaging compounds produced in the body.
• I is for include—remember to include lean protein.
• N is for nuts, a good source of nutrients.
• F is for fibre-rich and fermented foods, which feed the good gut bacteria.
• O is for healthy oil, such as olive oil, which has antioxidant and anti-inflammatory properties.
• O is for omega-3 fatty acid rich foods, such as oily fish, which also have an anti-inflammatory effect.
• D is for dairy, which adds good bacteria to your gut.
• S is for spices because certain spices, like turmeric, have excellent brain benefits.

Following a healthy diet can boost brain development and change brain proteins and enzymes to increase connections between brain cells. By increasing good gut bacteria, a healthy diet promotes a healthy gut biome, which decreases inflammation.

There is a wealth of evidence to show the benefits of healthy diet and lifestyle measures. Years of research has shown that these are essential for preventing cardiovascular disease, cancer, dementia, and mental health disorders, including depression and anxiety. If your mood is low, take the time to consider your diet and the effect it may be having on you. It may be time to get help from a nutritionist in addition to your psychiatrist.