As the COVID-19 pandemic stretches on, the bad news is that the disruption in our daily lives, relationships and workplaces is taking a mental toll. We are all faced with different manifestations of mental challenges such as increased irritability, emotional exhaustion, exacerbation of pre-existing conditions, poor concentration and poor sleep.

The good news is that stress and feelings associated with it are not a sign of weakness, but a normal reaction to difficult times and can be managed. We can adopt several ways to improve our mood and cope with stress. One solution, well documented and backed by research, is to maintain a nutritious, well-balanced diet that can improve brain function, shore up immunity, lower blood pressure, improve circulation and reduce toxins from the body.

When we speak of diet and health, we usually think of it as prevention for illnesses such as heart diseases, diabetes, cancer, obesity and so on. We rarely and consciously relate diet with our mood. But food has a major impact on our everyday mood changes. Specific nutrients play a very important role in reducing the levels of cortisol, adrenalin and the stress chemicals in our body that activate fight and flight response. The nutrients such as complex carbohydrates, proteins, iron, vitamin B and C, magnesium, selenium and omega 3 fatty acids play a very specific and significant role in helping improve our mood and reducing stress levels.

Fuel for the body and mind - how does it work?

The major constituents of our usual diet - proteins (e.g. meat, fish, eggs, pulses, beans), carbohydrates (e.g. rice, potatoes, bread, pasta) and fats (e.g. cooking oil, ghee, butter) serve not only as an energy source but as precursors to a variety of neuro-active substances.

When we do not take enough nutrient-rich foods, our body may lack vital vitamins and minerals, often affecting our energy, mood and brain function. Several nutritional deficiencies, such as vitamin B9 (folate), B12 and zinc can cause symptoms of depression and dementia such as low mood, fatigue, cognitive decline, and irritability.

The brain is an organ with very high metabolic and nutrient demands. On average, the brain consumes 20% of a person's daily caloric intake, approximately 400 calories per day. It is composed of 60% fat and contains high concentrations of cholesterol and polyunsaturated fatty acids (PUFAs) such as omega-3s.

Our brains need an adequate supply of energy that is needed to help us concentrate and focus. This energy comes from glucose in our blood. We get that glucose from the carbohydrates – mainly bread, rice, potatoes, sugars, cereals also from fruits, vegetables and lactose in milk.

Regular meals containing carbohydrate ensures we have enough glucose in our blood. It is important to ensure we are eating healthy sources of complex carbohydrates such as whole grains, vegetables, fruits, legumes and low fat dairy.

Another name to keep in mind is serotonin, the chemical messenger in the brain that controls various body functions including appetite, body temperature, libido and mood. Serotonin is made with a part of protein from the diet (tryptophan) and the more carbohydrate-rich food we consume, the higher amount of serotonin that may find its way to our brain.

Serotonin is considered to be the brain's natural 'feel good' chemical and appetite suppressant. Complex carbohydrates take a longer time to get digested and, therefore, keep a person calm for a longer time. Complex carbohydrates also stabilise blood sugar levels.

Why do we crave sweets?                                            

The concept is not to have a lot of sugar to improve our mood but to have an adequate amount of complex carbohydrates to ensure a normal level of glucose for the brain.

By adequate amount we mean, about 130 grams/day of carbohydrate is required to supply the energy demands of the brain (e.g 1 slice of bread = 15 grams of carbohydrate, 100 grams of cooked rice = 30 grams of carbohydrates).

So, there is no need to have excess or refined sugar (added sugar from cakes, biscuits, pastries, fruit juices) from processed foods. Research indicates a diet high in sugar is linked to lower levels of brain-derived neurotrophic factor (BDNF) without which our brain is unable to learn new things and form new memories. BDNF is low in people suffering from diabetes and also pre-diabetes. Lower levels of BDNF is also linked to depression and dementia.

Obesity is linked to chronic consumption of added sugar because obesity reduces the activity of anorexigenic oxytocin system which is responsible for 'telling' us when to stop eating or not to overeat.

Certain vitamin and mineral deficiencies affect brain function and mood

Iron: Iron deficiency anaemia leads to lethargy and weakness. Adequate iron can be obtained from red meat, poultry and fish, beans and pulses, fortified cereals. Avoiding tea and coffee with meals may also be helpful.

Omega 3 fatty acids: The brain needs omega 3 fatty acids for the formation of healthy nerve cells. Research shows they are associated with a lower risk of depression. Sources of omega 3 fatty acids can be oily fish, nuts and seeds like flax and chia seeds, walnuts, soybean and canola oil.

All vitamin Bs: Deficiencies impact the nervous system and lead to stress-related symptoms such as irritability, lethargy and depression. B vitamins maintain regular blood sugar levels, keeps energy and mood stable. B3 (Niacin) deficiencies may lead to disorientation and depression. B5 (pantothenic acid) improves coping mechanisms. B9 (folate) relieves stress, anxiety, panic and even depression. B12 (cobalamin) eases mood changes. Sources include yeast, meat, poultry, legumes, kidney beans, wholemeal bread, broccoli, Brussels sprouts, dark green cabbage, peanuts, peas, egg yolks and green leafy vegetables.

Vitamin C: Both emotional and physical stress depletes vitamin C status in the body and reduces its resistance to infection and disease. Vitamin C supports adrenal glands allowing quicker recovery and lower fatigue levels. Rich sources include guava, pepper (capsicum), oranges, lemon, strawberries, tomato, papaya and broccoli.

Magnesium: Stimulation of stress hormone from both physical and psychological stress increases magnesium depletion from the heart and other vital organs increasing dietary requirements for magnesium. Research indicates magnesium reduces stress and anxiety and improves the quality of sleep. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains include magnesium.

Zinc: Depression and zinc are related as it activates neurotransmitters signalling pathway in the gut which regulates brain functions like appetite, sleep, neurogenesis, cognitive function and mood. Oysters, red meat, poultry, chickpeas and nuts (cashew and almonds) are excellent sources of zinc.

There is a strong link between our diet and mood, but it is specific to each individual and compounded by specific health issues. But one message is clear, by keeping an eye on what we eat we can stop emotional eating from stress and choose healthier alternatives.

The writer worked in the NHS, United Kingdom as a registered clinical dietician. She is currently a Visiting Specialist at Praava Health, Bangladesh.

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