How Diet Impacts Your Mental Health
Emily Stynes
ANutr, REGISTERED ASSOCIATED NUTRITIONIST, MSC DIETETICS STUDENT
With darker days this time of year combined with long working hours, this is more than ever the most important time to look after our mental and physical wellbeing. When thinking about the kinds of factors that can have an impact on our mood and mental state, just how powerful is our diet in promoting our mental health?
Defining Mental Health
Take a few moments to think about what springs to mind when defining the term mental health? To help us understand our mental health, a recent holistic view and definition that has shifted away from the traditional definition outlined by the world health organisation is depicted below.
Essentially three main factors encompass our mental health - our emotional, psychological and social wellbeing as they all influence the way we feel, think and behave. So how does our diet fit into all of this?
The Role of Food and Mood
The common term ‘Food and Mood’ evolved from the idea that food can affect our brains emotional and mental state by having an impact on the way we feel. Take drinking a cup of coffee or glass of wine for example, this can make us feel either good, sleepy or perhaps drowsy which demonstrates how particular compounds or combinations of compounds in foods can have an impact on our brain and mood. But, while certain compounds in alcohol and caffeine can have a relatively immediate affect our mood, this process is usually more gradual when exploring the impact of other nutrients.
Understanding the Role of Nutrients on Brain Function
There are 5 main categories of nutrients that have been shown to have on our brain function including omega-3 fatty acids, anti-oxidants, b-vitamins, proteins and carbohydrates. Here are the key things you need to know!
1. OMEGA-3 FATTY ACIDS (EPA and DHA)
The strongest evidence for the role of specific nutrients on brain health is with omega 3 fatty acids. Omega 3 fatty acids have been shown to play a crucial role in the development and maintenance of cell membranes in the brain. In particular, DHA is an omega 3 fatty acid that is essential for the growth and functional development of the brain in infants and for the maintenance of normal brain function in adults (2).
Low Mood
N-3 Polyunsaturated fatty acids also known as omega-3’s have been shown to provide beneficial effects on mood and mental state in those with severe symptoms of depression (3). But, there currently is no clear evidence to show that omega-3’s can be used a preventative treatment for low mood or depression or in those with mild to moderate symptoms also.
Degenerative Brain Conditions
In general, a poor diet and lifestyle has been suggested to be a contributing factor to the development of Alzheimer’s disease (4), the leading cause of dementia. In particular, evidence has shown that omega 3 fatty acids can play a role in the prevention of Alzheimer’s disease (AD) due to a reduction in low-grade inflammation (inflammation (a significant contributor to neuro-degenerative diseases) in the early stages of AD (4). Also, a dietary deficiency in omega-3 fatty acids has been associated with a higher risk of several mental disorders including dementia and depression (5).
Best sources of omega 3 fatty acids (EPA and DHA) include:
· Nuts and seeds including walnuts, chia seeds, flaxseeds,
· Oily fish including salmon, mackerel, herring, sardines, kippers and trout
· Plant oils including flaxseeds oil, soybean oil and canola oil
2. ANTIOXIDANTS
Antioxidants have been shown to delay or reduce age-related cognitive decline caused by free radicals, a type of molecule from that can cause oxidative damage ie destruction to the brains cells. This means that anti-oxidants can play a role in prolonging our brains health and longevity due to their anti-inflammatory effects and protection to our brains cells from damage (6).
Best Sources of Antioxidants:
Fruits, vegetables, nuts, seeds and legumes can be rich in anti-oxidants including –
· Vitamin C rich oranges, kiwis, strawberries, lemons, peppers
· Flavonoids including leafy vegetables, onions, apples, berries and soybeans
· Artichokes and coloured vegetables including red peppers, red cabbage, spinach, beetroot, kale
· Pecans, pumpkin seeds and beans
3. B-VITAMINS
The 8 essential b-vitamins work closely together to form an essential component of brain function (7). Interestingly, a dietary deficiency of B-vitamins during critical periods of development can result in permanent changes to the brain, highlighting the importance of B-vitamins for our brain function (6)! Without these vital micronutrients including vitamins B6, B12 and folic acid, our brains are more susceptible to disease and mental decline (6).
Best Dietary sources of B-vitamins B1, B3 & B12 include:
· Wholegrains, meat, fish, eggs and dairy
Dietary sources of folate include:
· Leafy green vegetables, fruit, legumes, fortified cereals
4. PROTEINS
Protein and amino acids (the building blocks of protein) have been associated with our mood and behaviour due to their role in the production of neurotransmitters (chemical messengers) in the brain. Particular research in this area has explored the role of tryptophan (an amino acid) on our serotonin (the ‘feel good’ or ‘happy’ hormone) levels which can have an impact on our mood and cognition as well as acting as a neurotransmitter between the gut-brain axis, a pathway of communication between the brain and your gut!
Evidence has shown that decreases in the amino acid tryptophan can have an impact on our mood due to a lower production of serotonin (8), highlighting the important impact of nutrients on our mood through the gut-brain axis.
Best sources of tryptophan include:
Meats - chicken, turkey and fish
Tofu and soy
Dairy - milk, cheese, eggs
Nuts and Seeds - peanuts, pumpkin and sesame seeds
5. CARBOHYDRATES
Glucose (sugar) is the main source of energy for the brain as it is required to fuel physiological brain function. Glucose also plays a role in the generation of neurotransmitters and the maintenance of brain cells (17). The type of high quality carbohydrates that can reduce spikes in blood sugar levels and in turn changes in your mood wholegrains and low glycaemic index (GI) foods which are released slowly into the bloodstream.
Best Sources of high quality carbohydrates include: Wholegrains, beans and legumes
The high fibre content of these carbohydrates sources can also promote the production of beneficial bacteria within our gut and promote interactions between our gut-brain axis, the two-way system that can play an important role in our mental health (9)! See the previous blog post on plant-based diets to find out more about including plant-based foods into your diet!
The Power of a Mediterranean Diet for our Mental Health
Recent and emerging research has delved into the impact of dietary patterns on our mental health with strong evidence showing a beneficial impact of a Mediterranean style diet on our mental health.
A recent high-quality study conducted over a 12-week period has explored the role of dietary patterns in a group of people with major clinical depression. The Mediterranean diet included the consumption of wholegrains, vegetables, fruit, beans, pulses, lentils, nuts and seeds, fish and healthy fats such as olive oil with an emphasis on reducing the intake of processed, high fat and sugar foods.
The results of this study demonstrated that the group consuming a Mediterranean style diet showed significantly greater improvements in depressive symptoms after 12 weeks when compared with the control group who received social support. What was most interesting about this study is that the degree of dietary change correlated with the degree of improvement in depression, meaning the more they changed their diet, the more their symptoms of depression improved!
Other Important Factors Impacting Mental Health
In addition to diet, there are also other important lifestyle factors that can play a significant role in our mental health.
Rest and Sleep
A lack of sleep can significantly impact your mood such as irritability, anger and potential impact on your ability to cope with stress (10). Research has shown that a regular sleep pattern can improve learning and memory (11)! It is important to get regular good quality sleep
Exercise and Daily Movement
Research has shown that exercise can enhance learning and memory and also counteract the mental decline associated with aging (12)(13) (14), emphasising the importance of daily movement and regular gym sessions!
Reduce Stress
Psychological stress can have physiological effects on the body. A clear example is the fact that stress can impact our gut via the gut-brain axis as shown for some people who have IBS (irritable bowel syndrome) (15). This is why learning to manage psychological stress with relaxation techniques and/or cognitive behavioural strategies may help to improve IBS-related symptoms (16).
Taking time out with family and friends
Social connection with others can be vital to our mental health and wellbeing.
In summary, while winter can be a challenging time for many with lower temperatures and less natural light, there a lots of things we can do to ensure that we keep ourselves mentally and physically well – and actively incorporating a healthy, balanced diet alongside exercise are most certainly top of the list!
References
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2. HEALTH BENIFITS OF DOCOSAHEXAENOIC ACID (DHA) | Elsevier Enhanced Reader [Internet]. [cited 2021 Nov 14]. Available from: https://reader.elsevier.com/reader/sd/pii/S1043661899904954?token=7175FF464BB64D400F594CB77811552FCA81806328B95F62530BEBC1065EC7F34B692C8E94315236E143F75471ABE0C0&originRegion=eu-west-1&originCreation=20211114155113
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