Nutrition and Mental Health: What is the Connection?
The winter blues are real. The cold temperature and reduced daylight can make getting active outside and absorbing that much needed vitamin D from sunshine very difficult. Roughly 2-3% of Canadians experience seasonal affective disorder (SAD) each year[1], which is a kind of depression that occurs commonly in the Winter months. According to the Canadian Mental Health Association, 10% of reported depression is classified as SAD1. Mental health is important, and as a registered dietitian, I know that nutrition can play an important role, but it it's not the only factor at play.
Much of the research on mental health and nutrition has (unfortunately) weak evidence. That’s not to say there isn’t a connection, but it’s important to note the difference between correlation and causation. In simple terms, it’s the age-old debate of chicken or egg – what comes first? Poor diet can present with depression and anxiety, but depression and anxiety can also result in poor diet. With all that said, let’s chat about what we do know about nutrition and mental health.
What is mental health?
So, what exactly is mental health? According to the World Health Organization (WHO) mental health is a “state of mental well-being that enables people to cope with the stresses of life, realize their abilities, learn well and work well, and contribute to their community”[2]. It’s also defined as a basic human right. Brain health, on the other hand, is about supporting brain function and brain chemistry, and a key part of this is consuming foods that help reduce inflammation and support the creation of neurotransmitters in our bodies.
The role of the Omega-3 fatty acid, DHA
Our brains are the most complex part of the human body. Interestingly, docosahexaenoic acid (DHA)—you’ve probably heard of this Omega-3 fatty acid being abundant in oily fish—is the most abundant polyunsaturated fatty acid in the brain. While DHA is found throughout the brain, there are high levels in the “grey matter”, which plays a significant role in our movement, memory formations, and emotion regulation[3].
If you’ve been pregnant before, you may have taken an omega-3 supplement containing DHA during pregnancy (or chosen to consume 2-3 servings of oily fish per week). Omega-3s, such as DHA and eicosapentaenoic acid (EPA) are essential fatty acids that help with proper brain, eye, and nerve development, as well as cardiovascular health, which is why it’s recommended to be extra diligent with it during pregnancy.
Omega-3 fatty acids are also known to help with inflammation, which helps to protect the brain from damage. Omega-3 fatty acids have also been shown to positively affect serotonin (happiness hormone) and dopamine (feel-good hormone) neurotransmission[4]. Research in omega-3 (DHA) supplementation for neuropsychiatric conditions, like Alzheimer’s, dementia, and mood disorders is always ongoing. My recommendation is to aim to include omega-3’s in your diet through the consumption of cold water fatty fish at least twice per week. Example of omega rich fish include salmon (my favourite), mackerel, herring, and sardines. If you’re not a fan of fish that’s okay, try taking a supplement that provides approximately 1 gram EPA/DHA combined.
The role of protein-rich foods:
As a dietitian I’m always touting the benefits of a “balanced meal” or “balanced snack” that contains protein. Protein is macronutrient that is basically the building blocks of your muscles, organs, skin and other tissues. Protein also helps to keep you fuller and more satisfied after meals and snacks, and helps to stabilize your blood sugar levels (and mood!) throughout the day too. When you don’t consume enough, you may feel moody, hungry, lacking energy and sort of like we’re on an emotional rollercoaster. Make sure that you include protein-rich foods like meat, poultry, fish, beans, lentils, tofu, eggs and nuts/seeds in each meal and snack to feel more emotionally (and physically) stable during the day.
The “brain-gut connection”
Have you ever heard the phrase “gut feeling”? Our brain and gut are actually deeply connected, and we often refer to our gut as our “second brain”. The connection between our brain and gut is called the gut-brain axis (GBA), which simply means that they connect and communicate with eachother. Neurotransmitters, or chemical messengers, like serotonin and dopamine, are produced by the gut microbiota[5]. In fact, more than 90% of serotonin is synthesized in the gut!
This means taking care of your gut health may impact mental health--if not directly--in how you feel from a gastrointestinal point of view (which can indirectly affect your mental health. A happy gut is one that has plenty of beneficial bacteria, so the best way to support your gut health is to consume plenty of fibre-rich foods. Not only does fibre help to create, form, and facilitate the passage of stool, but it also helps to feed our gut bacteria. In different terms, prebiotics (soluble fibre like oats, barley, beans, lentils etc) are the food that helps probiotics (good bacteria) grow and proliferate. For women, the recommended fibre intake is 25 grams per day, and for men 38 grams per day[6]. Choose fibre rich foods such as whole grains, fruits and veggies, and plant-based lentils and legumes.
What’s really important to remember is that consuming a specific food or single nutrient in excess, for health, is actually not that healthy. The key is to enjoy a variety of foods, based on your environment, access, mood, and flavour preferences. Putting too much pressure on one single food has the potential to negatively impact your nutrition and mental health.
Unfortunately, there is no super-food cure-all. Instead, think about how you eat versus what you eat to support mental health. If you’re skipping breakfast, for example, you’re allowing your blood sugar to drop, which can lead to irritability, dizziness, and poor concentration. Or if you’re eating in a hurried way, due to hunger or the rush of life, you are more likely to consume a greater portion and feel disappointed, guilty and uncomfortable afterwards. When you can, take the time to sit and enjoy your food you help to reduce stress and aid digestion! Mindful eating is all about being aware of physical hunger and satiety cues and using all your senses in choosing food that is both satisfying and nourishing[7].
The bottom line is that a diet high in whole grains, fruits and veggies, legumes and good fats will help support your mental health as well as your brain health, but shouldn’t be used as a replacement for medication and therapies used to treat mental health disorders.
[1] Seasonal Affective Disorder
[3] What is Grey Matter in the Brain?
[4] The Role of Omega 3 Fatty Acids in Pharmacology
[5] Regulation of Neurotransmitters