Nutritional Psychiatry: the link between diet & mental health
Can what we eat impact our emotional and mental wellbeing? According to studies in nutritional psychiatry, a relatively new scientific field examining the connection between food and mood, the answer is an emphatic yes. Read on to learn what this paradigm shift means, and how to implement brain- and mood-boosting food choices.
It’s a widely accepted fact that our dietary choices play a considerable role in our physical health and wellbeing. We know, for instance, that a diet high in saturated fats and cholesterol can lead to obesity, heart disease, and/or diabetes, while a Mediterranean diet rich in fruit, vegetables, and unsaturated “healthy” fats can improve cardiovascular health. The physical consequences of our dietary choices can make themselves apparent within minutes or hours, be it heartburn from acidic foods or a stomach-ache from overindulging.
WHAT IS NUTRITIONAL PSYCHIATRY?
In recent years, scientists and mainstream society have come to terms with the fact that our diet can affect our mental health too, manifesting itself in our mood, our cognitive ability, and even our memory. The nascent field of nutritional psychiatry digs into precisely these issues, studying the gut-brain connection and examining how strategic changes in our nutritional choices can have profound effects on our mental health and stability.
THE GUT-BRAIN AXIS
Around 90% of our serotonin (the neurotransmitter which regulates our moods, sleep, and appetite) is produced in the gastrointestinal (GI) tract. Within the GI tract, billions of “good” bacteria block off toxins and “bad” bacteria, enable sufficient nutrient absorption, and activate the neural pathways between the gut and the brain. Ensuring that sufficient “good” bacteria are present within the gut can help prevent asthma, obesity, and diabetes - and some mental disorders, too!
Felica Jacka, an Australian researcher, is at the forefront of nutritional psychiatry. Her 2010 PhD study found that women with diets high in vegetables, fruit, and fish were less likely to suffer from anxiety or depression than those with diets high in processed foods such as refined carbohydrates and sugars. Processed foods can increase inflammation, which triggers oxidative stress, which in turn triggers distress signals in the brain that can potentially cause anxiety and depression.
The pool of evidence is growing: within the past decade, numerous studies have found similar links, for instance a 2013 study which found that the Mediterranean diet could reduce the risk of depression and cognitive impairment. Correlations, of course, do not prove causality, but the links are worth exploring further.
A “healthy” diet differs from culture to culture, but the general consensus encourages eating more plants, fish, and unrefined grains and less meat, sugar, and processed foods – regardless of geography. The Mediterranean and Japanese diets are often favoured for their reliance on fruits, vegetables, seafood, and healthy oils.
FOOD FOR MOOD
We have bad news for anyone who relies on ice cream and cookies when they’re stressed. Studies show that while sweets trigger a release of the “happy hormone” serotonin, satisfying us in the moment, that the ensuing crash can cause a stress response in the body and increase our “stress hormone” levels (cortisol). Essentially, this means that turning to sugary foods for stress-relief actually fuels the stress, with the drastic crashes in blood sugar causing equally drastic mood swings. Not to mention the sleepless nights and morning-after brain fog experienced after a “sugar high”.
Eating nourishing foods full of micronutrients, vitamins, and mesonutrients (high in antioxidants), on the other hand, protects the brain from cell-damaging oxidative stress.
So, if ice cream is not the answer, then what is? What should we eat to optimize our mood?
A 2018 study investigated which foods were the most nutrient-dense sources of the key nutrients scientifically proven to prevent or improve depressive disorders. Each food was assigned an Antidepressant Food Score (AFS) based upon their nutrient density. Turns out your mother had a point when she told you to eat your greens: vegetables as an overall category had the highest mean AFS!
Keep scrolling to see which foods topped the list.
A semi-aquatic plant native to Europe and Asia, Watercress reigns with an AFS score of 127%. It has a slightly peppery flavor and is packed with vitamin K, vitamin C, and vitamin A. Use it as a base in a salad, or make a soup.
Oysters are no longer just an indulgent treat for your next celebration: with an AFS score of 56%, they are a great source of zinc, vitamin D, vitamin C, and calcium.
3. Beet and Turnip Greens
The next time you buy beetroots or turnips, be sure to keep the leafy tops. Prepare them as you would kale or spinach, sautéed, steamed, or as greens in a salad. AFS score: 76%-93%.
Trusty spinach is a frontrunner with its AFS score of 97%. Brimming with folate and tryptophan (both of which stimulate serotonin levels), it’s the ideal side dish to any meal.
Grapefruit’s exotic cousin is considerably larger, slightly pinker, and much sweeter. Eat it on its own as a fruit, or prepare it as a spicy Thai salad. AFS score: 69%. Keep in mind, however, that pomelo (like grapefruit) contains a substance which can interfere with certain medicines.
Probiotics and Prebiotics
A 2017 systematic review of existing research found positive results regarding the effects of probiotics on mood and cognition, indicating that our reactions to stress and anxiety is closely tied to the state of our microbiome. Probiotic foods (such as kimchi, kombucha, and miso and yogurt) and prebiotic foods (such as garlic, artichokes, and onions) help maintain a level of “good” bacteria in the gut, thereby helping reduce anxiety levels and perception of stress.
Supplements with concentrated “good” bacteria are also available, and can improve overall wellbeing, immunity, and digestion. Clinical trials suggest that the Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 strains specifically and positively support mood and emotional well-being.
SHOULD YOU SEE A NUTRITIONAL PSYCHIATRIST?
Dietary adjustments alone will not solve deep-rooted mental health condition. A nutritional psychiatrist will examine each patient individually and set up a plan on a case by case basis: the treatment route might include dietary changes, psychotherapy and conventional medication. However, as Jacka notes, diet is - to a certain degree - one of the risk factors related to mental health that we have the power to change (unlike genetics, poverty, trauma, and other environmental factors). Incorporating more nutrient-dense foods and cutting down on processed and sugar-laden foods may not be a magic bullet, but given the strong scientific evidence, it’s certainly worth a try.