Welcome to Nutrition Bites. The no nonsense podcast where you get the truth about food so you can eat what you want, and be healthy. I’m your host Maggie and welcome to Episode 30 of this series! Winter is a season notorious for feeling blue, and with a never-ending barrage of bad world news, the misery this season is really amped up. Which begs the question, can what we eat make us happier? On the menu today, boosting your mood with food.
I’ve never really liked winter. Yes, we have winter sports, cozy snow storms, and cheesy Christmas movies that soothe the soul. But after the holiday lights have dimmed, dreariness rears its cold and grey head. Where I live, January is a month of darkness and minus 20 degree celsius days (that’s -4 fahrenheit), and this combo absolutely kills my will to be healthy. In the summer I wake up early to workout and eat fresh veggies all the time, but come winter, I am the equivalent of Snorlax - opting for McDonald’s breakfast meals because the mere thought of cooking is too exhausting. Now I’m not experiencing depression, that’s a serious clinical diagnosis, but my mood is dampened during this time of year. And while I’m thankful that this is a temporary occurrence, for many people around the world mental illness is a constant battle. One in four North Americans will suffer from a diagnosed mental disorder, with anxiety and depression being the most common. Because of this widespread prevalence, and the seasonal sadness that affects so many, the health and wellness industry is quick to offer up some “au natural” happiness remedies. But, if the answer to depression was to simply eat more oysters I feel like we would have known that by now. It’s true that our diet and mental well-being are connected, but exactly how they are linked isn’t so simple. So let’s find out more.
Back in the 1990s, experimental psychologist Dr. Bonnie Kaplan first linked nutrition with mental health - in particular, using a mix of vitamins and minerals to manage ADHD symptoms in children. And it was this discovery that kicked off the field of nutritional psychology - an area of research dedicated to understanding how the foods we eat affect our mental well-being.
Now this seems like a pretty sensible link on the surface, I mean, when I’ve gone days without fresh fruit and veg my brain just feels foggy, but trying to understand this relationship in detail is hella complicated. Physical health, mental health, and diet are all deeply connected in ways we understand and ways we don’t. This might be a familiar example. Say you are suffering from high stress levels. Your motivation to make healthy food choices is probably lowered, which may result in you ordering a burger and fries for dinner instead of making a homemade salad. Now this dietary choice directly impacts the nutrients you provide your body, and these nutrients influence the status of your physical health. But what we don’t quite understand is how these food choices also biologically impact our mental health. How does that meal of burger and fries change the neurological, hormonal, and immunological pathways responsible for managing our mood? Now one reason why we haven’t answered that question is because we’re still trying to understand mental health in general. I mean, we barely even comprehend the brain! Which is why research in the field of nutritional psychology is pretty broad. So far the focus has been on 3 key themes and their impact on mental health: overall dietary patterns, specific nutrients, and the gut. So let’s dig into each of them.
Thousands of factors can temporarily affect our mood: how restful our sleep was, the results of an NBA game, or how many cute dogs we saw that day. And even though everyone has sad days, where perhaps no adorable puppies were seen, research on mental health focuses less on these temporary experiences and more on people with clinically diagnosed mental disorders like depression. So when it comes to understanding the association of diet and mental health we tend to focus on clinical depression, and here’s what we know so far.
A diet filled with highly refined carbohydrates, like white bread, pasta and rice, and any food or drink packed with added sugar like cookies, muffins, and pop, is the #1 culprit for poor mental health outcomes. I know, I’m the bearer of bad news yet again. But do you think I like being put in this position? Absolutely not! I’m fun most times I swear! But there’s no denying the multiple studies which have found a correlation between a diet high in refined carbs and general poor psychological well being, including depressive symptoms. One theory why this correlation exists is because refined carbs can raise your blood sugar quite rapidly. And a big spike in blood sugar can lead to the release of stress hormones that can cause anxiety and irritability. Another hypothesis is that refined carbs trigger an inflammatory response in the body, which is the release of molecules that accidentally attack healthy cells. Various mental health conditions, including depression, have been linked to a heightened state of inflammation. High calorie meals and foods rich in saturated fat, (think: most fast food and anything fried) also contribute to inflammation. So diets high in a lot of processed foods are also not kind to the mind.
But most ironic of all, is that the dear comfort foods we love to turn to in times of sadness and anxiety, are often composed of refined carbs and saturated fat. Now If you’re someone who choses kale over mac and cheese in times of emotional need, consider yourself very lucky. Because for those of us where that’s not the case, our brains subconsciously encourage us to continue to indulge in these comfort foods when we would actually benefit a lot more from avoiding them. And that’s because of dopamine - a neurotransmitter that makes us feel pleasure in anticipation of AND when we give in to our cravings. And while eating BBQ chips and mint chocolate chip ice cream may provide a temporary mental hug, research suggests that these kinds of foods actually negatively impact our mental health in the day or days after we eat them. Almost trapping us in this cruel cycle of depressed mood. So…can we do anything to help?
Well the answer is both unsurprising and boring. The more fruits and veggies, whole grains, fish, and beans, you eat - the better your brain. And look, I’m even annoyed that I keep repeating myself every episode, but I’m just here to tell you what the science says, and multiple studies have shown that this type of diet is best for our physical and mental health. One study even claims that following this plant-forward and whole-foods focused way of eating may actually decrease the risk of depression by up to 35% compared to those who eat a typical “Western” diet heavy on meat and processed foods. Other studies have found that this type of diet not only decreases depressive symptoms but also increases levels of happiness and mental well-being. But there is a big catch here. Much of this research is based on observation, which can only show correlation not causation. That means we can’t tell if people who are happier or less depressed have that positive mental state because they are eating lots of fruits and veggies, or if eating this type of diet is a result of already having a positive mental health status. It’s like chicken and the egg but make it fruit and the brain. That’s why clinical trials are really important to help start answering these questions.
So far, there hasn’t been much clinical research done, it’s a new field after all, but in two recent studies out of Australia, depressed adults who adjusted their diets to eat less processed food and consume more produce, fish and legumes, significantly improved their symptoms compared to a group that did not change their diet. Amazingly, in one of those studies almost 1/3 of the participants in the diet group were no longer classified as depressed by the end of the 3 month program. And this benefit occurred even though the participants did not lose any weight! Which is so important for establishing that direct relationship between diet and mental health, rather than feeling mentally better because of changes in your physique. Clinical research in other areas also support this plenty of plants way of eating. For example, consuming complex carbs (which are found in whole grains and produce), helps stabilise our blood sugar levels - keeping irritability at bay and improving mood. Aka preventing those hangry mood swings from refined carbohydrates. But while this is all very promising research, making big dietary changes is really really hard. Like, even trying to eat one more vegetable a day can feel as exhausting as participating in a virtual drinks social. Sidebar: I’m so glad we collectively abandoned those. So instead of changing our whole diet, can we focus on a few individual nutrients instead?
One of the most common micronutrients to pop up in a “eat your way out of depression” article are the omega-3s, a group of essential fatty acid found in flaxseed, chia seeds, and fatty fish, which are very important for heart and brain health. Omega-3s are known to be neuroprotective, which is why there is a lot of research on how they can potentially prevent diseases like dementia. And it’s this property that makes them a nutrient of interest for mental health research. In fact, the second result from googling “Omega 3s” is an article that outright states this nutrient can fight depression and anxiety. But this is a big stretch. Most research thus far on omega-3 supplements and mental health has found no effect, and the studies that do show a positive association often come with a lot of caveats. Like the clinical trial that showed omega-3 supplements improved symptoms in depressed adolescents, but only if they already had a family history of depression.
And it’s a similar story with the B Vitamins. Vitamin B6, Vitamin B9 (aka folate), and Vitamin B12 are all commonly linked to mood. That’s because a deficiency in these nutrients is associated with elevated levels of a biomarker linked to depression. And while there are many studies that show people deficient in any of these nutrients have a heightened risk of depression, there’s no concrete evidence that shows supplementation improves depressive symptoms. Even in a recent, large review of research, covering over 2000 subjects, only half of the trials showed a positive effect of B Vitamin supplements on mood. And more specifically , those positive effects were only related to reduced stress, not depression or anxiety.
And to be honest, these kinds of results are really common in nutritional research. Vitamins, minerals, fatty acids and all the other micronutrients work synergistically in our body. Isolating just one of them to resolve a biologically complex condition like depression is a pretty pathetic analysis of how intricate our bodies and brains are. Which is why changes to our overall diet, that helps to provide an abundance of many micronutrients, is the best bet to improve our mental health.
And implementing those dietary changes of more whole plants and less sugary processed foods, are also crucial for supporting our gut - the third, and final, focus of nutritional psychology. I’ve talked about the gut-brain-axis before, but in short, it describes how our nervous system, including the brain, and the gut communicate through nerve cells and chemicals that our gut bacteria release. The connection between mental health and our gut isn’t particularly surprising because some mental health conditions, like anxiety, are often linked to digestive issues like Irritable Bowel Syndrome. Multiple studies have also found that people with clinical depression have abnormal gut microbes - either fewer of the “good” bacteria or more of the “bad” ones.
And the link gets even deeper. Over 90% of our body’s serotonin, the famous “feel good” hormone, is actually produced in the gastrointestinal tract. This neurotransmitter helps regulate our mood and low levels are associated with depression. Incredibly, the production of serotonin is also thought to be partially controlled by, you guessed it, those feisty little bacteria. But if you are clinically depressed and taking medication, don’t go chugging kombucha just yet to improve your microbiome. Some antidepressants are known to negatively interact with things like fermented foods, so it’s best to talk to your doctor before funking up your diet with kimchi and the booch. That’s a great band name. That said, eating plants is a safe way to support your gut so don’t be afraid to climb aboard the fibre train.
And that’s kind of the main lesson for this whole episode. Although the field of nutritional psychology is still evolving, so far we’ve found that a diet high in plants, with few animal products and processed foods, improves your mental health in many different ways. But don’t take that as a free pass to tell someone with depression to try “eating carrots”. Not only is that laughly offensive, but the singular veggie to happiness pipeline does not exist. Despite what WebMD has to say, not one specific food or nutrient has been scientifically classified as a “mood booster”. So be cautious of the “Top 10 foods I eat everyday to be happy” buzzfeed articles that may sprinkle in scientific terminology to convince you a daily banana will keep the therapist at bay.
Overall just remember that there’s no catchall food or nutrient for individual happiness. Yes, ordering a bagel with smoked salmon, high in omega-3s, is delicious, but it won’t alleviate your emotional turmoil - at least not in the long-term. And even the recommended diet of plenty of plants, whole grains, fish and legumes is neither an immediate nor guaranteed remedy for mental disorders. This is just an observation that we’re looking to better understand. But that said, this type of diet is still amazing for our physical health. So whether or not eating this way actually decreases depressive symptoms or increases happiness, we do know that your heart, liver, and stomach are all going to be better off if you choose that salad over mac and cheese. At least most of the time. Some days, you just need a cheesey mental hug and that’s ok too.
That’s been the bite for today. Stay hungry.