Episode 11: Food for Thought: The Surprising Link Between Diet and Mental Health
Podcast Transcript
Dr. Kuhathasan: Welcome back to another episode of the CAN-BIND podcast. I’m Nirushi Kuhathasan, your host for today, and we’re about to explore something that plays a bigger role in our mental health than we might think. In this episode, we explore a relationship that’s as old as humanity, but has only recently found its place in scientific study: the diet and mental health connection.
Modern living may bring convenience at the cost of wellness, but we often overlook one of the most profound connections in human health. Food and mood—two things we often think about separately. But what if they’re more connected than we realize? In recent years, we’ve seen a growing body of research linking diet with mental health conditions like depression, anxiety, and even more complex disorders such as bipolar disorder. But how deep is this connection? How much do we really know about the foods that nourish our brains?
To explore this fascinating link between diet and mental health, we turn to the work of Dr. Fabiano Gomes, a clinician-scientist and psychiatrist at McMaster University, and recipient of the prestigious Brain and Behavior Research Foundation Young Investigator Award. He’s also a member of the early and mid-career committee of the International Society for Bipolar Disorders. Dr. Gomes has been at the forefront of understanding how our nutritional habits are tied to mental health conditions. He explains that the idea of a connection between food and mental health is not a new one, tracing this awareness back to historical observations.
Dr. Gomes: “This is a really interesting topic, right? It’s been there forever, right? So at first people would notice that certain vitamin deficiencies could be related to neurological and mental symptoms. People would go traveling across the oceans, right, in the discoveries and they notice that that would be a thing. So we do know that your nutritional status has a lot to do with brain-based conditions, including psychiatric conditions.”
Dr. Kuhathasan: In other words, the nutrients—or lack thereof—that we take in have always had a profound impact on how our brains function. What we might not have fully appreciated until more recent studies is just how strong that connection can be. In fact, the quality of our diet, particularly in today’s Western world, might be contributing to the growing rates of mental health disorders. As Dr. Gomes describes, it’s not just about vitamins and deficiencies, but about the very nature of the processed foods we consume.
Dr. Gomes: “In recent years, a lot of studies they have tried to understand if there is a relationship between what we call the Western diet— it’s usually diet that it’s rich in highly processed foods junk foods and foods that are not more fresh… vegetables, fruits, even meat — with more traditional diets, right… such as the Mediterranean diet. People in western countries, especially the US and North America, they have much higher rates of obesity, and also a lot of psychosocial and mental conditions arising in those specific populations compared with others.”
Dr. Kuhathasan: So the shift to a diet heavy in processed foods isn’t just a nutritional issue—it’s contributing to mental health crises. These foods are cheap and convenient, but they come at a cost. And it’s not just obesity we should be concerned about; the mental health component is becoming clearer with every new study.
Dr. Gomes highlights that these dietary patterns have been linked to conditions like anxiety and depression, with mounting evidence across all age groups that the quality of diet is a key factor in mental health outcomes.
Dr. Gomes: “Now we have compelling evidence that across all age groups, the quality of the diet is related to more or less risk of different types of mental health conditions— from anxiety, to depression, to substance use”.
Dr. Kuhathasan: He also touched on Attention Deficit Hyperactivity Disorder, or ADHD, noting that while there’s less evidence to suggest diet as a direct cause, it can certainly make symptoms worse.
Dr. Gomes: “ADHD we have less of that… but it seems like the quality of the diet in ADHD children also can make it even worse, right? So less evidence to like increasing the incidence of a causal factor but definitely to aggravating the symptoms.”
Dr. Kuhathasan: This brings up an important point: While diet alone might not cause certain disorders, it seems it does play a role in the severity of the symptoms people experience. And when it comes to depression and anxiety, Dr. Gomes explains that we have even stronger evidence pointing to diet as a potential cause.
Dr. Gomes: “We have some longitudinal studies showing even evidence for a causal effect in increasing the risk of developing both anxiety and depression.”
Dr. Kuhathasan: But how exactly does something we eat affect our brain? Dr. Gomes talks about the critical role the gut-brain axis plays in this interaction.
Dr. Gomes: “One of the main candidates of how to mediate this process is what we call the gut-brain axis, right? It’s mostly related to our microbiota. So it’s the type of bacteria that we have and we know that depending on the type of diet that you are exposed to, you can have changes in the microbiota. And depending on the type of bacteria that you have in your gut, you can have different outcomes. So some of the bacteria, they may produce more of anti- or pro-inflammatory substances. So you can have an increased state of inflammation for example. You can have what they call ‘leaky gut,’ where you have some of the bacteria is translocated from the gut to the bloodstream. It’s possible that other elements, like the quality of the diet itself, the number of carbohydrates, the type of proteins, amino acids and micronutrients, would also be different.”
Dr. Kuhathasan: In other words, what happens in your gut can influence what happens in your brain. The gut-brain axis is a two-way street, meaning that stress or mental health issues can also affect your gut health, creating a cycle that’s hard to break.
And processed foods? They’re not doing us any favours in this department. As Dr. Gomes explains, it’s not just about what you’re eating, but also how that food is impacting your body’s inflammation levels and nutrient absorption, both of which have a direct link to your brain function.
For those of us from diverse ethnic backgrounds, there’s also the question of whether the same diets benefit everyone. For instance, we talk a lot about the Mediterranean diet being healthier than others. Dr. Gomes acknowledges that while the Mediterranean diet is often recommended, it might not be the best fit for everyone.
Dr. Gomes: “Most studies that criticize the Mediterranean diet… is that it’s possible that the main benefit…it’s when you have that specific group that evolved having that diet. When I say that the Mediterranean diet has more evidence, it’s more like they had studies. For example, people with hypertension and then when you use a specific diets such as the DASH diet or the Mediterranean diet, because it’s a more balanced diet and you don’t have that much processed foods, people would show some benefits. But some other studies show that whatever diet that it’s the traditional diet for that specific population, is the best diet. So for example for like Asian people right, depending on where they are, they might drink a lot of soy products right? And that’s their traditional diet. If you stick to that traditional diet, it will be good for you. The thing is we have had introduction of this highly processed foods, a lot of additives and sugary drinks, all around the world, so you’re changing the most traditional diets. But if you’re eating foods that are natural foods, that are fresh and they’re not highly processed, it would be the recipe to go to have better health outcomes and also to prevent the incidence of some mental conditions.”
Dr. Kuhathasan: The message here is clear: it’s not just about adopting specific diets as the gold standard. We might even consider returning to the traditional diets that our ancestors thrived on, but what’s most important is avoiding processed foods and sticking to natural, fresh ingredients.
But what does this mean when it comes to supplements? So many of us reach for supplements that promise to provide all the nutrients we need. Well, Dr. Gomes urges caution.
Dr. Gomes: “Of course if you have specific deficiencies… some vitamins we have some specific directions of how much you should take daily and if you’re not having that, you need some supplements right? But usually if you are on a diet that you’re eating fresh food, fresh vegetables, you will have most of them. So as a general rule, we would say that most of the time you don’t need to if you have a decent diet or diet that is within most standards. If you have a specific deficiency then you should supplement.”
Dr. Kuhathasan: So we know diet plays a powerful role in our mental health, but what exactly can a healthy diet do for our brains?
Dr. Gomes: “Some interventions that helped to improve the quality of the diet, they were successful as an adjunctive treatment to improve mood. So just by telling people which type of foods they should avoid and which type of foods they should eat even without prescribing a specific diet, could help. There’s one specific diet that we’ve been studying and there’s a lot of research currently on: it’s the ketogenic diet.”
Dr. Kuhathasan: The ketogenic diet is based on a low-carb, high-fat model, where the body shifts from using glucose as its primary energy source to using ketone bodies derived from fat. This metabolic shift could have a profound impact on brain function and can be used to treat a number of brain-based illnesses and conditions.
Dr. Gomes: “So the ketogenic diet as a medical and metabolic treatment has been used for over 100 years in the treatment of treatment-resistant epilepsy, right? So 100 years ago kids with epilepsy, there would be no treatment. And then they noticed that when they were fed a diet that was mostly comprised of proteins and fats, that would have an anti-seizure, anticonvulsant effect.
Because of the low carbohydrate content you will have a shift in using mostly glucose as the main energy source to using Ketone bodies. The Ketone bodies they’re derived mostly from fat that can be eaten from what you’re ingesting or the fat that you’ll be burning out of your own fat tissue because you are restricting calories from carbohydrates. So it’s like as you were on a fasting. It’s not the same thing, but when you have a drop in your intake of glucose your body would say okay I need to save some of the glucose for my brain and some more vital organs that need that and I will start using ketones as the main source of energy. But you can also use ketones in the brain. And they are a really effective energy source. So when you have this shift of using glucose to Ketone bodies at some point it seems like the energy production is much more effective.
The theory is that you have a lot of different processes that are changed in the brain. You might use more effectively this energy and brain processes are better and you improve. And you can even have this change in the seizure threshold that helps with seizures as an anti-seizure medication. In your body you have a number of different changes as well, those Ketone bodies they are metabolized and some of their metabolites you can measure in the blood and in the urine so you can monitor the level of ketosis you’re having. In the beginning you can have even some side effects. Some people would say that they are a bit more tired, they have less energy, brain fog, but usually after a couple of weeks if you persist on that your body gets used to this ketotic state and you could have this improvement sometimes in mood energy and eventually even cognition right. So this is something that we are really looking into. And when they research people with treatment resistant epilepsy and looked into their quality of life and depression, they improved. So it’s possible and now there’s a lot of different studies going on trying to see if we’ll be finding the same good results we see in epilepsy.”
Dr. Kuhathasan: But, as Dr. Gomes emphasizes, it’s not just about removing carbs or going on any trendy diet. The ketogenic diet requires careful management and supervision, especially for those with mental health conditions. While the diet shows promise, it’s not a cure-all, and much more research is needed.
At the heart of Dr. Gomes’ work is a balanced approach. There is no “one-size-fits-all” solution, and the right dietary choices depend on an individual’s unique needs and conditions.
Dr. Gomes: “A lot of people that advocate in this space, they think that it’s the… the main villain is the glucose and it could be. And when we are using the ketogenic diet you change and people can even have a lot of improvements in their glucose levels and even diabetes, right. But again we don’t have enough evidence yet that just by using the ketogenic diet you reverse, for example, diabetes, right? It seems like it can be an important treatment and there are studies going on and we have information about that.
Outside of, I mean, really cutting edge research and really valid research, there’s a lot of people just trying to sell whatever out there, right? That’s why, I mean, I’m a bit skeptical in the way of just saying I think this can be a really… seems to be a really powerful treatment that will likely work for some people that might be able to use the diet with more treatment resistant cases. And other people that do well on other treatments, they might just stick to a specific treatment.”
Dr. Kuhathasan: In a world where quick fixes and fad diets are marketed as the answer to all our health problems, Dr. Gomes’ insights remind us that the connection between diet and mental health is complex and deeply personal. Whether it’s sticking to traditional diets, avoiding processed foods, or exploring new dietary treatments like the ketogenic diet, the key is to approach these changes with care and evidence-backed guidance.
Dr. Gomes: “There’s no one size fits all right. Especially related to mental health but it seems like this could be another tool if we get the data and the data is positive to help people that have… I mean a lot of treatments have failed on them right. So I think it’s important to have research on safety and trying to understand who this would work for”.
Dr. Kuhathasan: As Dr. Gomes would say, it’s about using the right tools to optimize brain function and improve mental health outcomes for those who need it most.
So the connection between diet and mental health is proving to be a promising area of research. We now know that changes to our diet can have a greater impact on our mental well-being than we once realized. It’s a powerful reminder of how interconnected our physical and mental health truly are.
With that in mind, if you’re interested in learning more about depression research and the work we’re doing, be sure to visit our website at www.canbind.ca
Thank you for tuning in, and until next time, stay curious!