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Nutrition and Mental Health: You Are What You Eat

Posted on : August 17, 2022 by Hardy Nutritionals® No Comments

Does nutrition have a correlation to mental health? Throughout a three-part lecture series, psychologists and nutrition experts Bonnie J. Kaplan, Ph.D., and Julie Rucklidge, Ph.D., seek to explore the history of research on nutrition and mental health around the world and how supplementing with micronutrients may create change from the ground up. 

The second part of this series features Dr. Bonnie J. Kaplan, Professor Emerita in the Cumming School of Medicine at the University of Calgary, in Calgary, Alberta, Canada, and author of the book The Better Brain. Weeding through 2,600 years of folklore and modern science, Kaplan catches us up on the history of population health studies, the differences between Mediterranean and Western diets, and finally, how healthy nutrition can impact our mental health even in the face of catastrophe. 

To watch the entire free lecture series, click here!

Is Your Diet Depressing You?


In population health studies, Kaplan points out that almost all the research has been in the past five to ten years. Before that, research was focused on overall dietary intake, such as a study published on the consumption of fish – in which researchers found that those who ate a healthier diet with fish experienced less negative feelings than those who did not. But in general, the effect of overall healthy eating hadn’t been scrutinized until the last decade. 

That’s what Dr. Bonnie Kaplan and her colleagues are here to change. 

Throughout the lecture, Dr. Kaplan points out studies that look into the Mediterranean diet vs. the Western diet, which consists of processed foods such as unhealthy meats, sugary snacks, and soda, by comparison. This is sometimes referred to as SAD, or Standard American Diet. 

What’s great about the Mediterranean diet is consumers ingest more vitamins, minerals, and good fats without increasing calories. People who eat this way primarily have a lower rate of mood and anxiety symptoms and inflammatory biomarkers. 

In an Australian study titled “Associations between diet quality and depressed mood in adolescents: results from the Australian Neighbourhoods Study,” 7000 adolescents between the ages of 10-14 were assessed for mood symptoms in relation to their diet. The healthy participants ate a daily breakfast and had fruits, veggies, dairy, and more. The unhealthy participants ate processed foods, sugary drinks, donuts and cakes, and so forth. 

Scientists observed an inverse relationship between diet and mood. Those with poorer diets had more issues with mood, and those with better diets had fewer mood-related issues.

In one Canadian study called “Diet quality and feelings of worry, sadness, unhappiness,” published in 2013, 6,500 children in fifth grade were surveyed about their diet quality and associated feelings of worry, sadness, and unhappiness. Researchers found that for every 10% increase in diet quality score, there was a 10% decrease of those negative feelings. 

Also of note, this was the youngest population studied in this field. The study demonstrated that young children are able to detect and report their feelings and that there is a relationship between their moods and what they eat. If kids understand what foods make them feel good, this could impact their physical and mental health trajectory for the rest of their lives. 

This begs the question,  Are we feeling bad because we’re eating bad, or are we eating bad as a result of our feelings? We’ve all heard of “eating our feelings” before. 

Dr. Kaplan explains this breaks down to being a question of reverse causality. “The solution is to recruit people when they don’t have any symptoms of mood and anxiety and track them to see how their eating is associated with mood and anxiety,” she lectures. 

A UK paper sought to answer this with a study called “Dietary pattern and depressive symptoms in middle age.” During this, researchers studied 3500 middle-aged people in the London area.

They looked at dietary quality and separated them into two categories – whether they were eating mostly whole foods or processed foods – and measured mood with a scale called the CES-D (The center for epidemiologic studies depression). After following the participants for five years, the research question became “is there a correlation between later occurrence of depression and their dietary pattern?” 

People who were eating whole foods by and large had a lower incidence of depression compared to those who ate a Western diet. 


Another research paper out of Spain titled “Fast food and commercial baked goods consumption and the risk of depression,” studied 16,000 former students and professors from the University of Navarra for years. When they entered the study, they showed no signs of mood disorder or anxiety. They were given a questionnaire asking how often they ate commercial baked goods like donuts, croissants, and muffins, and how often they ate hamburgers, sausage, and pizza. Researchers split participants into two groups: those with an unhealthy diet and those with a healthy one.

Over the six years, on average, the people in the highest third for consuming processed foods and fast foods had a significantly greater risk for the diagnosis of depression than those in the middle or lowest third. 

“So how do we interpret this? Am I saying that muffins cause depression?” Kaplan asks. “This isn’t a story about gluten; it’s a story about food choices. With every bite that we eat, we are making a choice. When we say eat the rainbow, we’re not talking about the donuts.”

Still, Dr. Kaplan points out that we must be careful when interpreting this data. 

Using a study on soft drink consumption as an example, researchers discovered that the children who consumed the most soda also had the most hyperactivity. Kaplan argues that this doesn’t mean soda directly correlates to hyperactivity and mood disorders but that the children drinking the most soda also eat the most processed diets. We have to look at a pattern of dietary consumption overall, not just small pieces. 

Are Nutrients the Game Changer We Need?

Throughout the lecture, Kaplan cites proof that nutrition truly impacts mental health. But what if our food isn’t a high enough source of micronutrients due to soil depletion or just a lack of access to a well-rounded diet, and not everyone is getting the vitamins and minerals their brains need to perform optimally? Supplementing properly could change that.

In one of many studies Dr. Kaplan carried out in her lab, she and her team looked at 97 community-living adults who had been diagnosed with mood disorders. For a concrete baseline, they re-diagnosed the participants with structured clinical interviews. Then, they asked participants to track everything they ate for three days. After that, a computer program would analyze the food for the presence of different vitamins and minerals, including zinc, iron, b12, thiamin, phosphorus, magnesium, and calcium. 

To Kaplan’s surprise, the presence of these vitamins and minerals mattered greatly even in such a small snapshot of a high-functioning subset of people. 

In a study by the Medical University of Vienna dubbed the “Prevention of psychosis study,” researchers studied 13-25-year-olds who met established criteria for high-risk psychosis, involving family history, early onset symptoms, etc. 

Eighty-one people were arranged to either receive omega-3s or a placebo for 12 weeks. Then, they were monitored for 12 months. The question was whether this intervention will help participants avoid having a psychotic episode. The answer was yes. About 5% of their sample had a psychotic episode, and over 28% on the placebo experienced psychosis. 

So what’s the message? It’s important to tell everyone to eat better. It’s hard to change how people eat, but we must educate them. When people understand their food choice affects their brain function that day, they seem to support the greater understanding. 

Nutrients After Catastrophe

It’s well researched that a healthy diet can lead to a healthy brain. But what about in catastrophic circumstances, such as natural and unnatural disasters? 

In 2010, Dr. Julia Rucklidge accidentally found herself in a situation where she was able to test the impact of regularly taking broad-spectrum micronutrients on trauma victims. That year, the community of Canterbury and Christchurch,  New Zealand, unexpectedly experienced a severe earthquake with many aftershocks. 

In the aftermath, Rucklidge found 33 adults who had been taking the micronutrient in the area – 16 of which were still using the broad spectrum micronutrients and 17 who had done so previously but were no longer taking them. All the participants reported high levels of depression, anxiety, and stress. But those taking the micronutrients were significantly less stressed at two weeks.


In February 2011, another massive earthquake hit, leaving thousands injured and almost 200 dead. Once again, Rucklidge and her team studied the effects micronutrients would play on those in a post-traumatic situation.  Of the 91 participating adults, her team gave a third of them a B-complex formula, a third received a low dose of the micronutrient blend, and a third received a high dose of the micronutrient blend, plus a control group. 

The control group got more anxious and stressed from baseline over the next four weeks. The B-complex group had improvement in overall feelings, the most successful being for depression. The low dose group actually had the most improvement, with anxiety the best followed by stress and depression, and the high dose significantly improved on all three as well. 

Many people in the nearby area may have met the criteria for PTSD, so the researchers dove into that as well. At the time, the people in the control group didn’t change; about 50% of them met the criteria for PTSD at baseline. All three micronutrient users, however, had a severe drop in PTSD scores over the four weeks, from 50% to just under 20%. 

What about a year later? The control group experienced a slight change in health over time. The group that received micronutrients experienced a significant improvement in their mental health.

So, Does Nutrition Affect Mental Health? 

Throughout her lecture, Dr. Kaplan draws a clear path to a healthy, whole diet making a huge difference in mental health. And where nutrition falls short, micronutrients can pick up the pieces. Overall, Kaplan stresses the importance of better food education. 

“We have to feed people with nutritious food to nurture mental health just as much as we want to nurture physical health. If we spent $160 in the US per person per year on food, no one on the planet would be hungry. Instead, we’re spending it on other things,” she emphasizes. 

Are you interested in learning more? You can watch the whole three-part lecture series for free by clicking here

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