Mind & Body

Junk Food and the Brain

How modern diets lacking in micronutrients may contribute to angry rhetoric
TIMEDecember 19, 2021

Emotional, nonrational, even explosive remarks in public discourse have escalated in recent years. This is sometimes attributed to social media. But are there other influences altering communication styles?

As researchers in the field of nutrition and mental health, and authors of “The Better Brain,” we recognize that many people in our society experience brain hunger that impairs their cognitive function and emotion regulation.

Ultra-Processed Products

Obviously, we aren’t deficient in macronutrients: North Americans tend to get sufficient protein, fats (though usually not the best fats), and carbohydrates (usually not the good complex carbs). But we are being cheated of micronutrients (minerals and vitamins), particularly those who eat a lot of ultra-processed foods.

Ultra-processed products include things such as soft drinks, packaged snacks, sweetened breakfast cereal, and chicken nuggets. They generally contain only trivial amounts of a few micronutrients unless they are fortified with select vitamins and minerals.

Three published analyses from the 2004 Canadian Community Health Survey and the 2018 U.S. National Health and Nutrition Examination Survey revealed these sobering statistics. In Canada, in 2004, 48 percent of the caloric intake across all ages came from ultra-processed products. The situation was worse in the United States where 67 percent of what children aged 2 to 19 years consumed and 57 percent of what adults consumed in 2018 were ultra-processed products.

Most of us are aware that what we eat is a huge issue in physical health because diet quality is associated with chronic health conditions such as obesity, diabetes, and cardiovascular disease. Fewer people are aware of how nutrition affects brain health.

Micronutrients and Mental Health Symptoms

Given that our society’s food choices have moved so strongly toward ultra-processed products, it has become important more people understand that micronutrient intake influences mental health symptoms, especially irritability, explosive rage, and unstable mood.

The scientific evidence base for this statement is now vast, though it’s so rarely mentioned in the media that few people are familiar with it. A dozen studies from countries such as CanadaSpainJapan, and Australia have shown that people who eat a healthy, whole foods diet have fewer symptoms of depression and anxiety than people who eat a poor diet (mostly ultra-processed products).

Correlational studies cannot prove that nutritional choices are the cause of mental health problems—for that, we turn to some compelling prospective longitudinal studies. In these studies, people with no apparent mental health problems enter the study, are evaluated for their health and dietary patterns, and are then followed over time. Some of the results have been astonishing.

In a study that followed about 89,000 people in Japan for 10 to 15 years, the suicide rate in those consuming a whole foods diet was half that of those eating less healthy diets. This finding may provide an important new direction not yet covered in current suicide prevention programs.

In Canada, another study revealed that how children ate and followed other health guidelines on exercise and screen time predicted whether they would be referred for diagnosis of a mental disorder in the subsequent two years. In this study, the children were aged 10 to 11 years. The findings provide a strong reason for why nutrition education should be one of the first lines of treatment for children facing a mental disorder.

Irritability and unstable mood often characterize depression, so it’s relevant that multiple independent studies have found that teaching people with depression, who were consuming relatively poor diets, how to change to a whole foods Mediterranean-style diet resulted in significant improvements. A Mediterranean-style diet is typically high in whole grains, fruits, vegetables, nuts, legumes, seafood, and unsaturated fats such as olive oil.

In one such study, about one-third of the people who changed to a whole foods diet in addition to their regular treatment found their depression to be in remission after 12 weeks.

The remission rate in the control group using regular treatment but no diet changes was fewer than 1 in 10. The whole foods diet group also reported a cost savings of about 20 percent in their weekly food budget. This final point helps to dispel the myth that eating a diet of ultra-processed products is a way to save money.

Several studies that evaluated using micronutrient supplements to treat mental health problems have provided important evidence that irritability, explosive rage, and unstable mood can be resolved with improved micronutrient intake. Most public awareness is restricted to the ill-fated search for magic dietary bullets. This is exemplified by media reporting that highlights studies focused on a single nutrient at a time. That is a common way to think about causality (for problem X, you need medication Y), but that isn’t how our brains work.

To support brain metabolism, our brains require at least 30 micronutrients to ensure the production of neurotransmitters such as serotonin and dopamine, as well as to break down and remove metabolic byproducts. Many studies have found that eating more micronutrients improved mood regulation and reduced irritability and explosive rage, including in placebo-controlled randomized trials of children with attention deficit hyperactivity disorder and mood dysregulation.

The evidence is clear: A well-nourished population is better able to withstand stress. Hidden brain hunger is one modifiable factor contributing to emotional outbursts, aggression, and quite likely even the loss of civility in public discourse.

 is professor emerita in Cumming School of Medicine at the University of Calgary in Canada, and  is a professor of psychology at the University of Canterbury in New Zealand. This article was first published on The Conversation