What are the effects of junk food? Ultra-processed products include things like soft drinks, packaged snacks, sweetened breakfast cereal and chicken nuggets. They generally contain only trivial amounts of a few micronutrients unless they are fortified, but even then, only a few at higher amounts.

Researchers in the field of nutrition and mental health, and authors of The Better Brain, we recognize that many in our society experience brain hunger, impairing their cognitive function and emotion regulation.

Studies on the Effects of Junk Food

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 per cent of the caloric intake across all ages came from ultra-processed products;
• In the United States 67 per cent of what children aged two to 19 years consumed and 57 per cent of what adults consumed in 2018 were ultra-processed products.

Most of us are aware that dietary intake is a huge issue in physical health because diet quality is associated with chronic health conditions such as obesity, diabetes and cardiovascular disease. The public is less aware of the impact of nutrition on brain health.

Micronutrients and mental health symptoms

Given that our society’s food choices have moved so strongly toward ultra-processed products, we need to learn about the substantial scientific evidence proving 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 is so rarely mentioned in the media that few in the public are familiar with it. A dozen studies from countries like Canada, Spain, Japan 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).

Studies on the Effects of Junk Food on Mental Health

• In a study of about 89,000 people in Japan with 10-15 years of follow-up, the suicide rate in those consuming a whole foods diet was half that of those eating less healthy diets.

• Irritability and unstable mood often characterize depression. 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 one in 10.

• Evidence that irritability, explosive rage and unstable mood can be resolved with improved micronutrient intake comes from studies evaluating micronutrient supplements to treat mental health problems.


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 breaking down and removing metabolic byproducts.
Many studies of multi-nutrient treatments have found 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 even the loss of civility in public discourse.

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