The Washington Post reported last week that perhaps one in five American children is diagnosed with a mental disorder each year, and the rate is only increasing. Citing new data from the Centers for Disease Control (CDC), The Post suggested that the increase in mental disorders is being driven by increased awareness, poverty, and environmental factors.
These are all reasonable culprits, but the paper missed a potentially serious cause of mental health problems in its report: Poor diet. We know that unhealthy eating makes us fat and sick, so it wouldn't be unreasonable to ask if all the awful food we eat is also partially responsible for the increase in mental disorders we're seeing. Judging by the evidence, the answer is yes.
The Post came close to this conclusion by referencing poverty as a driver of mental disorders. Of course one of the consequences of extreme poverty is malnutrition, and malnutrition can stunt a child's intellectual development, according to a study published in Nature. A more recent study conducted by researchers at the University of Southern California (USC) found that “Poor nutrition, characterized by zinc, iron, vitamin B and protein deficiencies, leads to low IQ, which leads to later antisocial behavior … These are all nutrients linked to brain development." The data on the relationship between malnutrition and intelligence go on and on, but the point is pretty clear: The human brain doesn't do well on a poor diet.
In the United States, the problem isn't a lack of access to healthy food, like it is where the above research was conducted. Most of us could eat healthier if we wanted to, but we just don't want to. It's a different form of malnutrition, though it affects our mental health similarly to how starvation would. The Post reported that the conditions most likely to affect American children include ADHD, depression, and autism, which often manifest as the behavioral problems described by the USC researchers. Furthermore, there is some research that suggests these conditions are exacerbated by poor diet, and may even have dietary causes in many cases.
Spending the afternoon on pubmed searching for that evidence may not sound like fun, so here's a few examples to get you started. A 2009 study found that people with ADHD consumed more omega-6 polyunsaturated fats than the controls in the study, and most Americans eat plenty of them, too. Research has also linked depression and autism to diets low in cholesterol, which Americans dutifully avoided for decades because we were told it would cause heart disease, though it doesn't.
Right around this time last year, as the media was promoting the latest “red meat will make you dumb” study, PolicyMic published this thoughtful refutation of the exaggerated news stories about the research. Particularly relevant to this discussion is a Journal of Nutrition article referenced in that piece which concluded that a certain amount of saturated fat is necessary for children because it "... facilitate[s] maturation of the central nervous system, including visual development and intelligence."
Sugar also deserves some of the blame, probably even more than our phobia of saturated fat. It's becoming more and more fashionable to blame sugar for the obesity epidemic, but less attention is paid to how it affects our brains, though we have a good idea how it does. Sugar consumption, even in small quantities, has been linked to behavioral problems in children, and violent behavior as they grow. Research has also linked insulin resistance, caused by eating too much sugar, to Depression and ADHD, among other mood disorders.
When journalists suggests that really complex public health problems have simple solutions, an alarm should go off in your head, because what you're reading is probably bullshit. So let me clarify two things very quickly. Avoiding sugar isn't a miracle cure for depression, and there isn't a corporate conspiracy lead by Big Food to handicap our kids. Nonetheless, there's pretty good evidence linking unhealthy eating to mental disorders, and perhaps that's a relationship we ought to pay more attention to. Or as one of the USC researchers put it, maybe “parents [should] be thinking more about what kids are eating?"