Yes, there seem to be three potential vectors of this.
Simply access to vegetables/healthy foods/giving vitamins is often a pretty clear proxy for higher socio-economic status, and food insecurity is obviously a proxy for low economic status. It could be that other factors of having more resources could contribute to this. This study of 134 kids probably doesn’t have enough participants to effectively control for class. The famous marshmallow experiment found delayed gratification as a toddler was correlated with a robust set of metrics of success. However, a later reanalysis of the original data found that that correlation disappeared when you controlled for class. What looked like a psychological characteristic turned out to be a socio-economic characteristic.
Additionally, the dependent variable is self-assessed. There’s potential for social desirability bias here (though it could go both ways).
Finally, we need to think how this sample was gathered. I didn’t read the full paper, but in general wealthier people are more likely to get screenings, which means that their less severe cases of ADHD are more likely to get diagnosed (and their less severe symptoms could be more likely to be noticed).
Especially with the small effect size, it doesn’t seem like this will be some magical treatment, though it does seem to merit further study.
As part of a larger study, researchers asked parents of 134 kids with ADHD symptoms to complete a detailed questionnaire about the typical foods the children ate, including portion sizes, over a 90-day period.
Another questionnaire asked parents to rate symptoms of inattention – a hallmark of ADHD – in their kids, such as having trouble staying focused, not following instructions, difficulty remembering things, and difficulty regulating emotions.
Results showed that kids who consumed more fruits and vegetables showed less severe symptoms of inattention, said Irene Hatsu,