Kids who eat fish at least once a week sleep better and have IQ scores that are 4 points higher, on average, than those who eat fish less frequently or not at all, a new study shows.
Previous studies showed a relationship between omega-3s, the fatty acids in many types of fish, and improved intelligence, as well as omega-3s and better sleep. But researchers hadn’t connected all three before.
The findings reveal sleep as a possible mediating pathway, the potential missing link between fish and intelligence.
“This area of research is not well-developed. It’s emerging,” says Jianghong Liu, associate professor of nursing and public health at the University of Pennsylvania and lead author of the study, which appears in Scientific Reports. “Here we look at omega-3s coming from our food instead of from supplements.”
For the work, a cohort of 541 9- to 11-year-olds in China, 54 percent boys and 46 percent girls, completed a questionnaire about how often they ate fish in the past month, with options ranging from “never” to “at least once per week.”
Children also took the Chinese version of an IQ test called the Wechsler Intelligence Scale for Children-Revised, which examines verbal and non-verbal skills such as vocabulary and coding.
Their parents then answered questions about sleep quality using the standardized Children Sleep Habits Questionnaire, which included topics such as sleep duration and frequency of night waking or daytime sleepiness. Finally, the researchers controlled for demographic information, including parental education, occupation, and marital status, as well as the number of children in the home.
The findings show that children who reported eating fish weekly scored 4.8 points higher on the IQ exams than those who said they “seldom” or “never” consumed fish. Those whose meals sometimes included fish scored 3.3 points higher. Further, increased fish consumption was linked to fewer disturbances of sleep, which the researchers say indicates better overall sleep quality.
“Lack of sleep is associated with antisocial behavior; poor cognition is associated with antisocial behavior,” says Adrian Raine, a professor with appointments in the School of Arts and Sciences and the Perelman School of Medicine. “We have found that omega-3 supplements reduce antisocial behavior, so it’s not too surprising that fish is behind this.”
Jennifer Pinto-Martin, professor of nursing and of epidemiology and also executive director of the Center for Public Health Initiatives, sees strong potential for the implications of this research.
“It adds to the growing body of evidence showing that fish consumption has really positive health benefits and should be something more heavily advertised and promoted,” she says. “Children should be introduced to it early on.” That could be as young as 10 months, as long as the fish has no bones and has been finely chopped, but should start by around age 2.
“Introducing the taste early makes it more palatable,” Pinto-Martin says. “It really has to be a concerted effort, especially in a culture where fish is not as commonly served or smelled. Children are sensitive to smell. If they’re not used to it, they may shy away from it.”
Given the young age of the study group, researchers chose not to analyze the details participants reported about the types of fish consumed, though they plan to do so for work on an older cohort in the future. They also want to add to this current observational study to establish, through randomized controlled trials, that eating fish can lead to better sleep, better school performance and other real-life, practical outcomes.
For the moment, researchers recommend incrementally incorporating additional fish into a diet; consumption even once a week moves a family into the “high” fish-eating group as defined in the study.
“Doing that could be a lot easier than nudging children about going to bed,” Raine says. “If the fish improves sleep, great. If it also improves cognitive performance—like we’ve seen here—even better. It’s a double hit.”