According to a new report from the University of Pennsylvania, children who eat fish at least once a week sleep better and have IQ scores that are four points higher on average than those who consume fish less frequently or not at all. These findings were recently published in the journal Scientific Reports.
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 those relationships have never before been connected. This study, conducted by Jianghong Liu, Jennifer Pinto-Martin and Alexandra Hanlon of the School of Nursing and Penn Professor Adrian Raine, reveals 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,” said Liu, the lead author and an associate professor of nursing and public health. “Here we look at omega-3s coming from our food instead of from supplements.” For the work, a cohort of 541 9-year-olds to 11-year-olds in China, 54 percent boys and 46 percent girls, completed a questionnaire about how often they consumed fish in the past month, with options ranging from never to at least once a week. They 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 includes 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, and the number of children in the home.
Analyzing these data points, the Penn team found that children who reported eating fish weekly scored 4.8 points higher on IQ exams than those who said they seldom or never consumed fish. Those whose meals sometimes included fish scored 3.3 points higher. Increased fish consumption was also associated with 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,” Raine said. “We have found that omega-3 supplements reduce antisocial behavior, so it’s not too surprising that fish is behind this.”
The researchers see strong potential for the implications of this study. “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. 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. 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, the team 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. The researchers 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, the 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 said. “If the fish improves sleep, great. If it also improves cognitive performance—like we’ve seen here—even better. It’s a double hit.”
Families that are vegetarian may consider making an exception and giving their children chewable fish oil capsules.
Sadja Greenwood, a Bolinas resident, is a retired physician formerly active at the University of California, San Francisco. Read more of her work at sadjascolumns.blogspot.com.