A new Spanish study published in the Journal of Pediatrics finds that a mother’s diet during pregnancy may affect her child’s risk for symptoms of attention-deficit/hyperactivity disorder (ADHD).
Researchers from the Barcelona Institute for Global Health (ISGlobal) analyzed samples of umbilical cord plasma to measure the levels of omega-6 and omega-3 reaching the fetus. They discovered that a higher omega-6:omega-3 ratio was linked to a greater risk for ADHD symptoms at seven years of age.
Omega-6 and omega-3 are long-chain polyunsaturated fatty acids that play a crucial role in the function and structure of the central nervous system, particularly during the later stages of pregnancy. These two fatty acids compete for entrance into cell membranes and are primarily obtained through diet.
Since omega-6 and omega-3 have opposing functions — omega-6 promotes systemic pro-inflammatory states, while omega-3 promotes anti-inflammatory states — a balanced intake of these two fatty acids is important. Previous research had shown that children with ADHD symptoms have a higher omega-6:omega-3 ratio.
“This study adds more evidence to the growing body of research on the importance of maternal diet during pregnancy,” said ISGlobal researcher Jordi Júlvez, Ph.D., a co-author of the study.
“The nutrient supply during the earliest stages of life is essential in that it programs the structure and function of the organs, and this programming, in turn, has an impact on health at every stage of life. As the brain takes a long time to develop, it is particularly vulnerable to misprogramming. Alterations of this sort could therefore lead to neurodevelopmental disorders.”
For the study, the team looked at data from 600 children living in four Spanish regions (Asturias, Basque Country, Catalonia and Valencia) who were enrolled in the INMA Project. They analyzed umbilical cord plasma samples and data from questionnaires completed by the children’s mothers.
ADHD symptoms were assessed using two standard questionnaires: the first completed by the children’s teachers at age four, and the second by their parents at age seven.
The researchers analyzed the number of symptoms in the children who met the diagnostic criteria for ADHD (minimum six symptoms) and also in the children with a smaller number of ADHD symptoms.
The findings reveal that, at age seven years, the number of ADHD symptoms increased by 13 percent per each unit increase in the omega-6:omega-3 ratio in umbilical cord plasma.
The ratio of the two fatty acids was tied to the number of ADHD symptoms present but not with diagnosis of the disorder, and only in the assessment carried out at seven years of age. The authors suggest that the evaluation conducted at four years of age may have been affected by a measurement error because ADHD symptoms reported at early ages may be caused by a neurodevelopmental delay falling within the normal range.
“Our findings are in line with previous studies that established a relationship between the omega-6:omega-3 ratio in mothers and various early neurodevelopmental outcomes,” said Mónica López-Vicente, Ph.D., ISGlobal researcher and lead author of the study.
“Although the association was not clinically significant, our findings are important at the level of the population as a whole,” she said.
“If a large proportion of the population is exposed to a high omega-6:omega-3 ratio, the distribution for ADHD symptom scores would likely move to the right and the prevalence of extreme values would increase, leading to a negative impact on the community’s health costs and productivity.”