Attention deficit hyperactivity disorder or ADHD has been on the rise since surveys began in 1997.
And, according to the Centers for Disease Control and Prevention (CDC), about 9.4% of children 2-17 years of age (6.1 million) received a diagnosis of ADHD in 2016.
As with autism, the CDC says it’s hard to tell whether this apparent rise reflects a real increase in rates of ADHD, or a rise in the number of children being diagnosed.
Regardless, ADHD is a serious problem for children and their parents, and due to impairment of a child’s ability to read and learn, its negative effects can persist throughout life.
We’ve long had substantial evidence that diet plays a role in triggering or promoting ADHD — and that includes the diets of pregnant and nursing mothers, which impact child development.
To learn more about the role of diet in promotion of ADHD, see Attention Deficit Risks Raised by American Diet.
One of the key deficiencies of the standard American diet is its extreme excess of omega-6 fatty acids, and a striking lack of omega-3 fatty acids — whose most nutritionally valuable forms (DHA and EPA) come from seafood.
Studies published over the past decade suggest that seafood-source omega-3s may reduce the risk for and severity of ADHD. For more on that, see Omega-3s' ADHD Benefits Clarified.
And, as we reported in see Moms' Fish Intake Affects Kids' ADHD Risk, there’s evidence that the diets of pregnant mothers can affect a child’s risk for the disorder.
Now, the results of an unusually credible study from Spain support the idea that a mother’s intake of seafood-source omega-3s — relative to their intake of omega-6 fatty acids — can affect their child’s risk for ADHD.
Spanish cord-blood study links maternal “omega imbalance” to ADHD
The new findings come from Spain’s Barcelona Institute for Global Health (ISGlobal).
The study’s findings are unusually credible because the Spanish team analyzed samples of umbilical cord blood to measure the levels of omega-6 and omega-3 fats that reach the fetus.
In short, the analysis linked a higher omega-6/omega-3 ratio to a higher risk of ADHD symptoms at seven years of age.
The study encompassed 600 children living in four Spanish regions. The Spanish team analyzed umbilical cord-blood samples and data from questionnaires completed by the children’s mothers (López-Vicente M et al. 2019).
ADHD symptoms in the children were assessed using two standard questionnaires, with the first survey being completed by the children’s teachers at age four years, and the second survey completed by their parents at age seven years.
The results showed that, at age seven years, the number of ADHD symptoms in a child increased by 13% per each unit increase in the omega-6/omega-3 ratio in umbilical cord blood.
The researchers analyzed the number of symptoms in the children who met the diagnostic criteria for ADHD (minimum six symptoms) and in the children with a smaller number of ADHD symptoms.
However, the study authors suggest that the lack of a link in children at four years of age may have been less reliable, because ADHD symptoms reported at early ages can be caused by a developmental delay that falls within the normal range of variation.
According to lead researcher Mónica López-Vicente, “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.”
It’s important to note that the link between a high omega 6/omega-6 ratio and risk for ADHD at age 7 was not “clinically significant”.
However, as Dr. López-Vicente said, “Although the association was not clinically significant, our findings are important at the level of the population as a whole.”
In other words, as she explained, “If a large proportion of the population is exposed to a high omega-6/omega-3 ratio [this would lead] to a negative impact on the community’s health costs and productivity.”
“This study adds more evidence to the growing body of research on the importance of maternal diet during pregnancy,” commented study co-author Jordi Júlvez. “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 mis-programming. Alterations of this sort could therefore lead to neurodevelopmental disorders.”
Study strengths and limitations
We should note, as the authors did, that the study has some limitations and strengths.
Why would the “omega ratio” of a pregnant woman’s diet matter?
Omega-6 and omega-3 fatty acids play crucial roles in development of an unborn child’s central nervous system, particularly during the later stages of pregnancy.
These two families of fatty acids compete for incorporation into cell membranes and are primarily derived from a mother’s diet.
Omega-6 fats tend to promote inflammation — especially when it’s present in excess, as in the standard American diet — while omega-3s almost invariably dampen inflammation.
This explains why a balanced intake of these two fatty acids — no more than about four parts omega-6 fats to one part omega-6 fats, versus the 10 or 20 to one ratio in the standard American diet — is so important.
For more on the critical nature of this ratio in people’s diets — and its profound impacts on physical and mental health — see our Omega-3/6 Balance page and the Omega-3/Omega-6 Balance section of our news archive.