Blood concentrations of omega-3 fatty acids in school-aged children in the United Kingdom (UK) are well below the minimum recommended for good cardiovascular health in adults, according to a new study.
For details of this research study, see
And for information on the subsequent randomised controlled treatment trial of supplementation with omega-3 DHA, carried out in a subset of the children who took part in this initial, cross-sectional study, see also:
The research also found that low levels of omega-3, particularly docosahexaenoic acid (DHA), which is found in fish, seafood, and some algae, are associated with worse performance on reading tests and working memory, and more symptoms of attention-deficit/hyperactivity disorder (ADHD) in the children, even after controlling for sex and socioeconomic status.
"The blood omega status in these kids is worryingly low, given what is known about omega-3 and its benefits for brain development, and cardiovascular and immune system health," said study author Alexandra J. Richardson, DPhil, a senior research fellow at the University of Oxford, UK, and founder-director of the charity Food And Behaviour Research.
The study was published in PLoS ONE. The study was funded by Martek Biosciences Inc.
This study formed the screening stage of a previously published randomized controlled intervention study that included 362 healthy children aged 7 to 9 years from primary schools in Oxfordshire, a large county in the UK, who had low reading scores. The DOLAB study reported that supplementation with 600 mg DHA daily for 16 weeks improved reading and behavior in children with the lowest 20% of reading scores.
The DOLAB study followed a 2005 study — the Oxford Durham Study — that showed "highly meaningful" benefits for reading and spelling from long-chain omega-3 supplementation, said Dr. Richardson.
The current cross-sectional analysis, which included 493 children, aimed to determine the status of long-chain polyunsaturated fatty acids (LC-PUFAs) in these children and its relevance for cognition and behavior.
Researchers analyzed fatty acids through fingertip-prick whole-blood samples. They measured reading proficiency using the well-validated Word Reading Achievement subtest of the British Ability Scales 2nd Edition (BAS II) and working memory using the Recall of Digits Forward and Recall of Digits Backward subtests form the BAS II.
Parents and teachers rated ADHD-type symptoms, such as inattention, hyperactivity, and impulsivity, in the children using the long version of the Connors Rating Scales. These measurement tools are commonly used to assess behavior problems related to ADHD and have been successfully used in previous studies on the relationships between nutrient status and behavioral problems.
Although the children had been underperforming in reading according to national tests carried out at age 7 years, formal testing as part of this study showed that the actual distribution of reading scores in this screening sample was within normal population ranges. Only the children whose scores still placed them in the lowest third of the normal range were entered into the subsequent treatment trial, explained Dr. Richardson.
In this current analysis, the average blood omega-3 LC-PUFA concentration in the children was 2.46% and was slightly lower in girls than boys. In adults, concentrations of 8% to 12% are considered the optimal range for general health, while those below 4% are considered to signify high cardiovascular risk.
The study showed that reading scores were significantly and positively associated with the omega-3 fatty acids DHA (P < .003), docosapentaenoic acid (DPA; P < .04), eicosapentaenoic acid (EPA; P < .005), and the omega-3 index (EPA+DHA; P < .04). Total omega-6 fatty acids also showed a positive correlation with reading.
Results were similar for working memory. Scores for Recall of Digits Forward were significantly and positively associated with DHA (P < .003), DPA (P < .04), EPA (P < .005), the omega-3 index (P < .001), and total omega-3 (P < .004).
In both reading and working memory, there was a slight negative association with the shorter-chain omega- 3 stearidonic acid (P < .04 in both cases).
The associations held up even after adjustment for sex and socioeconomic status (P = .002 for EPA; P = .001 for DHA; P < 0.001 for omega-3 index).
These data "look fairly comparable" with preliminary results from studies of general population groups in other European countries, said Dr. Richardson. "The omega-3 status in children and younger adolescents seems to be lower than in any other age group, which probably reflects their dietary habits," said Dr. Richardson.
Indeed, in this current study, parent reports showed that almost 9 of 10 children (88.2%) failed to meet current UK dietary guidelines of eating 2 portions of fish per week.
According to Dr. Richardson, the dietary habits of school-aged children are heavily influenced by peer pressure.
"More attention needs to be paid to this," she said. "Omega-3s are critical nutrients but are at suboptimal levels in the diet of most people in developed countries. In addition to their key roles in cardiovascular health and immune function, the long-chain omega-3 (EPA and DHA) are needed for normal brain structure and brain function — so I think we should be concerned that they are not in the diet in sufficient quantities for optimal mental performance and well-being."
She added that "there's enough evidence out there to show that people would be well advised to get enough long-chain omega-3 into their diets one way or the other, whether it's through functional foods or supplements or just by eating fish and seafood."
It's always best to get omega-3 and other nutrients from the diet, but information from the study on children's fish-eating habits showed that they "just weren't doing it," said Dr. Richardson.
Because the study was restricted to children whose first language was English, the findings may not apply to ethnic minority groups, particularly given that important genetic influences on omega-3 fatty acid metabolism and status are known to vary with ancestry.
Dr. Richardson and her colleagues have already embarked on a follow-up DOLAB study to try to replicate the results of this previously published intervention study. "We are focusing on the lowest fifth of readers, the bottom 20% of the normal population range. That was where we found a treatment effect of 600 mg of DHA a day vs placebo."
Reached for a comment, Jeannine Baumgartner, PhD, nutrition scientist, Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa, said the study "is a technically sound piece of research."
"This study extends the current knowledge on omega-3 fatty acid nutrition and child developmental outcomes, specifically on reading ability, which is often a predictor of continued academic achievement."
The study results also might help explain the results of the DOLAB trial that reported significant effects of DHA supplementation on reading ability and parent-rated behavior in the children whose initial reading performance was below the 20th percentile, said Dr. Baumgartner.
"The significant association between reading ability and omega-3 fatty acid status reported in this cross-sectional analysis from the DOLAB screening indicates that these children were likely to have the lowest omega-3 fatty acid status and therefore to benefit most from supplementation."
Dr. Baumgartner pointed out that previous studies investigating the effects of omega-3 fatty acids supplementation on cognitive and behavioral outcomes in healthy children have had mixed results; that unlike other nutrients, a cutoff for omega-3 fatty acid deficiency is not yet defined; and that many of the children in the current study did not meet recommendation for fish consumption.
"These findings, together with the finding that lower omega-3 fatty acid status was associated with poorer reading ability and parent-rated behavioral problems, highlight the importance of eating 2 servings of fish, particularly fatty, per week," she said. "However, in cases where increasing the fish consumption is not an option, omega-3 fatty acid supplementation can be a good alternative."
More research is needed to determine what level of supplementation has a beneficial effect on cognition and behavior in healthy schoolchildren, as well as to investigate dietetic influences that may affect omega-3 fatty acid metabolism, added Dr. Baumgartner.