NUTRITIONAL SUPPLEMENTS
FATTY ACID SUPPLEMENTS AND SCHOOL PERFORMANCE Carrie Ruxton PhD, Freelance Dietitian, Cupar, Scotland
Dr Carrie Ruxton is a freelance dietitian who writes regularly for academic and media publications. A contributor to TV and radio, Carrie works on a wide range of projects relating to product development, claims, PR and research. Her specialist areas are child nutrition, obesity and functional foods.
This article was funded by Equazen, manufacturers of evidence-based fatty acid supplements for all ages. The article reflects the opinion of the author.
There is emerging evidence that diet not only affects the structure of the brain, but can influence functional aspects such as memory, learning and behaviour.1 All of these may have a role in school performance. Of all the dietary candidates supporting cognitive function, most interest has been devoted to long chain omega-3 fatty acids (LCn3PUFA), which include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). This makes sense, as the brain has a high lipid and DHA content. Grey matter is 36-40% lipid with around 15-20% of this estimated to be DHA,2 white matter is 49-66% lipid, while myelin has the highest lipid content at 78-81%.3 There is far more DHA than EPA in brain tissues, but while DHA is thought to be vital as a structural fatty acid, EPA’s role is potentially just as important in modulating mood, neural signalling and inflammation.4 A major role of LCn3PUFA in the brain is to increase membrane fluidity which enhances glucose uptake and the transmission of information between neurones.5 In animal models of LCn3PUFA deficiency, detrimental effects on learning, memory and behaviour have been seen, while early work on the fatty acid content of formula milk revealed that inadvertent restriction of DHA and arachidonic acid in infants’ diets produced detrimental effects on IQ and vision.6 Low blood levels of LCn3PUFA have been found in children with attention deficit disorders and, while the association does not confirm cause and effect, fatty acid supplements that include LCn-3PUFA have demonstrated modest positive effects on behaviour and learning in children
with these conditions.7 In addition, in normal healthy children, better LCn3PUFA status has been associated with decreased levels of inattention, hyperactivity, emotional and conduct difficulties and increased levels of prosocial behaviour.8 Given the interest in helping children and young people to achieve their educational potential, this article will look at recent studies which have tested the impact of fatty acid supplementation in healthy children. The results of a consumer survey on the learning environment at home, commissioned by Equazen, will also be discussed. REVIEW OF STUDIES
A literature review was conducted on Medline to locate all randomised controlled trials published in the last 15 years, in which LCn3PUFA supplementation had been offered to healthy children. Various cognitive and learning performance indicators were used as outcomes and are summarised alongside the studies in Table 1. It can be seen that in seven out of nine studies, some, if not all, of the children benefited from increased LCn3PUFA intakes. Interestingly, children tended to benefit more often if they were underperforming, or if their baseline LCn3PUFA status was low. This makes sense, as it suggests that improving fatty acid status helps children to achieve their potential.
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NUTRITIONAL SUPPLEMENTS Table 1: Summary of randomised controlled trials Ref no.
Participants
Intervention details
Statistically significant findings
10
N=616, infants
Tuna oil from around 6 months to 5 years. Academic performance followed up until 14 years.
Nationally standardised academic performance better in children with higher plasma LCn3PUFA, but no other significant differences.
11
N=409, 3-13y indigenous Australians
DHA/EPA (0.75g/d) + GLA for 20 wks Improvement in Draw-A-Person followed by placebo group switching test in intervention group. No treatto active intervention for 20 wks. ment effect for reading or spelling.
12
N=396, 6-10y
Multinutrient capsule (containing 0.09g DHA + 0.02g EPA/d) for 12 months
Improved DHA/EPA status, verbal learning and memory in intervention group.
13
N=362, 7-9y
DHA (0.6g/d) for 16 wks.
Better reading in children with poor reading performance ≤20th centile in intervention group.
N=196, 13-16y
DHA/EPA (0.12/0.16g/d) + multivitamin daily for 12 wks.
Improvement in Conners’ disruptive behaviour scale in intervention group, whereas placebo group worsened.
N=450, 8-10y
DHA/EPA (0.23g/d) for 4 months then all children received active intervention for 8 wks.
Decreased inattention and improved behaviour in intervention group. No differences in IQ or school performance.
14
15
16
N=175, 4y
DHA (0.4g/d) for 16 wks.
Improved performance in listening comprehension and vocabulary acquisition tests in group with better DHA status. No differences in cognitive function overall.
17
N=321, 6-11y with iron deficiency and low LCn3PUFA status
Daily iron (50mg/d) plus DHA/EPA (0.42/0.08g/d) for 4 wks vs iron only or DHA/EPA only.
No differences in cognitive function for DHA/EPA alone but some improvement for iron supplementation.
18
N=90, 10-12y
DHA (0.4g vs 1.0g/d) for 8 wks.
No differences in cognitive function.
Key: DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; GLA, gamma linoleic acid; d, day; wks, weeks; y, years; N, sample size; IQ, intelligence quotient.
Reasons for inconsistency in the overall findings include differences in dosage (0.1 to 1.0g daily), duration of study (four weeks to four years) and a lack of information about baseline fatty acid status in many of the studies. In the two studies where no benefit was seen, the duration was four or eight weeks, which is likely to be too short given that animal studies suggest that two to three months of supplementation are required for LCn3PUFA to be incorporated into brain tissue.9 Another issue affecting most of the studies is the optimal window of opportunity for LCn3PUFA supplementation, which may be prenatally, or in the early months of life according 42
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to animal models and intervention studies in pregnancy.6 Looking at the LCn3PUFA dosage given in successful studies (0.2-0.4g daily) and relating this to the richest natural food source, i.e. oily fish, a considerable intake would be required each week. Figure 1 illustrates this using nutritional data on fish19 and shows that, each week, children would need to eat 150g of salmon, mackerel or sardines, or more than 250g fresh tuna to achieve optimal LCn3PUFA intakes. Other foods do contain LCn3PUFA, e.g. eggs, meat and fortified foods, but the amounts are very low. However, fish oil supplements are an excellent source and typically contain 0.1-0.5g LCn3PUFA per dose.
Achieving 0.2-0.4g/d LCn3PUFA would be difficult for children given that current intakes, estimated from the National Diet and Nutrition Survey, are 0.11 g in 4-10 year olds and 0.12g in 11-18 year olds.20 This is mainly because so few children (6-11%) eat oily fish on a regular basis.18 There is no official advice on fish or LCn3PUFA intakes in children, simply a general population guideline to consume two portions of fish weekly, including one of oily fish. This would be expected to provide the equivalent of 0.45g/day LCn3PUFA (3.0g weekly).21 The recommended portion size of 140g may be too large for younger children, so a practical consideration would be to encourage even a small portion of oily fish weekly then augment this with a daily fish oil supplement. The benefit would be greater in children who do not consume any oily fish as intakes could be increased five-fold with supplementation.5 CONSUMER SURVEY
Parents’ views on learning and the potential effect of LCn3PUFA were investigated in an online survey of 1,000 UK parents of children aged four to 16 years attending mainstream schools. The survey was commissioned by Equazen and conducted by independent pollsters, OnePoll. Just over a third of parents were worried about
their children’s reading ability, yet the average time that children spent reading for pleasure each week was 2.4 hours. In contrast, children spent more than three hours a day on average (21 hours a week) watching TV and playing computer games. There was good knowledge about the best source of LCn3PUFA in the diet, with 74% of parents identifying oily fish, but some confusion about other foods since chicken, wholegrains, fruits, vegetables and dairy products were also mentioned. This probably reflects a lack of understanding about the difference between vegetable sources of omega-3s, i.e. alphalinolenic acid, and fish oil sources, i.e. EPA and DHA, for which there is much better evidence of benefit. Around a quarter of parents gave their children a supplement, typically a multivitamin, but this would not provide EPA, DHA and other fatty acids which support brain health. Indeed, most parents (64%) either felt that their children were not getting enough LCn3PUFA or were unsure about it. This suggests that parents are struggling to determine how much LCn3PUFA their children typically have in their diets and how this relates to recommendations. As more than 40% of parents were getting their health information online, there is an
Figure 1: Amount of oily fish (fresh and frozen) required weekly by children to achieve optimal intakes of LCn3PUFA for school performance
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NUTRITIONAL SUPPLEMENTS
opportunity for healthcare professionals to engage more on this issue using the internet. Another key source of health information cited by parents was GPs, although it is unclear how much knowledge they would have about LCn3PUFA sources and the role of supplements. CONCLUSIONS
The evidence from randomised trials suggests that educational performance in children could benefit from increased LCn3PUFA in the diet, especially if children typically have a low LCn3PUFA status, or are underperforming in reading. Further research needs to be conducted, with consistent durations, dose, baseline levels and participant selection, to ensure better
comparisons across studies. The optimal ratio between DHA and EPA, as well as a role for other fatty acids, such as gamma linolenic acid, should also be considered in future trials. For example, early work on an EPA/DHA/GLA formulation has demonstrated a positive impact on writing and spelling (Equazen, in press). Increasing oily fish consumption is the best food-based method for improving LCn3PUFA status, but current uptake of official advice on fish is very low in children. Until this can be resolved, a daily fish oil supplement is a simple and useful way for parents to help their children meet recommended levels of LCn3PUFA and support their educational performance.
References 1 Fernstrom JD (2000). Can nutrient supplements modify brain function? Am J Clin Nutr 71: 1669S-73S 2 McNamara RK et al (2006). Role of omega-3 fatty acids in brain development and function: potential implications for the pathogenesis and prevention of psychopathology. Prostaglandins Leukot Essent Fatty Acids 75: 329-349 3 O’Brien JS and Sampson EL (1965). Lipid composition of the normal human brain: grey matter, white matter, and myelin. Journal of Lipid Research 6: 537-544 4 Martins JG (2009). EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acids supplementation in depression: Evidence from a meta-analysis of randomised controlled trials. J Am Coll Nutr 28: 525-542 5 Calder PC and Yaqoob P (2010). Understanding omega-3 polyunsaturated fatty acids. Postgraduate Medicine 12: 148-157 6 Kuratko CN et al (2013). The relationship of docosahexaenoic acid (DHA) with learning and behaviour in healthy children: A review. Nutrients 5: 2777-2810 7 Ruxton C and Derbyshire E (2013). Fatty acids in the management of ADHD. Complete Nutrition 13: 85-87 8 Kirby A et al (2010). Children’s learning and behaviour and the association with cheek cell polyunsaturated fatty acid levels. Res Dev Disabil 31: 731-42 9 Frensham LJ et al (2012). Influences of micronutrient and omega-3 fatty acid supplementation on cognition, learning, and behaviour: methodological considerations and implications for children and adolescents in developed societies. Nutr Rev 70: 594-610 10 Brew BK et al (2015). Omega-3 supplementation during the first five years of life and later academic performance: a randomised controlled trial. Eur J Clin Nutr 69: 419-24 11 Parletta N et al (2013). Effects of fish oil supplementation on learning and behaviour of children from Australian Indigenous remote community schools: a randomised controlled trial. Prostaglandins Leukot Essent Fatty Acids 89: 71-9 12 Osendarp S, Baghurst KI, Bryan J et al (2007). Effect of a 12-month micronutrient intervention on learning and memory in well-nourished and marginally nourished school-aged children, two parallel, randomised, placebo-controlled studies in Australia and Indonesia. Am J Clin Nutr 86: 1082-1093 13 Richardson AJ et al (2012). Docosahexaenoic acid for reading, cognition and behaviour in children aged 7-9 years: a randomised, controlled trial (the DOLAB Study). PLoS One 7: e43909 14 Tammam JD et al (2016). A randomised double-blind placebo-controlled trial investigating the behavioural effects of vitamin, mineral and n-3 fatty acid supplementation in typically developing adolescent schoolchildren. Br J Nutr 115: 361-73 15 Kirby A et al (2010). A double-blind, placebo-controlled study investigating the effects of omega-3 supplementation in children aged 8-10 years from a mainstream school population. Res Dev Disabil 31: 718-30 16 Ryan AS and Nelson EB (2008). Assessing the effect of docosahexaenoic acid on cognitive functions in healthy, preschool children: a randomised, placebo controlled, double-blind study. Clin Pediatr 47: 355-362 17 Baumgartner J et al (2012). Effects of iron and n-3 fatty acid supplementation, alone and in combination, on cognition in school children: a randomised, doubleblind, placebo-controlled intervention in South Africa. Am J Clin Nutr 96: 1327-38 18 Kennedy DO et al (2009). Cognitive and mood effects of eight weeks’ supplementation with 400mg or 1000mg of the omega-3 essential fatty acid docosahexaenoic acid (DHA) in healthy children aged 10-12 years. Nutr Neurosci 12: 48-56 19 Ruxton CHS (2011). The benefits of fish consumption. Nutr Bull 36: 6-19 20 Gibbs R (2012). Personal communication. Figures calculated from the National Diet and Nutrition Survey rolling programme 2008-11 21 Scientific Advisory Committee on Nutrition/Committee on Toxicology (2004). Advice on fish consumption: benefits and risks. TSO: London
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