There have been reports in the media of a new study which has suggested that DHA and other Omega 3 fatty acids, that are sometimes added to infant formula and occur naturally in breastmilk, do not make children more intelligent.
It is reported that the study, conducted by the University of Southampton, followed a cohort of 241 children from birth until four years old to investigate the relationship between breastfeeding and the use of docosahexaenoic acid (DHA) fortified formula in infancy, and performance in tests of intelligence. It is reported that the researchers found that after they had taken account of the influence of mothers' intelligence and level of education there was no relationship between the estimated total intake of DHA in infancy and a child's IQ.
According to the Press Association, Dr Catharine Gale, who led the study, said: "This study helps to dispel some of the myths surrounding DHA. We do know that there are clear health benefits to breastfeeding but DHA, which is naturally present in breast milk and added into some formulas, is not the secret ingredient that will turn your child into an Einstein.”
Although the specific focus on the influence of DHA on intelligence is interesting, and backs up previous studies that suggest long chain polyunsaturated fatty acids added to formula do not significantly enhance intelligence (Fewtrell MS et al (2002). Double-blind, randomized trial of long-chain polyunsaturated fatty acid supplementation in formula fed to preterm infants. Pediatrics 110: 73-82), much of the subsequent media coverage has led with the statement that breastfeeding in itself has no effect on intelligence.
The association of breastfeeding with higher IQ has been shown in the following studies:
Quigley MA, Hockley C, Carson C et al (2009) Breastfeeding is associated with improved child cognitive development: evidence from the UK Millennium Cohort Study. J Epidemiol Community Health; 63(Suppl_2):8
A total of 11,801 white singleton children were assessed according to their gestational age at birth; term (37-42 weeks, moderately preterm (33-36 weeks) and very preterm (28-32 weeks) and also according to breastfeeding status (ever vs never; and duration of any and exclusive breastfeeding). At age five the children were tested using a validated tool – the British Ability Scales (BAS) test. The researchers found that the mean BAS naming vocabulary score decreased with prematurity. After adjusting for confounders (including the baby’s sex and birthweight; the mother’s age, education, social class, smoking and alcohol in pregnancy, and whether this was her first child), ever breastfeeding was significantly associated with a higher mean BAS naming vocabulary score in children born at term with a stronger effect in children born moderately preterm or very preterm and this also increased with each additional month of breastfeeding. A similar effect of breastfeeding was observed when using other BAS tests such as pattern construction and picture similarities scales. The authors argue that these results, based on one of the largest observational studies of the effect of breastfeeding and child development, suggest that breastfeeding is associated with improved cognitive development, particularly in those born preterm. Link.
Kramer MS, Aboud F, Mironova E. (2008) Breastfeeding and child cognitive development: New evidence from a large randomized trial. Arch Gen Psychiatry 2008: 65; 578-584
The evidence that breastfeeding improves cognitive development is based generally on observational studies and therefore may be affected by differences in the breastfeeding mother's behavior or her interaction with the infant. The PROBIT study followed up children from the original cohort at 6.5 years of age to assess whether prolonged and exclusive breastfeeding improves children's cognitive ability. A total of 17,046 healthy breastfeeding infants were enrolled, of whom 13,889 (81.5%) were followed up at age 6.5 years. The researchers measured IQ scores on the Wechsler Abbreviated Scales of Intelligence and teacher evaluations of academic performance in reading, writing, mathematics, and other subjects. The experimental intervention led to a large increase in exclusive breastfeeding at age three months and a significantly higher prevalence of any breastfeeding at all ages up to and including 12 months. The experimental group had higher mean scores on all of the Wechsler Abbreviated Scales of Intelligence measures for IQ. Teachers' academic ratings were significantly higher in the experimental group for both reading and writing. The researchers conclude that their results demonstrate that prolonged and exclusive breastfeeding improves children's cognitive development. Link.
Horta B et al (2007) Evidence on the long-term effects of breastfeeding. WHO
Pooled data from eight studies which controlled for intellectual stimulation at home. Mean difference for performance in intelligence tests with 1 month+ breastfeeding was 4.9 points. Link.
Caspi A, Williams B, Kim-Cohen J (2007) Moderation of breastfeeding effects on the IQ by genetic variation in fatty acid metabolism.PNAS; 10 1073: 0704292104
Breastfeeding, on average adds 7 extra points to children’s IQ scores, even after allowing for different social backgrounds, when gene FADS2 is present. The gene is closely involved in the way the body processes fatty acids in the diet and is present in 90% of babies. Data from two previous studies of breast-fed infants in Britain and New Zealand, involving more than 3,000 children was analysed. IQ was measured at various points between the ages of five and 13 years. Link.
The development of intelligence in children is a complex process which takes in many factors, including not just the IQ and background of the parents, but also nurturing and early interaction and nutrition, including breastfeeding. Current evidence suggests there is an association between breastfeeding and increased intelligence in children. However, the mechanisms for this link are not yet fully established. Further studies may clarify this association.
