Does breast-feeding influence intelligence quotients at 9 and 10 years of age?

Dynamic changes at high-protein dietary pattern of major fatty acids in healthy lactating women: A systematic review and meta-analysis

BACKGROUND

Fatty acids (FAs) in human milk are important nutrients for infants. They play important roles in energy supply, nervous system development, and metabolic function maintenance. However, how the composition of major milk FAs change with lactation stages remains controversial.

OBJECTIVES

To systematically review the concentration range of major FAs in human milk at various lactation stages.

METHODS

A total of 12 papers involving 50 sets of data with 3507 participants were reviewed according to the PRISMA checklist and flow diagram. The inclusion criteria was the literatures had the FAs contents in breast milk of healthy lactation mothers at three lactation stages and the dietary patterns could be calculated. The exclusion criteria were: the studies were duplicates, were unrelated to dietary patterns or breast milk composition, and/or the study populations were unhealthy. We searched PubMed, the China National Knowledge Infrastructure, WanFang, and Web of science. Agency for Health Care Research and Quality (AHRQ) was used to assess the bias of studies. The mean values of polyunsaturated fatty acids (PUFAs) including docosahexaenoic acid (DHA), arachidonic acid (AA), eicosapentaenoic acid (EPA), α-linolenic acid (ALA), linoleic acid (LA), monounsaturated fatty acids (MUFAs), and saturated fatty acids (SFAs, including lauric acid and palmitic acid), in human milk at three lactation stages (colostrum 1-7 d, transitional milk 8-14 d, mature milk 15 d-3 mo) of healthy lactating women were investigated in terms of the high protein dietary pattern. Publication biases were evaluated by Egger's test.

RESULTS

According to the percentage in total fat of colostrum, transitional milk, and mature milk (% wt/wt), respectively, the results showed that PUFA (25.72%, 24.92%, and 22.69%), AA (0.85%, 0.76%, and 0.59%), DHA (0.53%, 0.47%, and 0.39%), EPA (0.15%, 0.10%, and 0.10%), and MUFA (37.39%, 37.21%, and 36.14%) contents in breast milk decreased with lactation, while another two PUFA forms, LA (17.47%, 17.82%, and 17.48%), and ALA (1.09%, 1.39%, and 1.24%) arrived at a peak in the transitional milk and then decreased in the mature milk, SFA (37.46%, 38.64%, and 40.52%), and lauric acid contents (2.78%, 4.91%, and 4.97%) increased with the lactation stages.

CONCLUSION

These findings could shed light on the dynamic change progress of major FA metabolism, potentially enhancing the knowledge of lactation biology, and improving infant feeding practices to meet their needs.

Soy-Based Infant Formula: Are Phyto-Oestrogens Still in Doubt?

Although Scientific Societies have stated that there are very few indications for the use of soy-based formula (SF) in infant nutrition, their utilization rates have been repeatedly found to be higher than expected. It is likely that a significant role in this regard is played by the belief that the use of SF during infancy can reduce the risk of the development of several diseases later in life. Although no definitive data that can substantiate these claims have been collected, many people perceive soy consumption to confer significant health benefits and might also use soy for infant nutrition. However, not all the problems regarding safety of SF in infants have been definitively solved. Among risks, the potentially toxic role of the phyto-oestrogens contained in SF is not definitively established. In vitro and animal studies have raised suspicions that SF could have potentially negative effects on sexual development and reproductive function, neurobehavioral development, immune function, and thyroid function. Several studies in humans have aimed to assess whether the results of animal studies can be applied to humans and whether SF can be used in infants following the official recommendations. The results are somewhat conflicting. The aim of this narrative review is to discuss what is presently known regarding the impact of phyto-oestrogens in SF on early and late child development. PubMed was used to search for the studies published from January 1980 to June 2017 using the keywords: “soy,” “soy formula,” “child,” “phytoestrogens.” Analysis of the literature showed that a global evaluation of the impact of modern SFs on human development seems to suggest that their use is not associated with relevant abnormalities. Only children with congenital hypothyroidism need adequate monitoring of thyroid function.

Soy-Based Therapeutic Baby Formulas: Testable Hypotheses Regarding the Pros and Cons

Soy-based infant formulas have been consumed in the United States since 1909, and currently constitute a significant portion of the infant formula market. There are efforts underway to generate genetically modified soybeans that produce therapeutic agents of interest with the intent to deliver those agents in a soy-based infant formula platform. The threefold purpose of this review article is to first discuss the pros and cons of soy-based infant formulas, then present testable hypotheses to discern the suitability of a soy platform for drug delivery in babies, and finally start a discussion to inform public policy on this important area of infant nutrition.

Effects of Health and Nutrition on Cognitive and Behavioural Development in Children in the First Three Years of Life: Part 1: Low Birthweight, Breastfeeding, and Protein-Energy Malnutrition

The following paper and its accompanying paper (Grantham-McGregor SM, et al. Effects of health and nutrition on cognitive and behavioural development in children in the first three years of life. Part 2: Infections and micronutrient deficiencies: iodine, iron, and zinc. Food Nutr Bull 1999;20:76–99) review the literature on the conditions that are prevalent and considered to be likely to affect child development and are therefore of public health importance. the reviews are selective, and we have generally focused on recent work, particularly in areas that remain controversial. the reviews are restricted to nutritional and health insults that are important in the first three years of life. Where possible, we have discussed the better studies. This paper considers the effects of low birthweight (focusing on small-for-gestational-age babies) and early childhood protein-energy malnutrition on mental, motor, and behavioural development. We have also included a section on breastfeeding because of its importance to child health and nutrition programmes.

Effects of cow milk versus extensive protein hydrolysate formulas on infant cognitive development

Little research has focused on infant developmental effects, other than growth, of formulas that differ substantially in the form of protein. To examine development of infants fed formulas differing in free amino acid content, we randomized 0.5-month-old infants (n = 79) to either a control group who fed only cow milk formula (CMF) during the first 8 months (CMF8), or to one of two experimental groups: one experimental group fed extensively protein hydrolyzed formula (EHF) for 1-3 months during first 4.5 months (EHF1-3) of life, and the other fed EHF for 8 months (EHF8). The Mullen Scales of Early Learning were administered monthly from 1.5 to 8.5 months to assess fine (FM) and gross (GM) motor control, receptive (RL) and expressive (EL) language, visual reception (VR), and an early learning composite (ELC). Across the 5.5-8.5-month time period, when compared to CMF8 infants, GM scores in EHF1-3 infants averaged 1.5 points higher (95 % CI 0.1, 3.0) and in EHF8 infants 2.2 points higher (95 % CI 0.3, 4.0). Similarly, VR scores averaged 1.9 points higher (95 % CI 0.1, 3.8) in EHF1-3 infants and 2.2 points higher (95 % CI -0.2, 4.5) in EHF8 infants. EHF8 infants' RL scores averaged 1.8 points lower (95 % CI 0.1, 3.6) than CMF8 infants. These data suggest that the form of protein in infant formula may impact cognitive development and that the higher free amino acid content in breast milk may be a contributing factor to the differential cognitive development between breastfed and CMF-fed infants.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov NCT00994747.

Association Between Infant Feeding Practices and First Meaningful Words at First Year of Life

Feeding practices show many benefits for child and cognitive development. The objective was to investigate the association between infant feeding practices and the first meaningful words of Thai children. The participants enrolled in this longitudinal study were 4245 children born between July 2000 and June 2002. They resided in 3 rural and 2 urban areas of Thailand and were followed from birth to childhood. The outcome was time from birth to expression of first meaningful words. Outcome and feeding information were gathered using a diary method, with parents and caregivers recording daily development. Nonstatistically significant corresponding reduction in time to expression of first meaningful words was found among children who were breastfed, and this increased with duration of breastfeeding. Breastfeeding may reduce the time taken for expression of first meaningful words by about 2% (hazard ratio = 0.98; 95% confidence interval = 0.94 to 1.01). No association between infant feeding practices and the expression of first meaningful words was found.

Infant feeding effects on early neurocognitive development in Asian children

BACKGROUND

Breastfeeding has been shown to enhance global measures of intelligence in children. However, few studies have examined associations between breastfeeding and specific cognitive task performance in the first 2 y of life, particularly in an Asian population.

OBJECTIVE

We assessed associations between early infant feeding and detailed measures of cognitive development in the first 2 y of life in healthy Asian children born at term.

DESIGN

In a prospective cohort study, neurocognitive testing was performed in 408 healthy children (aged 6, 18, and 24 mo) from uncomplicated pregnancies (i.e., birth weight >2500 and <4000 g, gestational age ≥37 wk, and 5-min Apgar score ≥9). Tests included memory (deferred imitation, relational binding, habituation) and attention tasks (visual expectation, auditory oddball) as well as the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III). Children were stratified into 3 groups (low, intermediate, and high) on the basis of breastfeeding duration and exclusivity.

RESULTS

After potential confounding variables were controlled for, significant associations and dose-response relations were observed for 4 of the 15 tests. Higher breastfeeding exposure was associated with better memory at 6 mo, demonstrated by greater preferential looking toward correctly matched items during early portions of a relational memory task (i.e., relational binding task: P-trend = 0.015 and 0.050 for the first two 1000-ms time bins, respectively). No effects of breastfeeding were observed at 18 mo. At 24 mo, breastfed children were more likely to display sequential memory during a deferred imitation memory task (P-trend = 0.048), and toddlers with more exposure to breastfeeding scored higher in receptive language [+0.93 (0.23, 1.63) and +1.08 (0.10, 2.07) for intermediate- and high-breastfeeding groups, respectively, compared with the low-breastfeeding group], as well as expressive language [+0.58 (-0.06, 1.23) and +1.22 (0.32, 2.12) for intermediate- and high-breastfeeding groups, respectively] assessed via the BSID-III.

CONCLUSIONS

Our findings suggest small but significant benefits of breastfeeding for some aspects of memory and language development in the first 2 y of life, with significant improvements in only 4 of 15 indicators. Whether the implicated processes confer developmental advantages is unknown and represents an important area for future research. This trial was registered at www.clinicaltrials.gov as NCT01174875.

A hypothesis regarding the molecular mechanism underlying dietary soy-induced effects on seizure propensity

Numerous neurological disorders including fragile X syndrome, Down syndrome, autism, and Alzheimer’s disease are co-morbid with epilepsy. We have observed elevated seizure propensity in mouse models of these disorders dependent on diet. Specifically, soy-based diets exacerbate audiogenic-induced seizures in juvenile mice. We have also found potential associations between the consumption of soy-based infant formula and seizure incidence, epilepsy comorbidity, and autism diagnostic scores in autistic children by retrospective analyses of medical record data. In total, these data suggest that consumption of high levels of soy protein during postnatal development may affect neuronal excitability. Herein, we present our theory regarding the molecular mechanism underlying soy-induced effects on seizure propensity. We hypothesize that soy phytoestrogens interfere with metabotropic glutamate receptor signaling through an estrogen receptor-dependent mechanism, which results in elevated production of key synaptic proteins and decreased seizure threshold.

Safety of soya-based infant formulas in children

Soya-based infant formulas (SIF) containing soya flour were introduced almost 100 years ago. Modern soya formulas are used in allergy/intolerance to cows' milk-based formulas (CMF), post-infectious diarrhoea, lactose intolerance and galactosaemia, as a vegan human milk (HM) substitute, etc. The safety of SIF is still debated. In the present study, we reviewed the safety of SIF in relation to anthropometric growth, bone health (bone mineral content), immunity, cognition, and reproductive and endocrine functions. The present review includes cross-sectional, case-control, cohort studies or clinical trials that were carried out in children fed SIF compared with those fed other types of infant formulas and that measured safety. The databases that were searched included PubMed (1909 to July 2013), Embase (1988 to May 2013), LILACS (1990 to May 2011), ARTEMISA (13th edition, December 2012), Cochrane controlled trials register, Bandolier and DARE using the Cochrane methodology. Wherever possible, a meta-analysis was carried out. We found that the anthropometric patterns of children fed SIF were similar to those of children fed CMF or HM. Despite the high levels of phytates and aluminium in SIF, Hb, serum protein, Zn and Ca concentrations and bone mineral content were found to be similar to those of children fed CMF or HM. We also found the levels of genistein and daidzein to be higher in children fed SIF; however, we did not find strong evidence of a negative effect on reproductive and endocrine functions. Immune measurements and neurocognitive parameters were similar in all the feeding groups. In conclusion, modern SIF are evidence-based safety options to feed children requiring them. The patterns of growth, bone health and metabolic, reproductive, endocrine, immune and neurological functions are similar to those observed in children fed CMF or HM.

Breast milk and cognitive development--the role of confounders: a systematic review

OBJECTIVES

The association between breastfeeding and child cognitive development is conflicted by studies reporting positive and null effects. This relationship may be confounded by factors associated with breastfeeding, specifically maternal socioeconomic class and IQ.

DESIGN

Systematic review of the literature.

SETTING AND PARTICIPANTS

Any prospective or retrospective study, in any language, evaluating the association between breastfeeding and cognitive development using a validated method in healthy term infants, children or adults, was included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Extracted data included the study design, target population and sample size, breastfeeding exposure, cognitive development assessment tool used and participants' age, summary of the results prior to, and following, adjustment for confounders, and all confounders adjusted for. Study quality was assessed as well.

RESULTS

84 studies met our inclusion criteria (34 rated as high quality, 26 moderate and 24 low quality). Critical assessment of accepted studies revealed the following associations: 21 null, 28 positive, 18 null after adjusting for confounders and 17 positive-diminished after adjusting for confounders. Directionality of effect did not correlate with study quality; however, studies showing a decreased effect after multivariate analysis were of superior quality compared with other study groupings (14/17 high quality, 82%). Further, studies that showed null or diminished effect after multivariate analysis corrected for significantly more confounders (7.7±3.4) as compared with those that found no change following adjustment (5.6±4.5, p=0.04). The majority of included studies were carried out during childhood (75%) and set in high-income countries (85.5%).

CONCLUSIONS

Much of the reported effect of breastfeeding on child neurodevelopment is due to confounding. It is unlikely that additional work will change the current synthesis. Future studies should attempt to rigorously control for all important confounders. Alternatively, study designs using sibling cohorts discordant for breastfeeding may yield more robust conclusions.

Polyunsaturated fatty acids and their metabolites in the pathobiology of schizophrenia

Schizophrenia can be considered as a low-grade systemic inflammatory disease with its origins in the perinatal period. It is likely that genetic, environmental, and nutritional factors interact to induce excess production of pro-inflammatory cytokines that, in turn, damage fetal neurons leading to the adult onset of schizophrenia. Polyunsaturated fatty acids (PUFAs) and their metabolites such as lipoxins, resolvins, protectins, maresins and nitrolipids not only have potent neuroprotective action but also are capable of inhibiting the production of pro-inflammatory cytokines. Decreased formation of PUFAs as a result of low activity of Δ(6) and Δ(5) desaturases can result in an increase in the production of pro-inflammatory cytokines due to the absence of negative control exerted by PUFAs and their anti-inflammatory metabolites that, in turn, may predispose to neuronal damage and development of schizophrenia in adult life. Furthermore, PUFAs are essential for brain growth and development. If this proposal is correct, this implies that perinatal and adult supplementation of PUFAs not only prevents but also helps in the treatment of schizophrenia. Furthermore, synthetic analogs of lipoxins, resolvins, and protectins may be of significant benefit in schizophrenia.

Evaluation of dietary intake of lactating women in China and its potential impact on the health of mothers and infants

BACKGROUND

Optimal nutrition for lactating mothers is importance for mother and infants' health and well-being. We determined the nutrient intake and dietary changes during the first 3-month of lactation, and its potential effect on health and disease risk.

METHOD

Personal interviews were conducted to collect a 24 h diet recall questionnaire from 199 healthy lactating women in the postpartum days 2, 7, 30, 90 and healthy 58 non-pregnant women served as the controls.

RESULTS

We found in lactating women (1) the mean daily energy and carbohydrate intake was lower than that of the Chinese Recommended Nutrient Intake (RNI, 2600 Kcal, 357.5 ~ 422.5 g) by 11% ~ 17% and 33% ~ 49%, respectively; (2) the fat intake increased from 3% to 13%, which was 9 ~ 77% higher than the RNI (57 ~ 86.7 g); (3) the protein intake exceeded the RNI of 85 g by 32 ~ 53%; (4) the total calories consumed from carbohydrate (39%-44%), fat (34% ~ 42%) and protein (20%-23%) failed to meet Chinese RNI (5) the intake of vitamin C, B1, folate, zinc, dietary fiber, and calcium was 5% ~ 73% lower than the RNI while vitamin B2, B3, E, iron and selenium intake was 20% to 3 times higher than the RNI. Nutrient intake in the control group was lower for all nutrients than the recommended RNI.

CONCLUSION

Lactating women on a self-selected diet did not meet the Chinese RNI for many important micronutrients, which may influence the nutritional composition of breast milk and thus impact the potential health of mothers and infants. RNI should consider the regional dietary habits and culture. A single national RNI is not applicable for all of China. Nutritional education into the community is needed.

NTP-CERHR expert panel report on the developmental toxicity of soy infant formula

Soy infant formula contains soy protein isolates and is fed to infants as a supplement to or replacement for human milk or cow milk. Soy protein isolates contains estrogenic isoflavones (phytoestrogens) that occur naturally in some legumes, especially soybeans. Phytoestrogens are nonsteroidal, estrogenic compounds. In plants, nearly all phytoestrogens are bound to sugar molecules and these phytoestrogen-sugar complexes are not generally considered hormonally active. Phytoestrogens are found in many food products in addition to soy infant formula, especially soy-based foods such as tofu, soy milk, and in some over-the-counter dietary supplements. Soy infant formula was selected for National Toxicology Program (NTP) evaluation because of (1) the availability of large number of developmental toxicity studies in laboratory animals exposed to the isoflavones found in soy infant formula (namely, genistein) or other soy products, as well as few studies on human infants fed soy infant formula, (2) the availability of information on exposures in infants fed soy infant formula, and (3) public concern for effects on infant or child development. On October 2, 2008 (73 FR 57360), the NTP Center for the Evaluation of Risks to Human Reproduction (CERHR) announced its intention to conduct an updated review of soy infant formula to complete a previous evaluation that was initiated in 2005. Both the current and previous evaluations relied on expert panels to assist the NTP in developing its conclusions on the potential developmental effects associated with the use of soy infant formula, presented in the NTP Brief on Soy Infant Formula. The initial expert panel met on March 15 to 17, 2006, to reach conclusions on the potential developmental and reproductive toxicities of soy infant formula and its predominant isoflavone constituent genistein. The expert panel reports were released for public comment on May 5, 2006 (71 FR 28368). On November 8, 2006 (71 FR 65537), CERHR staff released draft NTP Briefs on Genistein and Soy Formula that provided the NTP's interpretation of the potential for genistein and soy infant formula to cause adverse reproductive and/or developmental effects in exposed humans. However, CERHR did not complete these evaluations, finalize the briefs, or issue NTP Monographs on these substances based on this initial evaluation. Between 2006 and 2009, a substantial number of new publications related to human exposure or reproductive and/or developmental toxicity were published for these substances. Thus, CERHR determined that updated evaluations of genistein and soy infant formula were needed. However, the current evaluation focuses only on soy infant formula and the potential developmental toxicity of its major isoflavone components, e.g. genistein, daidzein (and estrogenic metabolite, equol), and glycitein. This updated evaluation does not include an assessment on the potential reproductive toxicity of genistein following exposures during adulthood as was carried out in the 2006 evaluation. CERHR narrowed the scope of the evaluation because the assessment of reproductive effects of genistein following exposure to adults was not considered relevant to the consideration of soy infant formula use in infants during the 2006 evaluation. To obtain updated information about soy infant formula for the CERHR evaluation, the PubMed (Medline) database was searched from February 2006 to August 2009 with genistein/genistin, daidzein/daidzin, glycitein/glycitin, equol, soy, and other relevant keywords. References were also identified from the bibliographies of published literature. The updated expert panel report represents the efforts of a 14-member panel of government and nongovernment scientists, and was prepared with assistance from NTP staff. The finalized report, released on January 15, 2010 (75 FR 2545), reflects consideration of public comments received on a draft report that was released on October 19, 2009, for public comment and discussions that occurred at a public meeting of the expert panel held December 16 to 18, 2009 (74 FR 53509). The finalized report presents conclusions on (1) the strength of scientific evidence that soy infant formula or its isoflavone constituents are developmental toxicants based on data from in vitro, animal, or human studies; (2) the extent of exposures in infants fed soy infant formula; (3) the assessment of the scientific evidence that adverse developmental health effects may be associated with such exposures; and (4) knowledge gaps that will help establish research and testing priorities to reduce uncertainties and increase confidence in future evaluations. The Expert Panel expressed minimal concern for adverse developmental effects in infants fed soy infant formula. This level of concern represents a "2" on the five-level scale of concern used by the NTP that ranges from negligible concern ("1") to serious concern ("5"). The Expert Panel Report on Soy Infant Formula was considered extensively by NTP staff in preparing the 2010 NTP Brief on Soy Infant Formula, which represents the NTP's opinion on the potential for exposure to soy infant formula to cause adverse developmental effects in humans. The NTP concurred with the expert panel that there is minimal concern for adverse effects on development in infants who consume soy infant formula. This conclusion was based on information about soy infant formula provided in the expert panel report, public comments received during the course of the expert panel evaluation, additional scientific information made available since the expert panel meeting, and peer reviewer critiques of the draft NTP Brief by the NTP Board of Scientific Counselors (BSC) on May 10, 2010 (Meeting materials are available at http://ntp.niehs.nih.gov/go/9741.). The BSC voted in favor of the minimal concern conclusion with 7 yes votes, 3 no votes, and 0 abstentions. One member thought that the conclusion should be negligible concern and two members thought that the level of concern should be higher than minimal concern. The NTP's response to the May 10, 2010 review ("peer-review report") is available on the NTP website at http://ntp.niehs.nih.gov/go/9741. The monograph includes the NTP Brief on Soy Infant Formula as well as the entire final Expert Panel Report on Soy Infant Formula. Public comments received as part of the NTP's evaluation of soy infant formula and other background materials are available at http://cerhr.niehs.nih.gov/evals/index.html.

Breastfeeding, maternal education and cognitive function: a prospective study in twins

The effect of breastfeeding on cognitive abilities is examined in the offspring of highly educated women and compared to the effects in women with low or middle educational attainment. All offspring consisted of 12-year old mono- or dizygotic twins and this made it possible to study the effect of breastfeeding on mean cognition scores as well as the moderating effects of breastfeeding on the heritability of variation in cognition. Information on breastfeeding and cognitive ability was available for 6,569 children. Breastfeeding status was prospectively assessed in the first years after birth of the children. Maternal education is positively associated with performance on a standardized test for cognitive ability in offspring. A significant effect of breastfeeding on cognition was also observed. The effect was similar for offspring with mothers with a high, middle, and low educational level. Breast-fed children of highly educated mothers score on average 7.6 point higher on a standardized test of cognitive abilities (CITO test; range 500–550; effects size = .936) than formula-fed children of mothers with a low education. Individual differences in cognition scores are largely accounted for by additive genetic factors (80%) and breastfeeding does not modify the effect of genetic factors in any of the three strata of maternal education. Heritability was slightly lower in children with a mother with a middle-level education.

Cortical responses to speech sounds in 3- and 6-month-old infants fed breast milk, milk formula, or soy formula

Controversy exists about the safety of soy formula, with the main concern relating to potential estrogenic effects of soy protein. Since estrogens influence early brain development, we compared behavioral development and cortical responses (event-related potentials; ERPs) to speech sounds in infants fed either breast milk or formula (milk- or soy-based). Across-groups ERP measures were generally similar and behavioral measures were within normal ranges, suggesting no important influences of soy formula on behavioral development and brain function during the study period. Analyses relating ERP and behavioral measures revealed diet- and gender-specific emphases that may reflect differences in developmental trajectories of brain-behavior relationships.

Cognitive function in adolescence: testing for interactions between breast-feeding and FADS2 polymorphisms

OBJECTIVES

Breast-fed C-allele carriers of the rs174575 single nucleotide polymorphism in the fatty acyl desaturase 2 (FADS2) gene have been reported to show a 6.4 to 7 IQ point advantage over formula-fed C-allele carriers, with no effect of breast-feeding in GG carriers. An Australian sample was examined to determine if an interaction between breast-feeding and the rs174575 single nucleotide polymorphism had any effect on IQ.

METHOD

This hypothesis was tested in more than 700 families of adolescent twins assessed for IQ and breast-feeding, birth weight, and FADS2 polymorphisms, and parental socioeconomic status and education, and maternal FADS2 status.

RESULTS

No significant evidence for a moderating effect on IQ of rs174575 C-carrier status and breast-feeding was found, and there no effects of maternal FADS2 status on offspring IQ. In addition, no main effects of any FADS2 polymorphisms on IQ were found when the genotype was kept as two-homozygote and one-heterozygote categories and indeed no evidence for effects of breast-feeding on IQ scores after controlling for parental socioeconomic status and education. The investigation was extended to two additional FADS2 polymorphisms (rs1535 and rs174583), but again, although these polymorphisms code alleles affecting fatty acid metabolism, no main or interaction effects were found on IQ.

CONCLUSION

These results support the view that apparent effects of breast-feeding on IQ reflect differential likelihood of breast-feeding as a function of parental education and did not support the predicted interaction effect of FADS2 and breast-feeding on IQ.

Duration of breast feeding and language ability in middle childhood

There is controversy over whether increased breast-feeding duration has long-term benefits for language development. The current study examined whether the positive associations of breast feeding on language ability at age 5 years in the Western Australian Pregnancy (Raine) Cohort, were still present at age 10 years. The Raine Study is a longitudinal study of 2868 liveborn children recruited at approximately 18 weeks gestation. Breast-feeding data were based upon information prospectively collected during infancy, and were summarised according to four categories of breast-feeding duration: (1) never breast-fed, (2) breast-fed predominantly for <4 months, (3) breast-fed predominantly for 4-6 months, and (4) breast-fed predominantly for >6 months. Language ability was assessed in 1195 children at the 10 year follow-up (mean age = 10.58 years; standard deviation = 0.19) using the Peabody Picture Vocabulary Test - Revised (PPVT-R), which is based around a mean of 100 and a standard deviation of 15. Associations between breast-feeding duration and PPVT-R scores were assessed before and after adjustment for a range of sociodemographic, obstetric and psychosocial covariates. Analysis of variance revealed a strong positive association between the duration of predominant breast feeding and PPVT-R at age 10 years. A multivariable linear regression analysis adjusted for covariates and found that children who were predominantly breast-fed for >6 months had a mean PPVT-R score that was 4.04 points higher than children who were never breast-fed. This compared with an increase of 3.56 points at age 5 years. Breast feeding for longer periods in early life has a positive and statistically-independent effect on language development in middle childhood.

Infant feeding practice and childhood cognitive performance in South India

AIM

Several studies have suggested a beneficial effect of infant breastfeeding on childhood cognitive function. The main objective was to examine whether duration of breastfeeding and age at introduction of complementary foods are related to cognitive performance in 9- to 10-year-old school-aged children in South India.

METHODS

The authors examined 514 children from the Mysore Parthenon birth cohort for whom breastfeeding duration (six categories from <3 to > or = 18 months) and age at introduction of complementary foods (four categories from <4 to > or = 6 months) were collected at the first-, second- and third-year annual follow-up visits. Their cognitive function was assessed at a mean age of 9.7 years using three core tests from the Kaufman Assessment Battery for children and additional tests measuring long-term retrieval/storage, attention and concentration, visuo-spatial and verbal abilities.

RESULTS

All the children were initially breastfed. The mode for duration of breastfeeding was 12-17 months (45.7%) and for age at introduction of complementary foods 4 months (37.1%). There were no associations between longer duration of breastfeeding, or age of introduction of complementary foods, and cognitive function at 9-10 years, either unadjusted or after adjustment for age, sex, gestation, birth size, maternal age, parity, socio-economic status, parents' attained schooling and rural/urban residence.

CONCLUSIONS

Within this cohort, in which prolonged breastfeeding was the norm (90% breastfed > or = 6 months and 65% breastfed for > or = 12 months), there was no evidence suggesting a beneficial effect of longer duration of breastfeeding on later cognitive ability.

Home environment, not duration of breast-feeding, predicts intelligence quotient of children at four years

OBJECTIVE

We investigated the relation between duration of breast-feeding in infancy and the intelligence quotient (IQ) of children at 4 y of age in a well-nourished population of an industrialized country.

METHODS

Data on duration of breast-feeding were collected prospectively from a cohort of 302 children born between 1998 and 1999 in Adelaide, Australia. The IQ of the children was assessed at 4 y of age using the Stanford-Binet Intelligence Scale. Information on important predictors of childhood IQ including the quality of the home environment was also collected prospectively. Regression analyses were conducted to examine the effect of duration of breast-feeding on IQ with adjustment for potential confounders.

RESULTS

There was no association between the duration of breast-feeding and IQ of the children. The expected IQ of a child at 4 y of age who was breast-fed for 6 mo was only 0.2 point (95% confidence interval -0.8 to 1.2) higher than that of a child who had never been breast-fed after adjustments for the quality of the home environment and socioeconomic characteristics of families using multivariable regression analysis. The quality of the home environment, as assessed by the Home Screening Questionnaire, was the strongest predictor of IQ at 4 y.

CONCLUSION

There was no association between duration of breast-feeding and childhood IQ in this relatively well-nourished cohort from an industrialized society. In such settings, the apparent benefit of breast-feeding on cognitive function is most likely attributable to sociodemographic factors.

Duration of Breast Feeding and Cognitive Function: Population Based Cohort Study

Some evidence suggests that breast feeding is weakly but positively associated with cognitive function. This association has been robust to adjustment for various confounders. The aim of this paper is to determine if duration of breast feeding is associated with cognitive function in late childhood. Data was abstracted from the 1970 British Cohort Study. 11004 liveborn white singletons born during 5-11 April 1970 in the United Kingdom were followed from birth to 10 years. Cognitive function at 10 years is the dependent variable, a latent construct composed of one ability test and three performance measures. Estimates derived from multiple linear regression and structural equation modeling were compared. Effect sizes were estimated using standardized coefficients (SC). Differences in cognitive function according to breast feeding duration were estimated to be small by multiple linear regression (SC = 0.07) and much smaller and non-significant as estimated by structural equation modeling (SC = 0.02) after adjusting for parental socioeconomic status (SES), birth weight, parity, gestational age, maternal age and maternal smoking. Differences in cognitive function according to duration of breast feeding appear to be small and of little clinical importance as estimated by structural equation modeling.

Breast-feeding and mental and motor development at 51/2 years

OBJECTIVE

Breast-feeding is associated with better child development outcomes, but uncertainty remains primarily due to the close relationship between breast-feeding and socioeconomic status. This study assesses the issue in a low socioeconomic status sample where breast-feeding was close to universal.

METHODS

Seven hundred eighty-four Chilean children were followed longitudinally from infancy. All but four were initially breastfed, 40% nursed beyond 12 months, and infant growth was normal. Child development was assessed at 5(1/2) years by a cognitive, language, and motor test battery. The duration of breast-feeding as the sole milk source was analyzed as a continuous variable, adjusting for a comprehensive set of background factors.

RESULTS

The relationship between breast-feeding and most 5(1/2)-year developmental outcomes was nonlinear, with poorer outcome for periods of breast-feeding as the sole milk source for <2 months or >8 months--statistically significant for language, motor, and one comprehensive cognitive test, with a suggestive trend for IQ.

CONCLUSIONS

The observed nonlinear relationships showed that breast-feeding as the sole milk source for <2 months or >8 months, compared with 2-8 months, was associated with poorer development in this sample. The latter finding requires replication in other samples where long breast-feeding is common and socioeconomic status is relatively homogeneous.

Neurobehavioral evaluation of rhesus monkey infants fed cow's milk formula, soy formula, or soy formula with added manganese

The possible neurobehavioral effects of excess manganese in soy formula were studied. Male rhesus monkeys (n=8/group) were fed a commercial cow's milk based formula (Control), a commercial soy protein based formula (Soy), or the soy formula with added manganese (Soy+Mn) from birth to 4 months of age. Soy formulas naturally have higher manganese (Mn) content than cow's milk formulas. Monkeys received behavioral evaluations, growth measurements, and cerebrospinal fluid (CSF) sampling from birth to 18 months of age. Soy and Soy+Mn groups engaged in less play behavior and more affiliative clinging in social dyadic interactions. These groups also had shorter wake cycles and shorter periods of daytime inactivity than controls. An impulsivity test was sensitive to the Soy group diet. The Soy+Mn group also had a blunted response to the dopamine agonist apomorphine. Groups did not differ significantly in CSF dopamine and serotonin metabolite concentrations, but these concentrations were correlated with several tasks affected by experimental formula. This experiment suggests that components of soy formula, including Mn, may influence brain development as reflected in behavioral measures.

Influence of breast-feeding and parental intelligence on cognitive development in the 24-month-old child

This study was designed to analyze the relationship between breast-feeding and mental development at 24 months of age, independently of the influence of other factors. A total of 238 babies born between October 1995 and February 1998 were enrolled in an observational prospective cohort study. Cognitive development was assessed using the Bayley Infant Development Scale. The results of multiple linear regression analysis showed that infants breast-fed for longer than 4 months scored 4.3 points higher on the mental development scale than those breast-fed for less time. No differences were found in psychomotor development as a function of feeding regimen or duration. The positive linear correlation observed between parental IQ and mental development scores at 24 months was also statistically significant (mother: r = 0.39; p < 0.001; father: r = 0.43; p < 0.001). It may be concluded that breast-feeding for longer than 4 months has a positive effect on the child's mental development at 24 months of age. Parental intelligence also appears to influence cognitive development.

Postpartum maternal moods and infant size predict performance on a national high school entrance examination

BACKGROUND

In an earlier series of studies, we documented the effects of feeding practices and postnatal maternal mood on the growth and development of 226 Barbadian children during the first few months of life. In this report, we extend our earlier studies by examining predictive relationships between infant size, feeding practices and postpartum maternal moods and scores on a national high school examination, the Common Entrance Examination (CEE), at 11 to 12 years of age.

METHODS

Feeding practices, anthropometry, and maternal moods, using Zung depression and anxiety scales and a morale scale, were assessed at 7 weeks (n = 158), 3 months (n = 168), and 6 months (n = 209) postpartum. Background variables including sociodemographic and home environmental factors were also assessed during infancy. CEE scores on 169 of the children in the original study were obtained from the Ministry of Education of Barbados.

RESULTS

In our sample of 86 boys and 83 girls, we found that reduced infant lengths and weights at 3 and 6 months of age were predictive of lower CEE, especially math scores. Children who were smaller at these early ages had significantly lower scores on the examination than did larger children. Postpartum maternal moods, including reports of despair and anxiety, were also found to be significant predictors of lower CEE scores, especially English scores. However, breast-feeding and other feeding practices were not directly associated with the CEE scores. Background variables, which significantly predicted lower CEE scores, included young maternal age at the time of her first pregnancy, more children in the home, less maternal education, and fewer home conveniences. Significant associations between infant anthropometry, maternal moods and CEE scores were all significant even when these background variables were controlled for.

CONCLUSIONS

These findings have important implications for developing interventions early in life to improve academic test scores and future opportunities available to children in this setting.

Safety of soy-based infant formulas containing isoflavones: the clinical evidence

Soy protein has been used in infant feeding in the West for nearly 100 y. Soy protein infant formulas have evolved in this interval to become safe and effective alternatives for infants whose nutritional needs are not met with human milk or formulas based on cow's milk. Modern soy formulas meet all nutritional requirements and safety standards of the Infant Formula Act of 1980. They are commonly used in infants with immunoglobulin E-mediated cow's milk allergy (at least 86% effective), lactose intolerance, galactosemia, and as a vegetarian human milk substitute. Largely as a result of research in animal models, concerns have been voiced regarding isoflavones in soy infant formulas in relation to nutritional adequacy, sexual development, neurobehavioral development, immune function, and thyroid disease. We discuss the available clinical evidence regarding each of these issues. Available evidence from adult human and infant populations indicates that dietary isoflavones in soy infant formulas do not adversely affect human growth, development, or reproduction.

Breast feeding and cognitive development in childhood: a prospective birth cohort study

The aim of this study was to examine prospectively the relation between duration of breast feeding and cognitive outcomes. A cohort study of 2860 children enrolled before birth provided data from 2393 term infants of English-speaking mothers. Of these, complete infant feeding data in the first year of life and verbal cognitive IQ (Peabody Picture Vocabulary Test - PPVT-R) were available for 1450 children at 6 years, and a performance subtest (Perceptual organisation WISC - Block Design) for 1375 children at 8 years. Full breast feeding was categorised as none,> 0 to < 4 months, 4-6 months and> 6 months. Associations between breast-feeding duration and PPVT-R at 6 years and Block Design at 8 years were estimated before and after adjustment for gender, gestational age, maternal age, maternal education, parental smoking and the presence of older siblings. The early cessation of full breast feeding was associated with reduced verbal IQ and the performance subtest. In unadjusted analysis, mean standardised PPVT-R scores were 6.44 points greater (P < 0.0001) in children fully breast fed for> 6 months compared with those never breast fed. After adjustment, mean PPVT-R scores were 3.56 points higher in children fully breast fed for> 6 months compared with those children never breast fed (P = 0.003). Similarly, Block Design scores were higher in those fully breast fed for> 6 months compared with those never breast fed in unadjusted (P = 0.001) but not adjusted analyses (P = 0.223). Interactions between maternal education (four levels) and breast feeding demonstrated a positive association of maternal education on verbal IQ (F = 2.64; P = 0.005) in children breast fed for longer but not on performance (F = 0.74; P = 0.67). The early introduction of milk other than breast milk was associated with reduced verbal IQ after adjustment for social and perinatal confounders. Although these effects were interacting with maternal education, they may act through undefined mechanisms in human milk.

Influence of breast-feeding on mental and psychomotor development

The purpose of this study was to analyze the effects of breast-feeding on cognitive and motor development. A prospective cohort study was carried out enrolling 249 babies from 2 rural and urban areas. Cognitive development was assessed at the age of 18 months. Results show that adjusted scores on the mental development index were 4.6 points higher in babies breast-fed for longer than 4 months than in those breast-fed for less time. No differences in psychomotor development were found as a function of type of feeding. A statistically-significant linear correlation was observed between the duration of breast-feeding and scores for Bayley's mental development index. These data suggest that breast-feeding for longer than 4 months has a positive effect on the baby's mental development measured at 18 months of age. Parental intelligence quotient also seems to have an influence on cognitive development.

How good is the evidence linking breastfeeding and intelligence?

BACKGROUND

We conducted a critical review of the many studies that have tried to determine whether breastfeeding has a beneficial effect on intellect.

DESIGN/METHODS

By searching Medline and the references of selected articles, we identified publications that evaluated the association between breastfeeding and cognitive outcomes. We then appraised and described each study according to 8 principles of clinical epidemiology: 1) study design, 2) target population: whether full-term infants were studied, 3) sample size, 4) collection of feeding data: whether studies met 4 standards of quality- suitable definition and duration of breastfeeding, and appropriate timing and source of feeding data, 5) control of susceptibility bias: whether studies controlled for socioeconomic status and stimulation of the child, 6) blinding: whether observers of the outcome were blind to feeding status, 7) outcome: whether a standardized individual test of general intelligence at an age older than 2 years was used, and 8) format of results: whether studies reported an effect size or some other strategy to interpret the clinical impact of results.

RESULTS

We identified 40 pertinent publications from 1929 to February 2001. Twenty-seven (68%) concluded that breastfeeding promotes intelligence. Many studies, however, had methodological flaws. Only 2 papers studied full-term infants and met all 4 standards of high-quality feeding data, controlled for 2 critical confounders, reported blinding, used an appropriate test, and allowed the reader to interpret the clinical significance of the findings with an effect size. Of these 2, 1 study concluded that the effect of breastfeeding on intellect was significant, and the other did not.

CONCLUSION

Although the majority of studies concluded that breastfeeding promotes intelligence, the evidence from higher quality studies is less persuasive.

Breast feeding and cognitive development at age 1 and 5 years

AIM

To examine whether duration of breast feeding has any effect on a child's cognitive or motor development in a population with favourable environmental conditions and a high prevalence of breast feeding.

METHODS

In 345 Scandinavian children, data on breast feeding were prospectively recorded during the first year of life, and neuromotor development was assessed at 1 and 5 years of age. Main outcome measures were Bayley's Scales of Infant Development at age 13 months (Mental Index, MDI; Psychomotor Index, PDI), Wechsler Preschool and Primary Scales of Intelligence (WPPSI-R), and Peabody Developmental Scales at age 5.

RESULTS

Children breast fed for less than 3 months had an increased risk, compared to children breast fed for at least 6 months, of a test score below the median value of MDI at 13 months and of WPPSI-R at 5 years. Maternal age, maternal intelligence (Raven score), maternal education, and smoking in pregnancy were significant confounders, but the increased risk of lower MDI and total IQ scores persisted after adjustment for each of these factors. We found no clear association between duration of breast feeding and motor development at 13 months or 5 years of age.

CONCLUSION

Our data suggest that a longer duration of breast feeding benefits cognitive development.

Breastfeeding and brain development

Although biochemical evidence seems to support the fact that more DHA is incorporated into the brain of breastfed infants compared with formula-fed infants, whether the levels of DHA in the brain are clinically significant is unclear. Because randomized trials cannot be done, this issue is difficult to study. The effects of breastfeeding on developmental outcome in term infants seems to be small or insignificant. For otherwise healthy children the potential differences are not clinically relevant; however, these small differences distributed over an entire population might have a significant effect on society. Although significant methodologic concerns exist, the effects of breastfeeding on preterm infants may be greater than those for term infants. Extremely low birth weight, premature infants (< 750-1000 g) have been found to have IQs that are 13 points lower than term controls and a 50% to 60% risk for requiring special-education services when they are in school. In these infants, small improvements in IQ and neurologic function could have a much greater effect. Further study of neurodevelopmental outcome in premature infants fed breast milk compared with those fed preterm formula are indicated. This information should not change the practice of encouraging breastfeeding of term and preterm infants because other advantages to breastfeeding exist.

Early cessation of breast milk feeding in very low birthweight infants

This investigation was carried out to comparatively assess the duration of breast milk feeding and to analyze risk factors for early cessation of breast milk feeding in term and very preterm infants. A cohort study was performed in 89 consecutive very low birthweight (VLBW) infants (<1500 g) who survived for at least for one week, and 177 term infants with birthweights >2500 g born in the same hospital matched for gender and multiplicity. Median duration of breast milk feeding, as determined from charts and questionnaires mailed to the mothers at 6 and 12 months corrected age, was 36 days in VLBW infants, compared to 112 days in control infants (P<0.0001). In both VLBW and control infants, smoking during pregnancy, low maternal and low paternal school education were each significantly associated with short duration of breast milk feeding. In VLBW infants, multiple pregnancy and gestational age <29 weeks were each associated with prolonged breast milk feeding, as were maternal age >35 years and spontaneous pregnancy (as opposed to pregnancy following infertility treatment) in term infants. Multivariate analysis revealed that VLBW, smoking and low parental school education were independent negative predictors of breast milk feeding. While these results emphasize the need for special support of VLBW infant mothers promoting lactation, the relationships between smoking, school education and breast milk feeding in both strata show that efforts to increase breast milk feeding require a public health perspective.

A critical evaluation of the evidence on the association between type of infant feeding and cognitive development

This paper presents a critical evaluation of 24 studies on the association between type of infant feeding and cognitive development published over the past 20 years. Validity and generalisability of study findings were assessed according to three methodological standards: clearly defined outcome, specification of partial vs. exclusive breast feeding and control of confounding. Only six of the 24 investigations met all three standards. The most frequent study flaw was failure to distinguish between partial and exclusive breast feeding. Studies which made this distinction found larger IQ advantages to breast-fed infants than studies that did not. Four of the six studies meeting all three standards found an advantage in cognitive development to breast-fed infants of the order of two to five IQ points for term infants and eight points for low birthweight infants. We conclude that the question of whether breast feeding and formula feeding have differential effects on cognitive development has not yet been comprehensively answered. Research to date provides only an indication of the effect of relatively brief durations of partial breast feeding and even briefer durations of exclusive breast feeding. Future studies should measure breast feeding as a continuous dose-type variable, examine longer durations of breast feeding and control for a full range of confounders using techniques that deal appropriately with multicollinearity.

No association between breast-feeding and adult psychosis in two national birth cohorts

BACKGROUND

It has been proposed that breast-feeding might have a protective effect against the development of adult schizophrenia.

AIMS

To test this hypothesis.

METHOD

Using prospective data from two UK national birth cohorts, the feeding histories of those who later developed schizophrenia were compared with the remaining population at risk. Analyses in each cohort were considered to be independent tests of the hypothesis.

RESULTS

There were no differences in feeding histories. In the 1946 birth cohort (n = 4447) 30 cases of DSM-III-R schizophrenia arose by age 43; 24.1% of cases v. 23.6% of controls were entirely bottle-fed; 17.3% v. 12.3% were breast-fed for under 1 month; 58.6% v. 64.1% were breast-fed beyond 1 month. In the 1958 cohort (n = 18,856), 40 cases of CATEGO nuclear schizophrenia arose by age 28; 24.1% of cases v. 31.7% of controls were entirely bottle-fed; 27.6% v. 24.9% were breast-fed for under 1 month; 48.3% v. 43.4% were breast-fed beyond 1 month.

CONCLUSIONS

These findings provide no evidence of any effect of breast-feeding in protecting against the risk of later schizophrenia.

Nutritional deficiencies and later behavioural development

The literature on the long-term effects of nutritional deficiencies in early life is reviewed. The severity and duration of the deficiency, the stage of the children's development, the biological condition of the children and the socio-cultural context may all modify the effect. There is substantial evidence that reduced breast-feeding, small-for-gestational-age birth weight, Fe and I deficiency, and protein-energy malnutrition (PEM) are associated with long-term deficits in cognition and school achievement. However, all these conditions are associated with poverty and poor health, which may account for the association. It is difficult to establish that the long-term relationship is causal, as it requires a randomized treatment trial with long-term follow-up. Such studies are only available for I deficiency in utero and early childhood PEM. Results from these studies indicate that I deficiency has a long-term effect and PEM probably has a long-term effect.