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Breastfeeding – why

2025/10/19

Table of contents

What says the research

“Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary.”

The importance of breastfeeding in low-income and middle-income countries is well recognised, but less consensus exists about its importance in high-income countries. In low-income and middle-income countries, only 37% of children younger than 6 months of age are exclusively breastfed. With few exceptions, breastfeeding duration is shorter in high-income countries than in those that are resource-poor. Our meta-analyses indicate protection against child infections and malocclusion, increases in intelligence, and probable reductions in overweight and diabetes. We did not find associations with allergic disorders such as asthma or with blood pressure or cholesterol, and we noted an increase in tooth decay with longer periods of breastfeeding. For nursing women, breastfeeding gave protection against breast cancer and it improved birth spacing, and it might also protect against ovarian cancer and type 2 diabetes. The scaling up of breastfeeding to a near universal level could prevent 823 000 annual deaths in children younger than 5 years and 20 000 annual deaths from breast cancer. Recent epidemiological and biological findings from during the past decade expand on the known benefits of breastfeeding for women and children, whether they are rich or poor.

What do parents know?

Most parents are aware of the overall beneficial impact of breastfeeding on their baby’s health. But few parents are aware that breastfeeding not only protects the child through the transfer of immunoglobulins and other immuno-competent factors, but that breast milk also helps their baby to strengthen and mature its immune system.

Breastfeeding not only strengthens the child’s immune system, but breast milk also contributes to the child’s development. Breastfeeding provides the child with many immuno-protective factors: specific (adapted to the mother’s and child’s environment) and non-specific (those present in the basic composition of breast milk from the beginning, such as IgA, cytokines, human oligosaccharides (about 200), tumour-killing proteins, and many others – the list is long (see below).

Moreover, breastfeeding builds and nourishes the child’s microbiota. Breast milk acts on the intestinal flora and mucous membranes, two important protective filters against pathogens and viruses. As researcher Lars A. Hanson wrote as early as 2004: Breastfeeding protects the baby, and in addition, it nourishes him. Major components of human milk are not primarily for nutrition, but for host defense (see Immunobiology of Human Milk – How Breastfeeding protects babies, 2004) .

Knowledge and research into the dynamic, protective and physiological-immune role of breast milk reveal its important role and lasting impact on the health of the breastfed child – the health of the future adult.

Swiss Paediatric Society: Breastfeeding protects

The Swiss Paediatric Society writes in 2017: “Health benefits: Human milk not only has immediate protective effects in the first few months of life (prevention of infections, particularly gastrointestinal and respiratory tract infections, as well as ear infections), but also long-term health benefits that are still observed after several years. Breastfeeding is said to protect against autoimmune diseases such as type 1 diabetes, chronic inflammatory bowel disease, allergies and coeliac disease; it reduces the risk of being overweight and obese, the risk of developing type 2 diabetes, the risk of hypertension, the risk of hypercholesterolaemia, the risk of developing acute lymphoblastic leukaemia, and it also improves the child’s cognitive development, resulting in a higher intelligence quotient. In fact, human milk is a determining factor in an individual’s health, and its effects continue to be felt years and even decades after the breastfeeding period.” Source: https://www.paediatrieschweiz.ch/fr/recommandations-pour-lalimentation-des-nourrissons-2017/

Breastfeeding and general health

2023 Wang X et al. Breastfeeding in infancy and mortality in middle and late adulthood: A prospective cohort study and meta-analysis. « During a total of 4732,751 person-years of follow-up, 25,581 deaths were identified. Breastfeeding in infancy was associated with lower risks of mortality in middle and late adulthood, with adjusted HRs (95% CIs) of 0.95 (0.93–0.98) for all-cause mortality; 0.91 (0.87–0.96) for cardiovascular mortality and 0.94 (0.874–0.999) for respiratory mortality. » Breastfeeding in infancy is associated with a lower risk of mortality – even decades later – in middle and late adulthood.

Breastfeeding protects against childhood cancer

2024 Protection against childhood leukemia https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2816747 Exclusive Breastfeeding Duration and Risk of Childhood Cancers. Signe Holst Søegaard, P et al. A total of 309 473 children were included (51.3% boys), during 1 679 635 person-years of follow-up. Result : Longer breastfeeding duration may be a potential factor in prevention of childhood B-cell precursor acute lymphoblastic leukemia ALL.t

2024 Signe Holst Søegaard P et al. Exclusive Breastfeeding Duration and Risk of Childhood Cancers. A total of 309 473 children were included (51.3% boys), during 1 679 635 person-years of follow-up. Result : Longer breastfeeding duration may be a potential factor in prevention of childhood B-cell precursor acute lymphoblastic leukemia ALL. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2816747

2021 Su Q et al. Breastfeeding and the risk of childhood cancer: a systematic review and dose-response meta-analysis. Forty-five articles involving 475,579 individuals were included in the meta-analysis. Our study supports a protective role of breastfeeding on the risk of childhood leukemia, also suggesting a non-linear dose-response relationship. Further studies are warranted to confirm the association between breastfeeding and risk of childhood neuroblastoma.

2018 Greaves M. A causal mechanism for childhood acute lymphoblastic leukaemia ALL. “Most cases of childhood ALL are potentially preventable. But how? Lifestyle changes including day care attendance or protracted breastfeeding in the first year of life can be advocated but would be difficult to achieve.” – Despite the author’s sceptical conclusion, GIFA believes that this approach of restoring breastfeeding’s place and support as a preventive factor for acute lymphoblastic leukaemia is a realistic measure.

2015 Efrat L et al. Breastfeeding and Childhood Leukemia Incidence Childhood cancer is a leading cause of mortality among children and adolescents in the developed world and the incidence increases by 0.9% each year. Leukemia accounts for about 30% of all childhood cancer but its etiology is still mostly unknown. The meta-analysis of all 17 studies indicated that compared with no or shorter breastfeeding, any breastfeeding for 6 months or longer was associated with a 20% lower risk for childhood leukemia (odds ratio, 0.80; 95% CI, 0.72-0.90). Conclusions and Relevance  Breastfeeding is a highly accessible, low-cost public health measure. This meta-analysis indicates that promoting breastfeeding for 6 months or more may help lower childhood leukemia incidence, in addition to its other health benefits for children and mothers.

Impact on intellectual performance

2023 Chalifour B et al. The potential role of early life feeding patterns in shaping the infant fecal metabolome: implications for neurodevelopmental outcomes. “Most breastmilk-associated metabolites, which are involved in lipid metabolism and cellular processes like cell signaling, were associated with higher neurodevelopmental scores, while formula-associated metabolites were associated with lower neurodevelopmental scores. These findings offer preliminary evidence that feeding patterns are associated with altered infant fecal metabolomes, which may be associated with cognitive development later in life.” https://www.nature.com/articles/s44324-023-00001-2

2023 Paquette AF et al. The human milk component myo-inositol promotes neuronal connectivity. PNAS 2023 ; 120(30) : e2221413120. Mots-clés : lait humain, myo-inositol, développement cérébral, formation des synapses. The formation and maintenance of brain connectivity are guided by an interplay of genetics, experience, and environment. The impact of these factors can be considered particularly important at two stages of life, when synaptic connections rapidly form in the developing brain and when synapses are gradually lost in aging (1, 2). Diet is one environmental factor, yet the effects of bioactive dietary compounds on the formation and maintenance of neuronal connectivity remain to be defined. In early postnatal development, breast milk is rich in micronutrients and bioactive compounds that could support brain development. Indeed, this complex and dynamic fluid offers short- and long-term health benefits to infants, including increased performance in cognitive tasks (3–5). Further, observational studies on the other side of the lifespan support that dietary factors can be associated with healthy brain aging (6, 7). https://www.pnas.org/doi/10.1073/pnas.2221413120

2023 Adams LJ et al. Infant feeding method and special educational need in 191,745 Scottish schoolchildren: A national, population cohort study. Infant breastfeeding has been associated with reduced physical and mental health problems in childhood which contribute toward special educational need (SEN). Findings:

  • Our findings augment the existing evidence base concerning the advantages of breastfeeding and reinforce the importance of breastfeeding education and support.

2022 Pereyra-Elias R et al. To what extent does confounding explain the association between breastfeeding duration and cognitive development up to age 14? Data from 7,855 singletons born in 2000–2002 and followed up to age 14 years within the UK Millennium Cohort Study were analysed. Findings show that breastfeeding duration is associated with improved cognitive development in children, but it is unclear whether this is a causal relationship or due to confounding. Conclusion: The associations between breastfeeding duration and cognitive scores persist after adjusting for socioeconomic position SEP and maternal cognitive ability, however the effect was modest.

2022 AlThuneyyan DA et al. The Effect of Breastfeeding on Intelligence Quotient and Social Intelligence Among Seven- to Nine-Year-Old Girls: A Pilot Study (2022) “Exclusively breastfed girls had higher IQ and SI (social intelligence) results compared with bottle-fed girls. However, unlike the BMI differences, these results were not statistically significant. This study provides fundamental observational data and can be further modified for use on a larger national-scale level.” This study involved 111 healthy girls, aged 7 to 9 years.

2022 de Weerth C et al, Human milk: From complex tailored nutrition to bioactive impact on child cognition and behavior Several conclusions can be drawn. First, human milk is a tailored nutrition that varies over time, between persons, and with maternal and child factors. Second, there is highly compelling emerging evidence that breast milk is central in nourishing, protecting, and guiding neurological development in human infants. Third, potential effects and mechanisms of lactocrine programming on child cognition and behavior are starting to be uncovered.-

2020 Kim KM et al. Associations between breastfeeding and cognitive function in children from early childhood to school age: a prospective birth cohort study “We found that cognitive development was improved in children that were breastfed for > 3 months. Although these results are supported by previous studies, it is important to note that other factors were reported as larger determinants of cognitive development than breastfeeding. Future studies that examine the underlying mechanism for the association between breastfeeding and cognitive development are warranted.”

2016 Boucher O et al. Association between breastfeeding duration and cognitive development Data come from Spanish multicenter birth-cohort study including 1,346 children mean age = 4.9 years. “After adjustment for several confounders, longer duration of breastfeeding was independently associated with better cognitive development and with fewer autistic traits. -This study provides further evidence of a positive association of breastfeeding with cognitive function apart from socio-environmental factors, and also suggests a protective role against autistic traits. Results are in agreement with recommendations for prolonged breastfeeding duration to promote child development.”

2016 Lee H et al. Effect of Breastfeeding Duration on Cognitive Development in Infants: 3-Year Follow-up Study A total of 697 infants were tested at age 12, 24, and 36 months using the Korean version of the Bayley Scales of Infant Development II (K-BSID-II). After adjusting for covariates, infants who were breastfed for ≥ 9 months had significantly better cognitive development than those who had not been breastfed.

2015 Victora et al. Impact of breastfeeding on intelligence, educational attainment and income at 30 years of age in Brazil Breastfeeding is associated with improved performance in intelligence tests 30 years later, and might have an important effect in real life, by increasing educational attainment and income in adulthood.

2015 Horta BL et al. Breastfeeding and intelligence: a systematic review and meta-analysis. “Breastfeeding is related to improved performance in intelligence tests. A positive effect of breastfeeding on cognition was also observed in a randomised trial. This suggests that the association is causal.” This review is cited in Victora et al. 2016, in Lancet Breastfeeding Series

2010 Isaacs EB et al. Impact of breast milk on IQ, brain size and white matter development. Although observational findings linking breast milk to higher scores on cognitive tests may be confounded by factors associated with mothers’ choice to breastfeed, it has been suggested that one or more constituents of breast milk facilitate cognitive development, particularly in preterms. Because cognitive scores are related to head size, we hypothesised that breast milk mediates cognitive effects by affecting brain growth. We used detailed data from a randomized feeding trial to calculate percentage of breast milk (%EBM) in the infant diet of 50 adolescents.

1999 Anderson JW, Johnstone BM, Remley DT. Breast-feeding and cognitive development: a meta-analysis. Am J Clin Nutr. 1999 Oct;70(4):525-35. Meta-analysis of 11 studies. After adjusting for confounding factors such as maternal cognitive performance and paternal education, the authors conclude that breastfed children are three times more likely to have high cognitive function than non-breastfed children.

Read also the blog article by WBTi France https://wbtifrance.jimdofree.com/2018/04/03/intelligence-artificielle-et-allaitement/


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