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Why are breastfed babies smarter?

Breastfeeding has many benefits for both mother and baby. One of the most researched benefits is its positive effect on a baby’s cognitive development and intelligence. Studies have consistently shown that breastfed babies tend to be smarter and have higher IQs than formula-fed babies.

How does breastfeeding affect brain development?

There are several ways breastfeeding supports brain development in babies:

  • Breast milk contains nutrients critical for brain growth like docosahexaenoic acid (DHA) and arachidonic acid. These long-chain fatty acids are absorbed better from breast milk than formula.
  • The physical act of breastfeeding supports development. Sucking promotes nerve maturation in the part of the brain involved in language.
  • Skin-to-skin contact and visual stimulation during nursing activate areas in the brain promoting cognitive and emotional growth.
  • The hormones and growth factors like epidermal growth factor, nerve growth factor, and insulin in breast milk also aid in brain cell maturation.
  • Breastfeeding may also benefit brain development by providing protection against infections and inflammation which can negatively impact neurodevelopment.

What does research say about breastfeeding and IQ?

Many studies have analyzed the association between breastfeeding and intelligence:

  • A 2015 study published in The Lancet followed up children 30 years after infancy. Those breastfed for longer had higher IQs, more years of education, and higher monthly incomes.
  • In a 2013 study, adolescents who were breastfed had IQs that were 3.76 points higher compared to those who were formula-fed.
  • 2008 research found a dose-response relationship between breastfeeding duration and IQ. Each additional month of breastfeeding was associated with a 0.35 point increase in IQ.
  • A 2002 meta-analysis concluded that breastfed babies had an IQ advantage of 2.66 points over formula-fed infants in later childhood and adolescence.

The IQ differences associated with breastfeeding often persist into adulthood. This indicates breastfeeding has long-lasting effects on cognitive abilities.

Duration of breastfeeding and IQ

Many studies have found a correlation between longer duration of breastfeeding and higher IQ. For example:

  • Babies breastfed for over 12 months had IQs that were 4 points higher compared to those breastfed for less than 3 months, according to a 2015 analysis.
  • In a 2005 study, babies breastfed for more than 8 months had IQs around 7 points higher at age 6-7 years versus those breastfed for 4 months or less.
  • 2014 research in Brazil demonstrated that predominant breastfeeding for 6-12 months led to an IQ advantage of 3.1 points at age 30 years.

This indicates longer duration of exclusive and total breastfeeding is associated with greater cognitive benefits for the infant.

Does mother’s IQ matter?

Some argue the correlation between breastfeeding and IQ is related to the mother’s intelligence rather than breast milk itself. However, research shows breastfeeding boosts IQ regardless of the mother’s IQ:

  • A 2009 study controlled for maternal IQ and education and still found breastfed infants had higher IQs at age 8 years.
  • 2014 research in Brazil found that breastfeeding predicted IQ even after adjusting for family sociodemographic variables like maternal education and income.
  • A 2007 analysis concluded that only 25% of the beneficial effect of breastfeeding on cognition could be explained by maternal IQ.

While intelligent mothers may be more likely to breastfeed, studies indicate breastfeeding itself plays an independent role in raising IQ.

Criticism of breastfeeding research

Some experts have questioned the methodology of breastfeeding studies and whether they adequately control for confounding factors like maternal socioeconomic status:

  • A 2005 review argued that flaws in study design and control of confounders weakened claims about breastfeeding’s impact on IQ.
  • Factors like prenatal care, smoking, nutrition, and education also influence IQ but are challenging to adjust for.
  • Randomized controlled trials are difficult to perform on breastfeeding because mothers cannot ethically be assigned to breastfeed.

While breastfeeding research has limitations, the consistently positive effect of breastfeeding on cognitive development across numerous studies is compelling.

Breast milk components linked to higher IQ

Certain components of breast milk may be especially beneficial for cognitive development:

Long-chain polyunsaturated fatty acids

The long-chain fatty acids DHA and arachidonic acid play key roles in brain growth and architecture. Compared to formula, breast milk contains higher concentrations and bioavailability of these fatty acids:

  • Infants fed formula with DHA and arachidonic acid closer to levels in breast milk for 4 months had IQs 2.8 points higher at age 6 years (2017 study).
  • Breastfed babies had greater white matter development at age 1 year linked to higher DHA percentages in breast milk (2018 research).


These complex sugars in breast milk provide nutrition for beneficial gut bacteria. Gut flora impacts brain development and behavior:

  • Breastfed infants had higher levels of beneficial bifidobacteria and lactobacilli bacteria compared to formula-fed infants (2011 study).
  • Breast milk oligosaccharides increased brain-derived neurotrophic factor (BDNF) in animal studies – BDNF supports learning, memory and neuron growth (2015 research).


Choline is needed for the memory-related neurotransmitter acetylcholine. Choline also aids brain cell membrane formation and myelination:

  • Infants fed choline-supplemented formula had better visuospatial memory than infants fed standard formula (2013 study).
  • Breast milk is much higher in choline than formula – mature breast milk contains 1.5 times more compared to infant formula (2018 research).

Hormones and growth factors

Developmental hormones and growth factors in breast milk like erythropoietin, nerve growth factor, insulin, and IGF-1 promote structural and functional brain maturation.

Long-term benefits beyond IQ

The advantages of breastfeeding extend beyond just IQ:

  • Academic achievement – Breastfed children score higher on subject tests and have higher grade point averages (2006 study).
  • Income – Young adults who were breastfed earned around 10% more income each month compared to their formula-fed peers (2015 research).
  • Memory – Infants breastfed at least 2 months had better memory function when tested at 6 months (2017 study).
  • Executive function – Adolescents breastfed as babies had improved planning, self-control and ability to switch between tasks (2016 study).

Thus, breastfeeding during infancy appears to impart life-long benefits on many different aspects of cognition and intellectual performance.


Researchers have proposed several mechanisms for how breastfeeding enhances cognition and IQ:

Nutrients in breast milk

The fatty acids, vitamins, proteins and sugars uniquely found in breast milk nourish growing brain cells and neuronal connectivity.

Bonding and attachment

Skin-to-skin contact during nursing fosters emotional bonding, which provides an optimal environment for infant brain development.

Protection from infections

Breast milk contains immunoglobulins, enzymes, and immune cells that protect against infections and inflammation in the brain.

Gut microbiota

Breast milk oligosaccharides promote growth of healthy gut bacteria which release metabolites that influence brain function.

Gene expression

Breastfeeding alters gene expression in pathways involved in cognitive processing and brain plasticity.


Overall, a large body of research indicates breastfed babies tend to have higher IQs, better memory, increased academic success, higher incomes, and superior performance on intelligence tests. While confounding factors can influence studies, the consistent IQ advantage among breastfed infants is compelling given the number and quality of supporting studies.

The cognitive benefits of breastfeeding stem from many components of breast milk that nourish brain cell growth and development. Breastfeeding also provides protection from inflammation and fosters mother-infant bonding critical for cognitive and emotional development. Given the lifelong intellectual advantages, breastfeeding should be recommended whenever possible to nourish infants both nutritionally and cognitively.