Breast is Best – The Critical Role of Breastfeeding in Infant Brain Development

Reviewed by Tamzyn Murphy RD, MSc

Introduction: Breastfeeding Is More Than Nourishment

As we celebrate World Breastfeeding Week 2025, it’s time to re-examine one of nature’s most profound nutritional blueprints: breast milk. At Nutrition Network, we stand firm in our support for evolutionarily consistent infant nutrition — and that means promoting breastfeeding as not only the biological norm, but as a fundamental tool for safeguarding neurodevelopmental health.

As Dr. Robert Cywes powerfully argues in our Ketogenic: The Science and Practice of Therapeutic Carbohydrate Restriction training, “no mammal exists without breast milk.” It is the starting point of life, a uniquely adapted nutrient delivery system designed over millennia to fuel and shape the developing human brain.

And when it comes to preventing neurodevelopmental disorders like autism, ADHD, and cognitive dysfunction, breast milk is not just beneficial — it is protective.

👉 Learn more in our Ketogenic Training

Breast Milk: Nature’s Ketogenic Superfood

Dr. Cywes describes breast milk as “essentially a lipid delivery system,” composed of approximately 50% fat, of which a substantial portion is saturated fat and cholesterol. These fats are not incidental — they are central to brain development:

“The gray matter of the brain consists of about 65% fat — 25% of that is cholesterol. White matter, the myelin sheaths, is 75–85% fat, dominantly saturated fat and omega-3 and omega-6 fatty acids.”

That’s not something plant-based formulas can replicate. Despite years of industrial attempts to engineer better substitutes, no infant formula comes close to matching breast milk’s composition, which is rich in:

• Saturated fats (especially palmitic acid)
• Cholesterol
• DHA and EPA (critical omega-3 fatty acids)
• Vitamins A, D, E, K
• Galactose (instead of fructose)
• Minimal polyunsaturated fatty acids

Formula, influenced by decades of flawed dietary guidelines, often replaces saturated fats with high amounts of vegetable oils, sugars, and synthetic additives — a shift Dr. Cywes warns is dangerous:

“Modern humans, when they design formulas, believe they are better than God in nature… Instead of using breast milk as a template, they clashed with it.”

The Brain’s Explosive Demand for Fat

From the fourth week of gestation to age five, the human brain undergoes rapid structural development. It is an energy-intensive process: in newborns, up to 75% of all energy is devoted to the brain.

“At birth, 35–40% of brain fat must come through consumption — from breast milk or real food.”

Breast milk provides this in the exact ratios needed. It’s rich in:

• Palmitic acid, a 16-carbon saturated fat foundational for phospholipids
• Odd-chain fatty acids, like C15 and C17, uniquely found in breast milk
• Conditionally essential omega-3 fatty acids (DHA and EPA) that infants can’t synthesize fast enough on their own

This fat-centric nutrient profile fuels not only energy demands, but the structural assembly of neural membranes, myelin sheaths, and signaling systems.

Breastfeeding, Autism, and the Metabolic Theory

The decline in breastfeeding — especially exclusive breastfeeding — may be a key contributor to the rising rates of autism spectrum disorder (ASD). Dr. Cywes highlights a striking finding:

“A meta-analysis showed that ASD children had a significantly lower incidence and shorter duration of breastfeeding than children with typical development (1).”

This correlation is not coincidental. According to Dr. Cywes, autism is a disease of “structural brain maldevelopment” caused by disrupted metabolic and hormonal conditions in utero and infancy. These disruptions are driven by:

• Maternal hyperglycemia (often due to gestational diabetes)
• High carbohydrate, low-fat diets
• Reduced availability of ketones and essential fatty acids to the fetus
• Formula feeding that lacks adequate fat, cholesterol, and DHA

A 2014 study found that if gestational diabetes occurred before 26 weeks of pregnancy, the absolute risk of ASD was 42% — nearly 1 in 2 children (2).

Hormonal Cycling and the Infant Brain

Breastfeeding also supports hormonal balance. Post-meal insulin and between-meal glucagon cycles regulate substrate availability to the brain. In the absence of this natural hormonal cycling — caused by constant carbohydrate intake and frequent snacking — metabolic chaos ensues:

“Persistent hyperinsulinemia eliminates ketones as a brain substrate and disrupts lipid assembly in the brain. That causes structural brain maldevelopment, particularly of white matter.”

By contrast, breast milk — especially when produced by a mother following a well-formulated low-carb, high-fat diet — supports the ketone-glucose balance critical to neurodevelopment.

Beyond Calories: Breastfeeding Is an Emotional and Structural Anchor

Dr. Cywes reminds us that breastfeeding is not just about nutrients — it is a regulator of behavior, emotion, and circadian rhythms. Breastfeeding sets the stage for metabolic and hormonal predictability, supporting:

• Autonomic nervous system regulation
• Emotional development
• Appetite signaling and satiety (resisting overeating)

Formula Feeding: Proceed With Caution

While breastfeeding remains ideal, Dr. Cywes acknowledges that some mothers cannot breastfeed. In those cases, he advocates for formulas that mimic the high-fat, low-carb profile of breast milk as closely as possible.

“If the formula you’re using has 75–80% of the calories from fat, you will significantly reduce the risk of ASD, epilepsy, and cognitive dysfunction.”

Breast is best — but if formula is necessary, ketogenic formulas are the next best alternative.

Supporting the Mother: A Crucial Ingredient

Breastfeeding success depends heavily on maternal health. Dr. Cywes emphasizes maternal preparation well before conception:

“The optimal well-being of a mother and baby occurs when pregnant mothers follow a well-formulated, low-carbohydrate, high-fat, intermittent fasting ketogenic diet.”

Maternal insulin sensitivity and nutrient sufficiency (especially DHA, folate, ADEK, iodine, and salt) directly impact breast milk quality and fetal neurodevelopment.

Equally important is mental health support postpartum. Watch for signs of postnatal depression, which can compromise breastfeeding capacity and bonding.

Infant Nutrition Timeline: From Breast to Table

Dr. Cywes offers a powerful roadmap for evolutionarily consistent infant feeding:

0–6 months:

• Exclusive breastfeeding
• Maternal diet: low-carb, high-fat, with added DHA, vitamin D3/K2, iodine, salt

Between 4 and 6 months to 1 year:

• Continue breastfeeding or ketogenic formula
• Begin by introducing high-fat, animal-based real foods (e.g., egg yolks, liver pâté, pureed fish, avocado, butter, tallow). Breastfed babies’ iron stores run out by 6 months, indicating the importance and appropriateness of introducing animal-based iron-containing real foods at this stage

“Vegetables, real fats, whole or fermented milk (preferably goat’s milk) and limited whole fruit can also be introduced during this stage, systematically, one-at-a-time,” adds registered dietitian, Tamzyn Murphy.

12+ months:

• Continue breastfeeding if appropriate for the mother and child in question
• Water and whole and fermented milk (preferably goat’s milk)
• Avoid fruit juices, sweetened snacks, grains, and seed oils
• Encourage structured meal times (no grazing or snacking)

“Feed your baby what you eat. Don’t buy baby food. A ribeye steak is better than a rice cereal.”

Breastfeeding Is Brain Protection

In conclusion, breastfeeding is not just an act of nourishment — it is a metabolic intervention, a neurodevelopmental safeguard, and a legacy of human evolution. Dr. Cywes makes the case unequivocally:

“Breastfeeding for as long as possible is critical. Breast milk quality is highest when the mother follows a low-carbohydrate, high-fat diet. That is how we protect brain development and prevent autism.”

Let World Breastfeeding Week 2025 be a wake-up call. The stakes are high — and the solution is ancient.

Nutrition Network Supports Breastfeeding and Brain Health

At Nutrition Network, we advocate for evolutionarily consistent infant nutrition — and we believe breastfeeding is the cornerstone. Through education and clinical training, we empower healthcare professionals to guide mothers in supporting their baby’s brain development through real food, healthy fats, and metabolic health.

👉 Join our Ketogenic: The Science and Practice of Therapeutic Carbohydrate Restriction training to deepen your understanding of metabolic nutrition in pregnancy, infancy, and beyond.

Because breast is best — and nutrition is destiny.

References

1. Tseng, P.-T., Chen, Y.-W., Stubbs, B., Carvalho, A.F., Whiteley, P., et al. (2019). Maternal breastfeeding and autism spectrum disorder in children: a systematic review and meta‑analysis. Nutritional Neuroscience, 22(5), 354–362.

Xiang AH, Wang X, Martinez MP, et al. Association of Maternal Diabetes With Autism in Offspring. JAMA. 2015;313(14):1425–1434. doi:10.1001/jama.2015.2707