Breast Milk: Nature’s Superfood and How Your Body Makes It

Breastfeeding mother

Breast milk is often called "liquid gold" — and for good reason. It’s a living, dynamic substance that not only nourishes your baby but adapts in real time to their needs. But have you ever wondered exactly what’s in breast milk and where it all comes from?

In this article, we’ll explore the fascinating science behind the components of breast milk, how your body produces it, and why it’s the perfect start for your baby’s life.

How Is Breast Milk Made?

Your body begins preparing for breastfeeding during pregnancy. From around 16 weeks gestation, the alveoli — small, grape-like clusters of cells in the breasts — start producing colostrum, the first milk.

After birth, when the placenta is delivered, hormone levels shift dramatically. The drop in progesterone and rise in prolactin trigger copious milk production — a process known as lactogenesis II.

Milk is produced in the alveoli and travels through tiny ducts to the nipple, where it is drawn out by your baby’s suckling. The process is largely driven by prolactin (milk-making hormone) and oxytocin (responsible for the let-down reflex).

What’s In Breast Milk?

Breast milk is far more than just food. It’s a complete system of nutrition, hydration, immune protection, and development support — and it changes constantly depending on your baby's age, health, and feeding patterns.

1. Water (87%)

Breast milk is around 87% water, ensuring your baby stays fully hydrated — even in hot weather — without needing extra water.

2. Carbohydrates (Mainly Lactose)

Lactose is the primary carbohydrate in breast milk. It:

• Provides energy

• Supports the growth of healthy gut bacteria (the infant microbiome)

• Aids in calcium absorption

3. Fats (3-5%)

Fats are essential for:

• Brain and nervous system development

• Energy and healthy weight gain

• Vitamin absorption (A, D, E, and K are fat-soluble)

Fats in breast milk change feed to feed — with higher fat content in hindmilk (later in the feed). The type of fat is also influenced by your diet.

4. Proteins (0.8-0.9%)

Breast milk proteins are perfectly designed for easy digestion and growth:

• Whey and casein in ideal balance

• Contain lactoferrin, which binds iron and has antimicrobial properties

• Includes enzymes that help digestion and nutrient absorption

5. Vitamins & Minerals

Breast milk provides essential vitamins and minerals, including:

• Vitamin A (for eye health and immunity)

• Vitamin D (levels depend on maternal stores or supplementation)

• Iron (though small amounts, it’s highly bioavailable)

• Calcium, zinc, and selenium for bone development and immune function

6. Immune Factors

This is where breast milk really shines. It contains:

• Antibodies (especially secretory IgA) — coats your baby’s gut and protects against infections

• White blood cells — yes, living immune cells are present in your milk

• Cytokines and anti-inflammatory agents to support immunity and healing

• Oligosaccharides (HMOs) — special sugars that feed beneficial bacteria and protect against pathogens

7. Hormones

Breast milk contains hormones that help regulate your baby’s growth and development, including:

• Leptin and adiponectin (involved in appetite regulation and metabolism)

• Melatonin (higher levels at night to help baby settle and sleep)

Where Do These Components Come From?

Your body creates breast milk by drawing on:

✅ Maternal nutrient stores — Your body will prioritise your baby’s needs, pulling from your own reserves of calcium, iron, and vitamins.

✅ Your diet — The composition of certain fats and vitamins (like Vitamin D and DHA) in breast milk can be influenced by what you eat. A varied, nutrient-dense diet helps support both you and your baby.

✅ Your immune system — If you encounter viruses or bacteria, your immune system produces antibodies that are passed through breast milk to protect your baby.

✅ Your baby’s needs — Remarkably, when your baby breastfeeds, their saliva interacts with your nipple, sending signals that can influence the composition of your milk, tailoring it to their health and stage of development.

Did You Know? Interesting Facts About Breast Milk

✔ The colour of breast milk can change — it may appear yellowish (colostrum), bluish (foremilk), or creamier (hindmilk).
✔ Preterm milk differs from term milk — it’s higher in certain proteins and nutrients to meet the needs of a premature baby.
✔ Your breast milk contains stem cells that can help repair and grow tissue in your baby’s body.

Conclusion

Your breast milk is an incredible, living substance designed to nourish, protect, and support your baby’s growth and development. It’s made from a combination of your nutrient stores, diet, hormones, and immune system responses, adapting continuously to meet your baby’s needs.

If you're breastfeeding, know that your body is working intelligently to deliver exactly what your baby needs — every feed, every day.