Breast milk and formula milk: what’s the difference?

Decisions around feeding your baby are determined by a combination of factors unique to each family and situation. One of the factors to consider when making your decision is the differences and similarities between human milk and formula milk.

Here is a brief overview:

Breastmilk (human milk) is a living fluid. Your body is constantly assessing your baby’s needs and will change your milk in response. E.g.

• Within 20 minutes of someone sneezing near you and your baby, your body will have put antibodies to protect baby from those pathogens into your milk
• Your body puts more melatonin (sleep hormone) into your milk at night-time
• On hot days your body will increase the water content of your milk to keep baby hydrated
• As your baby’s growing body needs more nutrients, your body puts more nutrients into the same amount of milk
• As your baby becomes mobile and more likely to come into contact with germs, your body puts more immune factors into your milk to protect them

Visit the human-milk website for more information on the constituents of human milk.

Formula is a nutritional substitute which is strictly regulated and standardised, it provides the basic nutrients needed but cannot change in response to your baby’s needs. E.g.

• As your baby needs more nutrients, you will need to increase the amount of formula given to meet these
• On hot days, your baby may need to be offered additional water to keep them hydrated
• Formula does not offer any immune support to help baby fight off infections and there are some constituents of breastmilk which are impossible to replicate in formula.

Visit the First Steps Nutrition website or the Infant Milk Association website for more information on infant formula.

Remember that feeding your baby doesn’t have to be all or nothing! You can combination (mixed) feed your baby, with both breast milk and formula.

Research shows that any amount of human milk (even 5ml a day) can share your immune system to help baby fight off infections as well as provide factors such as lactoferrin to help baby digest the nutrients in formula milk. The more breast milk baby receives, the greater the impact of these immune and metabolic factors.