The Trust

What is the difference between breast milk and formula milk?

Breast milk

Breast milk is tailor made for human babies. It contains water, fat, protein, carbohydrate, minerals and vitamins and other important factors that are absent from infant formula. It contains hormones, enzymes, growth factors, essential fatty acids, as well as proteins that support your baby’s immune system known as immunoglobulins.

These protect your baby against some illnesses that you have had in the past and some viruses that you come into contact with when you are feeding. The make-up of a mother’s milk changes from feed to feed, adapting to the needs of her baby as they grow and providing just the right amount for them.

Infant formula milk

Infant formula milk is made from cow’s milk which has been processed to make it “suitable” for babies. (Formula may also contain, among other things, soya protein, structured vegetable oils and inositol, antioxidants and fish oils). There are several brands of infant formula and different types e.g. first milk, second milk, follow–on milk, etc. If you choose to use infant formula you need to be very careful about which type of milk you use as this could affect your baby’s health. Always read the labels very carefully. 

Practical considerations

Breast milk

Breast milk is the ultimate convenience food. There is no preparation and sterilizing to be done. It is stored at the right temperature and once you and your baby have got used to it, you can feed anytime, anyplace anywhere! Plus it’s free! Once breastfeeding is established (usually after the first couple of weeks) you can express your milk to be given to your baby at the times when you are not together.

Infant formula milk

Powdered infant formula milk is not a sterile product, therefore, for safety reasons, it is very important that each feed is made up fresh when your baby wants to feed. This means forward planning when you are going out with your baby as equipment is required. If you go out without your baby, you’ll need to ensure you have shown the carer how to prepare feeds correctly. 

Baby’s digestion

Breast milk is designed for your baby’s developing digestive system and is easily digested. The protein and fat contained in it are used effortlessly by the body and the micro nutrients which are very important for health, are absorbed more easily. Breast milk has a natural laxative effect so your baby is less likely to suffer from constipation. Their stools are mustard coloured, very soft and are sweeter smelling!

Infant formula milk: is harder to digest so it sits in the stomach for longer. Babies are more prone to constipation. Stools are usually smellier than those of breastfed infants. Babies stools are usually firmer and they are more prone to constipation.

Health benefits for babies

Breastfed babies are less likely to develop infections such as Gastroenteritis (stomach infection), chest infections, ear infections and urinary tract (bladder) infections. Breast milk makes your baby’s digestive system more acidic which prevents harmful bacteria from growing thereby reducing the risk of infections. Growth factors promote the development of your baby’s immature digestive system helping to protect him or her against infections. Breast milk also contains the antibodies you have already produced and these will also protect your baby as required. Research shows breastfeeding also offers some protection against some childhood cancers, sudden infant death syndrome (cot death) and developing heart disease in later life. Good personal hygiene is always important how ever you feed your baby so before you feed your baby expressed breast milk care must be taken to sterilise any equipment.

Infant formula milk: Infant formula milk does not provide specific protection for your baby against illness. Care must be taken with the preparation and storage of formula milk to reduce the risk.  Ask your midwife or health visitor about this.

Breastmilk: may reduce the risk of your baby suffering from allergies as it is almost always tolerated well by a baby because it is tailor made by you, for your baby. Furthermore evidence suggests babies are less likely to develop asthma and eczema than those who receive infant formula milk.
Formula milk: No, there is no scientific evidence that babies are less likely to develop allergies.

Health benefits for mums

Breastfeeding: There are many short and long term health benefits for mums who breastfeed. You will get your shape back quicker as breastfeeding burns up to 500 calories a day and your womb shrinks back to its pre pregnant size more quickly which helps to reduce your blood loss. You will get a better sleep at night as you don’t need to get out of bed to make up a formula feed and you will find it easier to get back to sleep after a feed. In fact, breastfeeding helps you rest for periods throughout the day whether you feel you have the time or not. It gives you time to rest, catch up with friends or have a cuddle with your toddler.

There are numerous health benefits including reducing your risk of uterine, ovarian and breast cancer. It also reduces your risk of developing osteoporosis in later life and you are less likely to develop type two diabetes.

Infant formula: There are no health benefits for mum.


Breast milk: Research has shown that breastfed babies are less likely to be overweight than those given infant formula, even as they get older and have stopped breastfeeding. This is partly because the breastfed baby will feed until he is full and then stops, where as a formula fed baby can always be coaxed to take more than is required. This pattern of breastfeeding lays the foundation for a healthy eating habit for the rest of their life.

Infant formula milk: Does not provide any protection and in fact can be the foundation stone for being overweight. This is because a baby can often be persuaded to finish the bottle rather than stopping when they are satisfied, which can establish unhealthy eating patterns for the future.

Spending time with your baby

Breast milk: Only you can breastfeed your baby and to do this well you need to relax and enjoy your time together feeding. The bond you develop will be strong and lasting. Being a new mum can be tiring and it is very important that you take time out to rest and relax – you are not wonder woman! Breastfeeding give you the perfect opportunity to rest throughout the day which is what every new mum needs.

Infant formula milk: Feeding your baby with formula milk is often the first thing that others want to help with but it is still a special time for you to bond with your baby. Also, while someone else is feeding your baby you may well find yourself finding other tasks to do, rather than taking valuable time to rest.

Environmental issues

Breastmilk: production does not have adversely affect the environment as mothers do it naturally!

Formula milk: has a considerable environmental impact due to resources used to produce and deliver it to the store and the baby.

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