What’s In Breast Milk and What’s In Formula?

What's In Breast Milk and What's In Formula?

Ever been curious as to what’s found in breast milk and what ingredients can be found in formula?

Developed by the Douglas College for the Breastfeeding Course for Health Care Providers, this eye opening comparison of breast milk ingredients and formula ingredients is astounding.

Please understand that this article has not been published so formula feeding mothers can feel guilty.

Nor has it been posted for anyone to feel superior.

BellyBelly often acknowledges that there are plenty of valid reasons why parents formula feed their babies and we support them.

We also understand that some things can be hard to hear when we’ve not come to peace with them.

This article contains important information that we need to know — it’s science, biology and healthcare all in one. It’s even more important to hear for those who have a choice and are researching what to feed their baby.

With information comes education, and with both of those things, it gives you power and options. BellyBelly is dubbed “The Thinking Woman’s Website” because it’s written especially for parents who want to know more than marketing hype when making choices and decisions — just as I did as a young mother. So if you feel you may be offended, please do not read any further.

What’s In Formula Milk?

Firstly, please note that formulations change over time — ingredients and compositions may be a little different to the below list. There are also a range of formulas on the market to cater for different needs. For example, there are hypoallergenic formulas, soy formulas and more. So this is a general indication of what might typically be found in a formula ingredient list.

For more information about the differences between different formulas — for example organic, soy, hypoallergenic and others — see our article, choosing baby formula – 5 facts you need to know.

Formula Ingredients



  • Lactose
  • Corn maltodextrin


  • Partially hydrolyzed reduced minerals whey protein concentrate (from cow’s milk)


  • Palm olein
  • Soybean oil
  • Coconut oil
  • High oleic safflower oil (or sunflower oil)
  • M. alpina oil (Fungal DHA)
  • C.cohnii oil (Algal ARA)


  • Potassium citrate
  • Potassium phosphate
  • Calcium chloride
  • Tricalcium phosphate
  • Sodium citrate
  • Magnesium chloride
  • Ferrous sulphate
  • Zinc sulphate
  • Sodium chloride
  • Copper sulphate
  • Potassium iodide
  • Manganese sulphate
  • Sodium selenate


  • Sodium ascorbate
  • Inositol
  • Choline bitartrate
  • Alpha-Tocopheryl acetate
  • Niacinamide
  • Calcium pantothenate
  • Riboflavin
  • Vitamin A acetate
  • Pyridoxine hydrochloride
  • Thiamine mononitrate
  • Folic acid
  • Phylloquinone
  • Biotin
  • Vitamin D3
  • Vitamin B12


  • Trypsin

Amino acid

  • Taurine
  • L-Carnitine (a combination of two different amino acids)


  • Cytidine 5-monophosphate
  • Disodium uridine 5-monophosphate
  • Adenosine 5-monophosphate
  • Disodium guanosine 5-monophosphate

Soy Lecithin (an emulsifier)

When choosing formula for your baby, make sure you read the labels and choose a lower protein formula. A recent study has found that many formulas are being made on the higher acceptable limits of protein, which may be an explanation of the link between formula and childhood obesity. Read what you need to consider when buying formula here.

What’s In Breast Milk?

Here is a summary of what ingredients can be found in breast milk.

Breast Milk Ingredients


Carbohydrates (energy source)

  • Lactose
  • Oligosaccharides (see below)

Carboxylic acid

  • Alpha hydroxy acid
  • Lactic acid

Proteins (building muscles and bones)

  • Whey protein
  • Alpha-lactalbumin
  • HAMLET (Human Alpha-lactalbumin Made Lethal to Tumour cells)
  • Lactoferrin
  • Many antimicrobial factors (see below)
  • Casein
  • Serum albumin

Non-protein nitrogens

  • Creatine
  • Creatinine
  • Urea
  • Uric acid
  • Peptides (see below)

Amino Acids (the building blocks of proteins)

  • Alanine
  • Arginine
  • Aspartate
  • Clycine
  • Cystine
  • Glutamate
  • Histidine
  • Isoleucine
  • Leucine
  • Lycine
  • Methionine
  • Phenylalanine
  • Proline
  • Serine
  • Taurine
  • Theronine
  • Tryptophan
  • Tyrosine
  • Valine
  • Carnitine (amino acid compound necessary to make use of fatty acids as an energy source)

Nucleotides (chemical compounds that are the structural units of RNA and DNA)

  • 5’-Adenosine monophosphate (5”-AMP)
  • 3’:5’-Cyclic adenosine monophosphate (3’:5’-cyclic AMP)
  • 5’-Cytidine monophosphate (5’-CMP)
  • Cytidine diphosphate choline (CDP choline)
  • Guanosine diphosphate (UDP)
  • Guanosine diphosphate – mannose
  • 3’- Uridine monophosphate (3’-UMP)
  • 5’-Uridine monophosphate (5’-UMP)
  • Uridine diphosphate (UDP)
  • Uridine diphosphate hexose (UDPH)
  • Uridine diphosphate-N-acetyl-hexosamine (UDPAH)
  • Uridine diphosphoglucuronic acid (UDPGA)
  • Several more novel nucleotides of the UDP type


  • Triglycerides
  • Long-chain polyunsaturated fatty acids
  • Docosahexaenoic acid (DHA) (important for brain development)
  • Arachidonic acid (AHA) (important for brain development)
  • Linoleic acid
  • Alpha-linolenic acid (ALA)
  • Eicosapentaenoic acid (EPA)
  • Conjugated linoleic acid (Rumenic acid)

Free Fatty Acids

Monounsaturated fatty acids

  • Oleic acid
  • Palmitoleic acid
  • Heptadecenoic acid

Saturated fatty acids

  • Stearic
  • Palmitic acid
  • Lauric acid
  • Myristic acid


  • Phosphatidylcholine
  • Phosphatidylethanolamine
  • Phosphatidylinositol
  • Lysophosphatidylcholine
  • Lysophosphatidylethanolamine
  • Plasmalogens


  • Sphingomyelin
  • Gangliosides
  • GM1
  • GM2
  • GM3
  • Glucosylceramide
  • Glycosphingolipids
  • Galactosylceramide
  • Lactosylceramide
  • Globotriaosylceramide (GB3)
  • Globoside (GB4)


  • Squalene
  • Lanosterol
  • Dimethylsterol
  • Methosterol
  • Lathosterol
  • Desmosterol
  • Triacylglycerol
  • Cholesterol
  • 7-dehydrocholesterol
  • Stigma-and campesterol
  • 7-ketocholesterol
  • Sitosterol
  • β-lathosterol
  • Vitamin D metabolites
  • Steroid hormones


  • Vitamin A
  • Beta carotene
  • Vitamin B6
  • Vitamin B8 (Inositol)
  • Vitamin B12
  • Vitamin C
  • Vitamin D
  • Vitamin E
  • a-Tocopherol
  • Vitamin K
  • Thiamine
  • Riboflavin
  • Niacin
  • Folic acid
  • Pantothenic acid
  • Biotin
  • Minerals
  • Calcium
  • Sodium
  • Potassium
  • Iron
  • Zinc
  • Chloride
  • Phosphorus
  • Magnesium
  • Copper
  • Manganese
  • Iodine
  • Selenium
  • Choline
  • Sulpher
  • Chromium
  • Cobalt
  • Fluorine
  • Nickel


  • Molybdenum (essential element in many enzymes)

Growth Factors (aid in the maturation of the intestinal lining)


  • interleukin-1β (IL-1β)
  • IL-2
  • IL-4
  • IL-6
  • IL-8
  • IL-10
  • Granulocyte-colony stimulating factor (G-CSF)
  • Macrophage-colony stimulating factor (M-CSF)
  • Platelet derived growth factors (PDGF)
  • Vascular endothelial growth factor (VEGF)
  • Hepatocyte growth factor -α (HGF-α)
  • HGF-β
  • Tumor necrosis factor-α
  • Interferon-γ
  • Epithelial growth factor (EGF)
  • Transforming growth factor-α (TGF-α)
  • TGF β1
  • TGF-β2
  • Insulin-like growth factor-I (IGF-I) (also known as somatomedin C)
  • Insulin-like growth factor- II
  • Nerve growth factor (NGF)
  • Erythropoietin

Peptides (combinations of amino acids)

  • HMGF I (Human growth factor)
  • Cholecystokinin (CCK)
  • β-endorphins
  • Parathyroid hormone (PTH)
  • Parathyroid hormone-related peptide (PTHrP)
  • β-defensin-1
  • Calcitonin
  • Gastrin
  • Motilin
  • Bombesin (gastric releasing peptide, also known as neuromedin B)
  • Neurotensin
  • Somatostatin

Hormones (chemical messengers that carry signals from one cell, or group of cells, to another via the blood)

  • Cortisol
  • Triiodothyronine (T3)
  • Thyroxine (T4)
  • Thyroid stimulating hormone (TSH) (also known as thyrotropin)
  • Thyroid releasing hormone (TRH)
  • Prolactin
  • Oxytocin
  • Insulin
  • Corticosterone
  • Thrombopoietin
  • Gonadotropin-releasing hormone (GnRH)
  • GRH
  • Leptin (aids in regulation of food intake)
  • Ghrelin (aids in regulation of food intake)
  • Adiponectin
  • Feedback inhibitor of lactation (FIL)
  • Eicosanoids
  • Prostaglandins (enzymatically derived from fatty acids)
  • PG-E1
  • PG-E2
  • PG-F2
  • Leukotrienes
  • Thromboxanes
  • Prostacyclins

Enzymes (catalysts that support chemical reactions in the body)

  • Amylase
  • Arysulfatase
  • Catalase
  • Histaminase
  • Lipase
  • Lysozyme
  • PAF-acetylhydrolase
  • Phosphatase
  • Xanthine oxidase

Antiproteases (thought to bind themselves to macromolecules such as enzymes and as a result prevent allergic and anaphylactic reactions)

  • a-1-antitrypsin
  • a-1-antichymotrypsin

Antimicrobial factors (used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses)

  • Leukocytes (white blood cells)
  • Phagocytes
  • Basophils
  • Neutrophils
  • Eoisinophils
  • Macrophages
  • Lymphocytes
  • B lymphocytes (also known as B cells)
  • T lymphocytes (also known as C cells)
  • sIgA (Secretory immunoglobulin A) (the most important antiinfective factor)
  • IgA2
  • IgG
  • IgD
  • IgM
  • IgE
  • Complement C1
  • Complement C2
  • Complement C3
  • Complement C4
  • Complement C5
  • Complement C6
  • Complement C7
  • Complement C8
  • Complement C9
  • Glycoproteins
  • Mucins (attaches to bacteria and viruses to prevent them from clinging to mucousal tissues)
  • Lactadherin
  • Alpha-lactoglobulin
  • Alpha-2 macroglobulin
  • Lewis antigens
  • Ribonuclease
  • Haemagglutinin inhibitors
  • Bifidus Factor (increases growth of Lactobacillus bifidus – which is a good bacteria)
  • Lactoferrin (binds to iron which prevents harmful bacteria from using the iron to grow)
  • Lactoperoxidase
  • B12 binding protein (deprives microorganisms of vitamin B12)
  • Fibronectin (makes phagocytes more aggressive, minimizes inflammation, and repairs damage caused by inflammation)
  • Oligosaccharides (more than 200 different kinds!)

Summing It All Up

That’s quite a lot to digest — pardon the pun! So to make sense of it all, I asked BellyBelly’s International Board Certified Lactation Consultant (IBCLC), Renee Kam, what she believes to be the most important ingredients in breast milk. We all know that breast milk is known for it’s protective and immune supporting properties — Renee reinforced this with her response. She says:

“Breastmilk contains the right balance of probiotics and prebiotics that human babies need to colonise their bowels with a healthy bacteria. Perhaps the most important anti-infective factor in breastmilk is an antibody called secretory IgA (sIgA). SIgA helps protect a baby from pathogens he is most likely to come across in the environment he lives in (we called this ‘targeted protection’). Breastfed babies may have asymptomatic infections (that don’t show any signs of inflammation) because of the anti-inflammatory factors in breastmilk, which can turn acute-inflammatory cells (e.g. neutrophils) off.”

The fats in breast milk are very important too.

“Of the fats in breastmilk, 88% are made from long-chain fatty acids. It’s these long-chain fatty acids (e.g. omega 3 fatty acids, especially DHA) that are constituents of brain and nerve tissue, and are needed in early life for mental and visual development.”

Finally, the self adjusting properties of breast milk are important too — a mother’s breast milk is custom made for her baby, based on the baby’s age and needs at the time. Renee says:

“The breastmilk a mother makes for her baby is different on day one, to day seven, to day 30, and so on. For example, the breastmilk made by a mother of a premature baby has different concentrations of various substances to suit her baby’s special needs. And, when weaning, a mother’s breastmilk increases the concentration of immune protective factors to give her baby a final dose of immune protection before weaning is complete.”

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Kelly Winder is the creator of BellyBelly.com.au, a writer, doula (trained in 2005), and a mother of three awesome children. She's passionate about informing and educating fellow thinking parents and parents-to-be, especially about all the things she wishes she knew before she had her firstborn. Kelly is also passionate about travel, tea, travel, and animal rights and welfare. And travel.


  1. Do you think the contents change based on the mothers diet? What if she doesn’t take a prenatal vitamin? Great article!

    1. According to many articles I’ve read a mother does not need to take vitamins to boost the nutrition in her milk. Nor does she need to change or follow a particular healthy diet. Breastmilk makes its own nutrients. BUT- i am very very vitamin d deficient and because of that i have to take my vitamins and give my son a dose as well for the first 3 months of his life. Breastmilk truely truely is liquid gold! Water is most important to keep you hydrated. Other than that, your milk is of perfect standard.

    2. Your body will take away from itself what it needs for the breast milk before it lacks anything for the baby. It is one of the reasons some moms suffer from cavities for the first time during pregnancy and bfeeding. But, you’re diet does boost whatever your baby is getting.

    3. I wouldn’t imagine it would change. Breastmilk is made to sustain human life even during things like famine. If a mother doesn’t take a prenatal her body will give nutrients first to her milk and then to the rest of her. Basically a mother would lack the nutrients she would need in her own body before her milk would lack it.

    4. I dont think the content will be much different based on mother diet. But it may effect the quantity/percentage of each content.

    5. Thank you, what an amazing article, a great read, I’m glad I sought breastfeeding help when I needed it, I’m a happy breastfeeding mama 3 times over and I’m proud to know more about the make up of my milk, thanks ☺

  2. I love this article. Although I exclusively breastfeed I’ve often wondered how different breast milk is from formula.

  3. Hi, I’m tandem nursing my two girls. 22mo and 2mo. It says in the article that breastmilk is made to suit the baby’s needs. So what happens when u are nursing both a 2 month old n an almost 2yo toddler?

    1. The baby’s saliva let’s your breasts know what milk it needs and will make the milk that that baby needs (Be it newborn or toddler). It is fascinating!! Well done for tandem feeding, that is incredible!!

    2. It adjusts to the child feeding. Breasts are very clever & can tell from the saliva what is needed for that child. If you exclusively used one breast per child then pumped, you’d see the difference in milk (different fat/water content).

  4. Thank you so much for this article as i’m expecting a baby boy soon and wasn’t sure if i should breast feed or not atleast now i know…

  5. I was not able to breastfeed since I gave birth(March 17,2015) because my nipples not exist even I used breastpump,is there anything to worry about in using formula or bottle feeding for my baby?

    1. I really wanted to breastfeed but wasn’t able to due to nipple problems. I tried various gadgets but I couldn’t do it so ended up giving my baby a mix of formula and expressed milk. I felt like a failure as I didn’t breastfeed but my baby is almost two and is perfectly healthy and doesn’t appear to be different to his friends who were breastfed. Some may say it is too early to say but look at the people you know who weren’t breastfed compared to those who weren’t and I think you’ll see that there aren’t big differences. Breastmilk is obviously what is meant for babies and formula may be second best but perhaps it is a close second.

      1. I am a nearly 70 year old woman, entirely formula fed as a baby and hardly ever ill in my life, nevr seriously. The world is full of artifically fed healthy people. I breastfed all four of my children – the first two for a few months and the last two for several years. To me it is nonsense to deny the amazing, and totally human-adapted nature of breast milk simply because so many babies don’t get it, or don’t get it for long. The more we discover about it, the more wonderful we learn it is. Better information an d support and a breastfeeding-friendly environment would help more mothers nurse their babies. Blame the soxiety we live in and not yourselves if breastfeeding doesn’t go as well as you’d hoped. If you are struggling, though, it is worthwhile seeking effective help to reach your goals. Breastfeeding ought to be joyful not distressing.

  6. The pre and probiotic factors of early breast milk help establish healthy bacteria in the baby’s gut, therefore any amount if early nursing is beneficial. If you have tried breastfeeding and then had it not work out for one reason or another, then the baby still had this benefit. Trying out nursing is a good option, just to see if it works for you, and get the baby those early benefits.

  7. Can you breastfeed while pregnant and then start breastfeeding the new baby after the baby is born and will the breast milk be different cause ive heard breast milk changes as baby grows, and I know when you first start you have colustrum which the Dr’s called liquid gold and that it’s very important for baby and beneficial. If you already have milk you won’t have colustrum right? And would that be a problem for the baby? Or is it just important that the baby is getting breast milk? Sorry for so many questions…..

    1. I breastfeed my first daughter for the first 10 weeks of pregnancy with my second daughter. (She was two weeks shy of her 2nd birthday when we stopped) I only stopped because my nipples were very sensitive and it was painful for me to keep nursing.
      I believe it is around that time in pregnancy where the milk changes back to colostrum which is a saltier taste to full milk so often mothers find the older sibling self-weans, but I believe unless your dr/midwife has told you otherwise it is considered safe to continue to nurse the older child during pregnancy.

    2. I am currenlty still nursing my son at 34 wks pregnant. Your body will still produce colostrum. In fact my milk transitioned into colostrum aroound 20wks.

    3. I was unable to continue breastfeeding while pregnant. At 2 months along I started getting regular migraines – I assume this was my bodies way of saying I just didn’t have the nutrients for all 3 of us and it was 1 week after my others 1st birthday so nursing was already a limited part of her diet (twice a day) – so really watch your diet and make sure you’re still getting enough nutrients for yourself.

  8. Why does my breast milk make my baby tired ? Every time he has it he falls asleep during a feeding and doesn’t finish his bottle I give him 3 ounces

    1. This is actually a really cool biological benefit of breastfeeding, and as with all other aspects of breastfeeding, it is intentionally designed this way. Breastmilk contains an amino acid called tryptophan (listed above) which is used by our bodies to create melatonin, which is used to induce and regulate sleep. During times when moms is feeling tired, and in the evening, moms milk actually contains more of these sleep-inducing properties for baby, all in an effort to give tired mama more rest! With newborns, it is important to make sure that they are getting enough milk, of course (and we can monitor wet and dirty diaper output and wake baby more often if needed), but as babies get older, they are able to perfectly regulate how much milk they take in at a time. 3 ounces is plenty for most babies. Their bellies are small, and they are designed to take in small amounts of breastmilk frequently (remember that time at the breast isn’t only about nutrition, it’s about communicating with mom, bonding, temperature regulation, and more).

    1. While baby does communicate information to mom through saliva at the breast, mom also takes in information from baby in other ways, like kissing and breathing in the pathogens, etc. on babies body.

  9. Fascinating. Would have been significantly more interesting if all the ingredients had been explained, rather than just a long list of words, many of which mean nothing to most people.
    And exactly how different are the things in formula to the things in breast milk? Obviously formula does an excellent job at nourishing a baby, so they can’t be totally different.

    1. Hannah, as our IBCLC explained at the end, the most significant factor is the huge difference in anti-infective factors which protect babies from illness, as well as a vast range of probiotics.

      We did try to explain where we could in the headings, e.g.:

      Hormones (chemical messengers that carry signals from one cell, or group of cells, to another via the blood)
      Growth Factors (aid in the maturation of the intestinal lining)
      Antimicrobial factors (used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses)

      I think another of the stand out observations is that breastmilk is a very complex, living thing which changes and adapts. It’s huge list of ingredients has a wide range of functions, which would be impossible to replicate with formula.

    1. Often you can simply feel like you don’t. I had this feeling often with all 3 kidos, but stuck with it anyways.

      Optionally, though keep in mind the risks to your supply, you can nurse first and then top up with formula after each feeding.

  10. What if you exclusively pump? Does the breast milk still change according to the baby’s age and needs even though the baby doesn’t latch on? Does pumping affect the factors in the breast milk?

  11. I honestly presued breast feeding because of being on such a tight budget. That was a decision I made the moment I got pregnant, it wasn’t until later in my pregnancy that I did more research and truly appreciate my decision. I breast fed for 18 months then my busy boy didn’t have time for that and weened himself

  12. I know it’s only a big deal to me because I don’t get to leave the house for long and have that bond with my daughter, but it still makes me so sad/angry I ended up exclusively pumping after only 1 month because she had a tongue-tie the doctors ignored leading to a poor latch and inefficient removal. lactation consultants and such in America are a joke.

    1. It’s never to late to get baby on the breast, if that’s something you’re interested in! They can learn, even at a later age. My baby didn’t latch for over six weeks (I exclusively pumped until then), and I’ve heard success stories of older babies transitioning from bottle to breast! I agree that there is a lack of lactation support for moms in America. I was so lucky that my OB is also an LC and she was a phenomenal advocate and help for me and my baby!! Of course, there is nothing wrong with exclusively pumping, you are doing an incredible thing for your baby!! Great job, mom!!

  13. I am currently still breastfeeding my second daughter who is 9 months old. I have had two open cuts on my breasts for the last three months. Didn’t have a problem prior to this apart from soreness for a few weeks after she was born.
    I use my milk as well as the usual methods to heal but still they are open wounds

  14. As a father, it is a hard conversation to have. I guess I don’t have much skin in the game because I’m not the one who has to have our beautiful daughter stuck on my nipple for hours each day but now my wonderful wife wants to supplement her breastfeeding with some formula feeds. It is certainly not my preference as I firmly believe breastfeeding is best although I have no idea how to assert my view without an imminent argument. All opinions welcome. 🙂

  15. What the article doesn’t mention is that breastmilk also contains traces of heavy metals and other toxins from the mother’s diet and released from mum’s adipose tissue where they’ve been stored from a lifetime of consumption… I’m not at all against breastfeeding, I breastfed both my sons and would *always* advocate breastfeeding when it’s possible but this information might show that there actually are some cons to breastfeeding not just PROs! and might just help those mum’s who had to formula feed get a little bit of comfort that there is a pro to formula feed. On the whole I still feel breastfeeding is best although I have heard one scientist claim that it would be safer for all babies to be formula fed (I disagree with this as do most other experts!). However, It definitely highlights the importance to human society to tackle pollution and heavy metal exposure etc and importance of all young women to follow low toxin diets to avoid accumulation of toxins and not to lose *too* much weight during breastfeeding!

  16. Great article!
    Thank you for listing….it’shows truly shows how wonderful and amazing breast milk is!!!
    I feel fortunate and proud to have been able to breastfeed my multiples for lost 2 and a half years!

    Regarding the ingredients for formula milk….as you have said, it is important not to make mothers who give formula milk feel guilty or bad or as though they are doing something wrong (including those who also breastfeed).
    There is a growing trend to pass on misinformation suggesting that formula milk actually harms babies.
    As someone in a position to inform, please could you confirm which ingredients of formula milk that you have listed cause harm and if you agree with me that formula milk doesn’t harm babies, please could you make this just as clear in order to dispelled potentially dangerous misinformation?

    Thank you very much.

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