If you didn't already know, Humans are mammals.

Being mammals, we grow our offspring in the womb, and after birth, provide their sustenance via milk that is produced in the breasts of a female. Breast milk offers a brand new human everything they need to survive, from basic nutrients, to antibodies, and even disease fighting stem cells! This post will not go into the politics of breastfeeding, only what science says about what it is, and its short and long term benefits.

So what's in breast milk?

That's kind of a tricky question, because there are many types of breast milk, and each is a different cocktail. A mother will produce a special kind of milk for the first few days after giving birth, but even after her "mature"milk production begins, it will change depending on the diet of the mother, the time of day, and can even change in the middle of a feeding!

- Colostrum

This is the first milk a mother will produce. It is a bit thinner than regular milk, and is full of antibodies that will help build the infant's immune system. Colostrum also has a high protein concentration, and provides a newborn with many growth hormones that will boost its early development. In many mammals, fat concentration is higher in colostrum than in regular milk, though this is not the case with humans.
Newborn humans have a very sensitive and weak digestive system, and colostrum gives them high doses of things they need, with as little milk as possible. Colostrum also has a laxative effect, helping the infant quickly pass the byproducts of digestion.

Left: Colostrum / Right: Mature milk
Source

Over the following couple weeks, the milk produced will slowly transition into mature milk.

Mature human milk provides an infant with all the nutrition they need, including water, proteins, fat, and carbohydrates, as well as many vitamins and minerals like sodium, iron, calcium, and vitamins A, C, and D. Baby formula will provide all of these nutrients as well, and has been considered a safe and healthy alternative to breastfeeding for decades. There are, however, benefits to breast milk that even the most advanced formulas do not provide.

Breast milk contains over 600 species of live bacteria, most of which are beneficial to an infant's digestive and immune systems. It has been shown to contain endocannibinoids, which are the same type of neurotransmitter that are activated upon ingestion of cannabis. It also contains a simple sugar molecule that infant's aren't able to digest. This is food for the baby's gut bacteria, not the baby itself.

Benefits for mother and child

On top of the benefits provided by what's in the breast milk itself, breastfeeding can have many lasting benefits to both parties involved. The skin-to-skin contact that occurs during breastfeeding is shown to create a lasting bond between mother and child. Breastfeeding releases endorphins in the mother, relieving stress and helping to stimulate appetite. It can also lead to a reduced risk of Type 2 Diabetes, certain types of breast cancer, and ovarian cancer. The list of benefits includes a significantly reduced risk of childhood obesity, and death from infectious diseases within the first two years of life.

The long-term effects are a little less known, and a little harder to definitively conclude that these effects where the result of breastfeeding. However, many studies have been done that link breastfeeding to numerous long-term health benefits.

Reduced risk of obesity
Energy metabolism and protein intake are lower in breastfed infants versus those who were fed exclusively formula. It's thought that a higher protein intake leads to the production of insulin in larger amounts, which can lead to excess adipocytes.

Better blood pressure and reduced risk of type-2 diabetes
Breastmilk contains many long-chain polyunsaturated fatty acids (LCPUFAs), while most baby formulas do not. These fatty acids can help reduce blood pressure in adults. An infant's body isn't able to synthesize these fatty acids very well, so what they are getting from mom will set them up for a healthy blood flow. These same fatty acids are thought effect the skeletal muscle membrane, which can protect against insulin resistance.

Better total cholesterol
The high levels of cholesterol in breastmilk is thought to have a "programming" effect on blood cholesterol levels. Studies have shown that children who are breastfed grow up to have lower total cholesterol counts.

Increased cognitive function
Breastmilk can have a positive affect on intelligence due to those same LCPUFAs, which are crutial for cortical and retinal brain development. Studies show that breastfed children have a higher concentration of these fatty acids, and they have been positively linked to brain volume, and in male subjects, white matter.

These benefits where compiled by the World Health Organization, and you can read more in depth about all those studies HERE

Breast milk is the best thing a child can be fed during infancy. Again, formula is definitely a safe and health alternative, but the science says there are numerous benefits to breastfeeding if that is an option. I avoided going into reasons why some women aren't able or choose not to breastfeed, or any method of breastfeeding, as these can be red-button topics, and that's not what these Super Cool Science S#!t posts are about.

References:

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3586783/
• http://www.infantnutritioncouncil.com/resources/breastmilk-information/
• http://www.who.int/topics/breastfeeding/en/
• http://www.sciencedirect.com/science/article/pii/S1098882315300174?via%3Dihub
• https://www.womenshealth.gov/breastfeeding/making-decision-breastfeed
• https://www.ncbi.nlm.nih.gov/pubmed/20035247
• http://apps.who.int/iris/bitstream/10665/79198/1/9789241505307_eng.pdf

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