Foremilk is the skim-like milk that the baby gets at the start of the nursing session. Hindmilk is the richer and creamier milk that the baby gets at the end of the feeding. In this picture you can see the difference in a mother’s milk when pumped at the beginning and then at the end. We discuss more about foremilk and hindmilk in our book: Doulas’ Guide to Birthing Your Way.
The New York Times reported on a study by PNAS (Proceedings of the National Academy of Sciences) describes how human milk sugars protect and coat the newborn’s digestive tract. It is really fascinating. Human milk has numerous kinds of oligosaccharides. The oligosaccharides in milk are lactose-based complex sugars. Each sugar molecule has between three and ten sugars attached together.
The news is that, this complex of sugars changes during lactation. In early lactation, many of these oligosaccharides are not digestible to the infant. Instead, scientists believe they evolved in milk to attract the strain of bifidobacteria which is the most helpful to the infant’s gut. They have specially named it: bifidobacterium longum subsp. infantis. This bacteria has evolved with us to protect babies’ guts!
This bacteria is part of the infant’s early immune system. They are mapping the genome of this special bacteria now. As you can guess, it is not available in formula.
Breastmilk has many components. It is 87% water. It contains proteins, carbohydrates and fats. It has water soluble vitamins (such as B12, C, riboflavin, folate and others). It contains minerals and ions like calcium, chloride, magnesium, sodium and potassium among others. It has fat soluble vitamins like A, D, E and K. It has trace minerals such as iron, zinc, fluoride and more. It has amino acids which are the building blocks of proteins.
It also contains a large variety of living cells. Many of the living cells give babies immunities. Although there are a greater concentration of these cells in colostrum, mature milk also gives babies a great deal of living cells which protect against bacteria, viruses and molds.
Human milk is rich in fatty acids and especially long-chain poly-unsaturated fatty acids. These fatty acids are critical to helping babies develop retinal (eye) and neural (brain) tissues. (Marie Biancuzzo’s Breastfeeding the Newborn)
Mother’s milk changes during the day and the season, the same way your diet changes. It changes in fat content and flavor and gives the baby more types of tastes than formula does. Breastmilk gives your baby variety and formula always tastes the same.
The components of human breast milk differ greatly from cow’s milk. Cow’s milk is made for calves and human milk is made for human babies. Most artificial infant formula is based on cow’s milk.
The major nutrients in breastmilk are carbohydrates, lipids (fats) and proteins. Human milk contains two types of protiens, curds and whey. Cow’s milk has them too, but in a very different ratio. Human milk is 60% whey and 40% curds. Cow’s milk is 20% whey and 80% curds. The large percentage of curds in cow’s milk makes iron difficult for babies to absorb.
Artificially fed babies have to digest significantly more protein than breastfed babies. Human milk has lower levels of protein, calcium, sodium, potassium and other ions. (From Marie Biancuzzo’s Breastfeeding the Newborn). This means that breastfed babies’ kidneys work half as hard as artifcially fed babies’ kidneys. Premature babies have kidneys that get stressed much faster than a full-term baby’s does. For a premature baby who is formula fed, that can mean very serious health problems.