Wednesday, May 19, 2010

How Breast Milk Changes

Breast milk varies from woman-to-woman, according to the mother's diet, during a feeding, throughout the day, and during the entire nursing period. Amazing, huh? It also varies depending on the baby's gestational age.

Formula doesn't change at all and it always tastes the same.

(from Jack Newman's Guide to Breastfeeding)

A mother's diet influences the concentration of various components in her milk. For example, a mother who is a vegetarian has different amounts of fatty acids (building blocks of fats) in her milk than a woman who eats meat. A woman who eats a lot of fish will also have different fatty acids. When a woman eats garlic, as another example, the milk tastes and smells different. But why would we consider that garlic is not a normal part of breastmilk, if garlic is a normal part of a mother's diet? Since it is possible that garlic helps prevent atherosclerosis and may have some immune-boosting qualities, maybe formula companies should be adding garlic to their modified cow's milk.

It is often said that these dietary additions to the milk, such as garlic, are bad for the baby. But, in fact, they are not, except in rare cases. Babies who are breastfed usually accept solid foods better than do artifically fed babies, presumably because they have been exposed to a variety of tastes throughout their breastfeeding experience. When they start eating solids, they are already used to these tastes. Formula, on the other hand, always tastes the same.

The appearance in the milk of things the mother eats can also decrease the risk of allergy in the breastfed baby. 

On the other hand, the total amount of food the mother eats does not matter as much. Even women who are eating very little seem to produce good milk, though the quantity may decrease a little. This decrease, though, is not usually significant enough to result in insufficient production. 

There are some foods or herbs that may increase or decrease the amount of milk a mother has, but there is no research to back up what may only be a myth.

Breastmilk changes during a feeding. The best-known change is in the fat content. As the baby takes milk from the breast, the concentration of fat increases. At the beginning of the feeding, the milk may contain 1 percent fat, but by the end it is 5 percent or more, and the overall average amount the baby gets is about 4 percent. We don't know why this should be, but it may serve as a sort of appetite control for the baby.

Breastmilk composition varies widely throughout the day. For example, there is more lactose in breastmilk in the late afternoon than in the early morning. The amount of fat is highest in the morning and lowest in the late afternoon. The amount of protein is lowest in the early morning and highest in the evening. We don't know why this happens or whether this benefits mother and baby. But these variations may be more significant than we know. So which milk would the formula companies copy? The milk produced at 6 am? at 6 pm? At midnight?

Throughout the entire nursing period:
It is obvious that the milk of the first 3 or 4 days - which we call colostrum - is different from the milk that comes later. Colostrum is different in color from more mature milk. It is also stickier and thicker. It is wonderful stuff, and it is too bad that the majority of breastfeeding babies in North America don't get any, or don't get much. It is loaded with many, many white blood cells. There are up to 5 million white cells in each milliliter of colostrum, and the average is 1 million. One million cells in each milliliter is 100 times more than in your blood. And it is jam-packed with antibodies. It is also a laxative, which is important for clearing out the babies intestines, reducing the level of jaundice and preparing the baby to digest breastmilk. 

After 3 or 4 days, breastmilk changes and becomes "traditional milk." The milk becomes whiter, but has a slightly golden color, indicating that there is still some colostrum mixed in. After about a week or two, the milk could be called "mature milk" and is a bluish-white color at the beginning of the feeding, and white later in the feeding.

But milk continues to change in ways that are not obvious to the eye. For example, the number of white cells in breastmilk decreases over the first few months, but even six months after the baby is born, the mother's milk will have an average of 100,000 cells in each milliliter of milk, or 10 times more than you would have in your blood. Many of the other immune factors also decrease in concentration, but some actually increase.

Lysozyme, one such immune factor that attacks the cell walls of bacteria and kills them, is present in the milk in greater concentrations after the first year than before. It should be noted that a decrease in immune factors does not mean an absence or insignificant amount. After all, formulas have NO immune factors at all (except for nucelotides, which are not really of much significance), yet when we talk about the immune factors in breastmilk decreasing, people see mto think this is a serious concern. Yet nobody worries about the virtually total absence of immune factors in formula. 

It has been shown that an exclusively breastfeeding five-month-old who is gaining weight well is not getting that much more milk than an exclusively breastfeeding one-month-old baby who is gaining weight well. He generally takes only about 10 percent to 20 percent more milk, even though he may weigh twice as much as the one-month-old. In other words, the 5 month old is getting only about 60 to 70 calories per kg per day, whereas the formula-fed baby of the same age is getting 90 to 100 calories per kg per day. Why is it that formula is needed in such large amounts, relatively speaking? The requirements of the appropriate constituents of breastmilk are somehow better and more efficiently used than the substitute constituents found in artificial baby milks. Could this be one of the reasons why studies find formula-fed babies more likely to grow up to be overweight as adults? Perhaps they have gotten used to eating large amounts of food in order to get the nutrients they need.

Anyone who says there is no value in breastmilk (unfortunately this seems to include many physicians, and even pediatricians) doesn't understand that the milk is different, but certainly hasn't changed to white-colored water. Breastmilk is still valuable from the nutritional and immunologic points of view, and, let us not forget, breastfeeding still has bonding, psychological and emotional benefits! 

Depending on gestational age:
A baby who is born prematurely has different needs from those of a baby born at term, depending on how much he is premature. Interestingly, the milk of the mother whose baby is born prematurely is different form that of the mother whose baby is born at term. A premature baby needs more protein and more sodium than a baby born at term. Well, ilk of the mother who delivers prematurely has more protein and more sodium. A premature baby is at greater risk of developing an infection. Well, milk of the mother who delivers prematurely has more white cells and antibodies. The baby born prematurely has missed out on some of the long-chained polyunsaturated fatty acids that are important to the development of his brain and vision. Well, milk of the mother who delivers prematurely has more of these fatty acids. 

Other variables:
There is evidence that if the mother offers one breast twice in a row to the baby, the milk of that breast will be different the second time than if she had offered the other breast for the second feeding. Specifically, the second feeding on the same breast will have a higher concentration of fat.

If the mother breastfeeds for the normal period of time - that is, 3 or 4 years - the milk will vary with her menstrual period. Many mothers claim the supply is down during the bleeding phase, but the components of the breast milk change also. On average, a woman who breastfeeds a baby longer than a year will get back her period about 13 or 14 months after the baby's birth. 

There is also evidence that milk is different if the mother has had several previous pregnancies than if this is her first pregnancy. 

What is missing from infant formulas?
There are no antibodies in infant formulas. No lysozyme, no epidermal growth factor, no white cells, no oligosaccharides to help white infection. No lots of things. In fact, there are dozens of components in breastmilk, all with their own functions, which are not present in infant formulas. What functions? We don't always know. Some components have multiple functions. For example, lactoferrin is probably responsible for the fact that so much of the iron in breastmilk is absorbed by the baby. But it also denies iron to bacteria, which need it to multiply, and thus decreases their rate of growth. It works together with white cells and antibodies to kill bacteria more effectively. And maybe it has more functions as well. We are only beginning to discover the wonders of breastmilk. 

Isn't breast milk amazing? I really think its quite incredible. It is exactly the right amount and right composition for your baby, at any age. It changes in flavor based upon what mom eats, unlike formula which will always taste the same. Your body which grew and nurtured your infant before she was born continues to nourish your infant after.

To people who tell you that breastmilk has no benefits after 6 months:
In the second year (12-23 months), 448 mL of breastmilk provides:
29% of energy requirements
43% of protein requirements
36% of calcium requirements
75% of vitamin A requirements
76% of folate requirements
94% of vitamin B12 requirements
60% of vitamin C requirements 


  1. Super interesting! I am a huge supporter of breastfeeding and am forever grateful for the support I got from doula to help me through the initial challenges that Soleil and I faced in the beginning. She is 14 months and we are still going strong!

  2. It is so amazing isn't it. There is some evidence that the protein also increases right after the mother eats.

    Stacy Lowery Pagan
    Expectantly Looking Forward

  3. Hello! I am interested in the composition of breastmilk if you breastfeeding a new baby and still an older toddler. Would be really interesting to know how the milk is affected and behaves by different ages nursing but cannot find anything on the subject.

  4. I'm not sure if u are interested or not but I am a exclusive pumping mommie with a oversupply. I currently have over 2,000 ounces in my deep freezer that I offer for sale to other moms in need..i can sent u a bag to see if ur satisfied, if u are then I will be happy to send u more. .i have shipped over 1000 oz to a couple different states , i ship it with dry ice in a cooler through fedex and provide tracking information. .. if u r interested I have buyer reviews and satisfied returning mommas. ..just wanted to let you know:)
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