Humans by design are predisposed to be lactose intolerant. The only reasons Westerners (mostly) lost this intolerance was due to centuries of eating cheese and having their bodies evolve to adapt to consuming it. Lactose is the number one sugar in breast milk. It’s broken down by an enzyme called lactase which is supposed to disappear in early childhood, right around the time we would naturally wean. Asian cultures are predominantly lactose intolerant because their cultures have had cuisine sans cheese and cow’s milk for millennia (think traditional Japanese, Chinese, and Korean dishes. No cheese. No cow’s milk.) Yet in Western cultures it’s occasionally encouraged to drink milk to make milk. There is no scientific evidence to back this up. You do not need to drink cow’s milk or eat dairy in large quantities to make breast milk. You do need to stay hydrated, eat quality foods, and routinely empty the breast.
Lactose is the number one sugar in breastmilk. It is the protein in cow’s milk that is difficult to digest for some babies. Human milk has human protein. It is easily digested by the stomach and absorbed in the intestines. The protein of cow’s milk is shaped different and not easily absorbed by the stomach and intestines as it’s designed to be absorbed by calves. It can sometimes make babies gassy or have poops that have bloody or mucous in them. Cow’s milk sensitivity or allergy can cause colic-like symptoms, eczema, wheezing, vomiting, diarrhea (including bloody diarrhea), constipation, hives, and/or a stuffy, itchy nose. Which can also be signs of other things. You could always try decreasing your dairy intake. Baby’s symptoms will usually begin to improve within 5-7 days of eliminating a problem food. Baby may not improve immediately, however, especially if the reaction is to a food that has been a regular part of your diet. Sometimes symptoms get worse before they begin to improve. It usually takes 2-3 weeks to see an improvement.
If baby is sensitive to dairy, it will not help to switch to lactose-free dairy products or put your baby in formula, which is cow protein based.
While culture may dictate what you can and cannot eat while breastfeeding, science does not. Most babies have no problems with anything that you eat. It’s generally recommended that you eat whatever you like, whenever you like, in the amounts that you like and continue to do this unless you notice an obvious reaction in your baby.
There is no list of “foods that every nursing person should avoid” because most of us can eat anything we want, and because the babies who are sensitive to certain foods are each unique – what bothers one may not bother another.
Babies’ guts are also constantly developing. So what bothers them as a newborn may not bother them the closer they get to a year.
Unless there are known food allergies in your family history or your baby is having severe reactions to what you think you may be eating, there’s no need to restrict what you eat. Remember: fussiness and gas is normal for a young baby, and is not usually related to foods you eat. If your baby is sensitive to something you are eating, you will most likely notice other symptoms in addition to fussiness, such as EXCESSIVE spitting up or vomiting, colic, rash or persistent congestion, crying inconsolably for long periods, or sleep little and wake suddenly with obvious discomfort. Other signs of a true food allergy may include: rash, hives, eczema, sore bottom, dry skin; wheezing or asthma; congestion or cold-like symptoms; red, itchy eyes; ear infections; irritability, fussiness, colic; intestinal upsets, vomiting, constipation and/or diarrhea, or green stools with mucus or blood. Fussiness that is not accompanied by these other symptoms and calms with more frequent nursing is probably not food-related.
Lactose is the number one carb/sugar in human milk. We wouldn’t survive as a species if babies were lactose intolerant. Human milk actually has 50% more lactose than cow’s milk! Our bodies produce a protein called lactose that breaks down lactose in the gut. Lactase is supposed to disappear after baby is weaned- usually by seven years of age. Yes, babies are supposed to be breastfeed until between 2.5 to 7 years of age. Human babies are supposed to drink only human milk and our bodies are designed to digest it efficiently and effectively. When this protein disappears, the body has a hard time digesting lactose. In reality up to 70% of adults are lactose intolerant as adults because this protein is supposed to disappear. We’re not meant to drink milk after childhood. But this shouldn’t happen until after baby is weaned- as a toddler or preschooler. The reason babies can have indigestion and upset from milk is from bovine protein either that mom is eating (those excessive cheese lovers know what I’m talking about) or from introducing artificial baby milk (aka formula that is cow’s milk based).
The proteins in milk can be divided into two categories: caseins and whey proteins (remember Little Miss Moffett on her tuffet eating her curds and whey? Curds are like the globs in cottage cheese and the whey is the watery substance). Human milk contains these in a ratio of 40:60 casein to whey; while in cow’s milk the ratio is 80:20 respectively. The amount of total protein in cow’s milk is more than double that of human milk to help baby cows double in size very quickly after baby. Cow’s milk contains considerably more casein than human milk to achieve that growth. Casein can be difficult to digest, in fact it is used as the primary ingredient of some glues! Artificial baby milks have to be formulated or altered to contain more whey than casein, to try to replicate the ratio of whey to casein to be as similar to that of human milk as it can to be better digested. But it is still a forgoing protein that the body wasn’t designed to digest.
Now there are truly some babies who have difficulties with digestion, however congenital lactose intolerance is very, very rare. It would be seen immediately after birth with very severe symptoms and should be diagnosed by a pediatrician as soon as possible. A small percentage of breastfeeding mothers notice an obvious difference in their baby’s behavior and/or health when mom eats certain foods. As previously stated, cow’s milk products are the most common problem foods and the only foods conclusively linked by research to fussiness/gassiness in babies because of the protein found in cows milk. Food sensitivities in breastfed babies are not nearly as common as many breastfeeding mothers have been led to think.
There are some really well written articles if you feel your baby has a protein intolerance. For more information, check out the following resources:
The Comparative Composition of Human Milk and of Cow’s Milk. http://www.jbc.org/content/16/2/147.full.pdf
A Comparison Between Human Milk and Cow’s Milk. https://www.viva.org.uk/white-lies/comparison-between-human-milk-and-cows-milk