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.
Fact of the day: Human milk has one of the highest levels of lactose among mammals: 7%. Lactose accounts for almost all the carbs in breastmilk and provides 40-50% of the energy in the milk. Lactase is the enzyme naturally produced in the body to convert lactose into simple sugar. This enzyme is prevalent in our bodies at birth but it’s production lessens after age 3. Up to 70% of the world’s adult population has a lactase deficiency, which is indicative of the body maturing and no longer needing human milk as the primary source of nutrition. It is rare for children under 3 to have lactase deficiency, reflecting the biologically normal age for weaning.