Does What I Eat Affect My Breast Milk and My Baby?

This is a guest post from Stephanie Canale, M.D., a family physician at UCLA and co-founder of Lactation Lab. Canale is a mom of two young kids and currently resides in Los Angeles, where her practice focuses on young families.

I am a family physician, educator, and mother of two that breastfed both of her children. It was only when I was back at work trying to juggle the challenges of a full time practice, being on call and worrying over my daughter not gaining enough weight despite drinking enough breast milk that I started to wonder: What’s actually in MY milk?

What’s in breast milk?

There are hundreds of proteins and hundreds of sugar molecules in breast milk and research suggests that breast milk plays an important part in helping your newborn’s immunity, development and growth. There is so much we are still learning about immune support and gut health, the protective role of breast milk in disease, obesity and more.

The idea of women wanting to know what is in their milk is not new. In 1978 a new method was published called a creamatocrit. This was a rough way of extracting how much fat and therefore calories was in a breast milk sample based on the size of the fatty layer of milk after it was spun down in a centrifuge machine. 

Each day I am asked by new moms about what supplements they should take now that they are nursing, and if what they eat affects the quality of their milk. 

Recent years have seen a growing appreciation of the importance of promoting and supporting human milk feeding for optimizing infant growth and development, including neurological development. We are learning more and more about how this is linked to maternal diet. 

Numerous studies have since been published that show that breast milk can differ significantly from mother to mother but for any given mother, the nutritional profile of milk doesn’t change much from beginning to end of a feed. Research has shown that the fat content does not vary more than roughly 5% during a feed and most physicians would agree that it is the volume of milk intake that is correlated with growth

So does it matter what nursing moms eat?

Many studies have looked at maternal status and breast milk concentration of nutrients and minerals. The most well studied information has come from research in the field of essential fatty acids. They are called “essential” since our body doesn’t make them and we need to eat them. The most well known is DHA. Similarly, intake of other omega-3 and omega-6 fatty acids are positively correlated to mother’s levels of these fatty acids.

The main dietary sources of omega-3 fatty acids are from fish. Due to mercury concerns it is recommended that pregnant and nursing moms eat no more than 2-3 servings of fish per week. It should also be noted that there are certain types of fish that should be avoided altogether when nursing (e.g., swordfish, mackerel and some tuna).

There are a few other nutrients that do vary in human milk as a result of maternal nutrition. Some of these nutrients include vitamin A, vitamin B6, and vitamin B-12. Vitamin C and calcium have also been found to positively correlate with maternal level, so it’s important to eat a varied diet. Other nutrients such as sodium, phosphorus, and zinc tend to be stable.

Vitamin A, which is important for vision, skin and skeletal growth. Vegetables that are rich in organic colors are also rich in Vitamin A. These include carrots, sweet potatoes and orange peppers for example. Other sources of Vitamin A include liver from any animal and egg yolks. Some dietary sources of Vitamin B6 include, turkey, pork, pistachio nuts, sunflower seeds, fish and dried fruits.  Vitamin B12 is found in chicken livers, clams, crab, fortified cereals, milk and yogurt. Dietary sources of Vitamin C include citrus, dark leafy greens, strawberries and melons. Dairy is a rich source of calcium in our diets but can also be found in green leafy veggies.

Iron is a bit more controversial. Although it is recommended that women get 9-10 mg of iron a day, it is unclear by how much this should increase when nursing. Newborns are born with an iron “store”, but exclusively breastfed babies will deplete this by about six months. And Vitamin D is naturally low in breast milk. This is why the American Academy of Pediatrics (AAP) recommends a universal supplement of 1 mg/kg of iron and 400 IU of Vitamin D per day for breastfed infants. It is suggested that all infants be screened for anemia (lack of iron) by 12 months of age.