I am a family physician, educator, and mother of two that breastfed both of her children. It was only when I was at work trying to juggle the challenges of a full-time practice, being on call and worry over my daughter not gaining enough weight despite drinking enough volume of breast milk that I started to ask myself what is in MY milk.
Breast Milk Research Then & Now
The idea of women wanting to know about their breast milk health and what is in it 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.
Breastfeeding is not for everyone and not everyone is able to do so, but for those who can and choose to, there are certain vitamins and minerals that are correlated with maternal status. The benefits of breast milk extend beyond nutrition to include emotional and psychological bonding between mother and child. There are hundreds of proteins and hundreds of sugar molecules in breast milk that plays an important part in immunity, development, and growth. There is so much we are still leaving out about immune support and gut health, the protective role of breast milk in atopic diseases, obesity, and some have even suggested intelligence.
Do Supplements and Nutrition Affect your Breast Milk Health?
Every 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 in fact, term milk within the same mother does not vary as much as one thought. It should be noted that many used to differentiate between foremilk and hindmilk noting the increased fat content at the end of a feed. The methods that have been studied have variability and research has shown that the fat content with the same mother does not vary more than roughly 5% from the beginning to the end of a feed. Most physicians would agree it is the volume of milk intake that is correlated with growth. Breast milk contains fat and does not change significantly from the initial feed to the end of the feed.
It has also been suggested that mothers should increase their diets to 500 calories a day more than baseline while nursing. But could it be true that some need more?
Fatty Acids are Essential for Breast Milk Health
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, other omega-3’s and omega-6 fatty acids are positively correlated to mother’s levels.
A study in South Dakota taught moms about how their diet affects their milk and in fact their made appropriate changes and with dietary changes were able to increase their levels just weeks later.
The main dietary sources of omega-3 fatty acids are from fish. Due to mercury concerns it is recommended to eat no more than 2-3 meals 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).
The Impact & Importance of Vitamins A, B, & C
It should be noted that not every vitamin and mineral will change over time. Minerals such as sodium, phosphorus, and zinc tend to be consistent across women. Some studies have found a link between maternal calcium and iron and the levels in their milk while others have not. It is difficult to fully understand the relationship as the many studies carried out to date have involved small sample sizes and varies in the methods used to measure these elements.
However, there are a few 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.
Vitamin A which is important for vision, skin and skeletal growth, is related to maternal level. Vegetables that are rich in organic colors are also rich in Vitamin A. These include carrots, sweet potatoes and orange peppers for example. Dietary sources of vitamin A include liver from any animal, egg yolks, sweet potatoes, carrots, and squash. Some dietary sources of vitamin B6 include turkey, pork, pistachio nuts, sunflower seeds, fish, and dried fruits. B12 is rich in chicken livers, clams, crab, fortified cereals, some 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 and Vitamin D Levels in Breast Milk
Iron has been controversial. Some studies have linked it to increased levels in maternal diet while others have not. Although it is recommended that a lactating woman take 9-10 mg of iron a day and it is unclear by how much this should increase when nursing. Many studies have varied with the time at which iron levels have been measured in breast milk and have often failed to control for the amount of blood loss and changes in maternal iron stores after delivery.
The AAP (American Academy of Pediatrics) recommended a universal supplement of 1 mg/kg of iron and 400 IU of vitamin D per day for breastfed infants. Many others and doctors I know don’t necessarily carry out this recommendation as the iron supplements can be difficult for a newborn to digest and many mothers believe can increase gas and fussiness. It is suggested that all infants be screened for anemia by 12 months of age. Vitamin D is universally low across milk of all species.