Breast milk: how quickly DAIRY protein clears

It has been well documented that allergens to pass from the maternal diet into breast milk, although the amounts are highly variable.

It has been demonstrated time and time again that after exclusion of dairy (and usually soy as well due to their similarity in proteins) from the maternal diet atopic manifestations against cow’s milk proteins in previously sensitized breastfed infants disappear (1).

Thus means that it is well established that symptoms of cow's milk allergy resolve when dairy protein (and often soy protein as well) is removed from the mother's diet.

Intact food allergens or peptides (fragments of the proetin in cow's milk) in breast milk that have been documented include:

• egg protein (ovalbumin),

• wheat protein (gliadin)

• peanut protein

• and of course cow's milk proteins (a variety of different whey and caesin proteins).

The presence of dietary peptides in breast milk provides indirect evidence that fragments of food proteins can survive the gastrointestinal digestion, pass into the bloodstream, and distribute to peripheral organs (1).

This means that it has been shown by the presence of protein and protein fragments (called peptides) in breast milk shows that proteins can be passed into breast milk without being broken down into its smallest units: amino acids.

In summary, cow's milk protein is broken down in the mother's digestive gut to smaller fragments and abosrbed into her system.

The cow's milk protein fragments is then used by her breasts to make human milk protein.

If the human milk protein in her breast milk contains enough of the building blocks of cow’s milk protein, it can cause dairy allergy in the baby if the baby is sensitive to dairy.

The same process can happen with soy protein.

How long does it take to get improvements when first going dairy and soy free?

Impacts of dairy (and soy) exclusion from the maternal diet actually has a variable time frame in terms of bub's improvements when dairy and soy is first removed from the mother's diet.

Some babies respond very quickly with some very significant imporvements with common ones being: decreases in bowel motion frequency, reduction of mucous, resolution of or reduction in blood in the nappies, reduced reflux, reduced screaming and irritability, reduced wakenings in the night and resolution or reducton in eczema/rashes.

Some take seemingly forever- requiring 3-4 weeks to start seeing any noticable improvements. It is not unusual to take a while in this phase of the dairy/soy journey.

Or there is a combination, some quick significant improvements followed by some slower improvements over time.

At the 3-4 week mark, not withstanding potential slip ups, maximal improvement (including healing) should be achieved from dairy exclusion.

It can take a while, because of the healing process. A baby being triggerred for a while with protein from dairy (and likely soy) in the diet will get an irritated gut, and so removing the allergens may get some initial imporvement but then we need the gut tpo recover and settle down.

When Dairy Protein is First Detected in Breast Milk

There is a complete lack of reliable data, with lots of variability in methods of detection in the different studies, and poor quality trials. Many studies have focused on whole intact proteins, but it has been shown the protein fragments called peptides need to also be measured as they are also found in breast milk from the maternal diet (1).

Individual variation very likely exists between mothers and may include:

• individual digestion capacity

• other foods consumed at the same time and their structure

• altered intestinal permeability of the mother

• transitory leakage at the level of the mammary epithelium.

Appearance of cow's milk protein in breast milk after maternal consumption.

A very small study (10 breast milk samples from a single mother, reference 1) showed that the dairy protein was first detected in breast milk one hour after dairy food was consumed by the mother.

This reflects what seems to happen, with a related increase in baby's symptoms 1-4 hours after the dairy food is consumed.

Of course, what dairy food is consumed and dose and the baby's individual sensitivity will mean that there are significant differences between babies with CMPI (Cow's Milk Protein Intolerance).

Peak concentration of dairy protein in breast milk after maternal consumption.

Peak concentration refers to the highest concnatration of the dairy protein in the breast milk after consuming the dairy protein in the diet.

Peak concentration measurements for dairy protein have been reported from 1 hour- 24 hours and as long as 7 days.

The same very small study discussed above (2019) that tested ONE breast feeding mother given a cup of milk to consume, with milk samples taken at regular intervals up to 6 hours post consumption in 2019 indicated that the peak concntration of cow's milk protein after consumption was 2 hours (1).

Looking at the graph provided for this one person (please note, there will be so many individual differences to this scenario for different breast feeding mothers), the peak at 2 hours is not much more than when first detected ion the breast milk at one hour.

Anecdotal: 7 day peak reaction does not seem to play out in practice.

Clearance of dairy protein in breast milk after maternal consumption

This refers to the time it takes for the dairy protein to clear from the breast milk and is of great interest as it eans you may be able to pump and dump (pump the breast milk after dairy exposure via the maternal diet and not use it, relying on previous frozen breast milk for this period)

In the small study referenced above: study of one mother (1), the rapid appearance of the dairy protein in the breast milk after one hour of consumption was subsequently found to be cleared after 6 hours.

Again, this is the results from ONE BREAST FEEDING MOTHER so if applying this data to your situation, be aware that it may not be true for you.

Two proteins measured in one breast feeding mother, time is hours after a cup of cow's milk is consumed.

β-Lg (Beta- lactoglobulin), which is major cow's milk protein has been measured in other studies and the results points to slower as well as faster clearance trends, with some women being categorized as 'rapid' metabolizers so it cleared more quickly and some women 'slower' metabolizers so a slower clearing from the breast milk (2).

With huge variation, it is very possible that comparable amounts of dairy protein in the breast milk will result in:

• different levels of dairy protien in the breast milk

• be cleared from the breast milk in different time frames

• elicit different symptoms (and severity) in individual babies.

With all these variables, your own baby is your study. You should be able to see how quickly your baby with diagnosed dairy protein intolerance or allergy reacts and how ong it seems to take to recover, after a slip up.

Going dairy free versus challenging with dairy

The time it takes for a baby to recover after initially going dairy (and soy) free is not indicatative of how long a baby will react after a slip up.

These are very defferent scenarios.

Initially going dairy/soy free: in addition to clearing dairy from the milk, there is the additional time required for gut healing which can account for the often lengthy period to see maximal improvements post the initial exclusion from the maternal diet.

Dairy trials: trialing with dairy via breast milk is not superimposed on top of a gut under duress, but a functioning gut that has not only healed but has further developed since the dairy/soy protein exclusion. Hence there is no legthy recovery but a natural improved response more related to how long it takes for protein to clear from the breast milk.

This makes dairy trials via breast milk an excellent way of determing dairy tolerance and the level of restriction required in the maternal diet.

Knowing Your Baby

In my experience, it becomes very evident over time that parents become well versed in their own baby's unique pattern of peak reaction time, types of symptoms and length of time to recover.

Most babies with dairy slip ups or trials will recover relatively quickly, and cannot be compared to the original length of time it takes to recover after eliminating dairy/soy from the maternal diet.

Dairy milk protein is usually excreted from the breast milk in a matter of days so remains a very useful way of determining level of required dairy protein restriction in the mother's diet, and guaging if your baby's dairy protein intolerance is improving.

REFERENCES

1. Picariello, Gianluca, et al. "Excretion of dietary cow’s milk derived peptides into breast milk." Frontiers in Nutrition 6 (2019): 25.

2. Kosmeri C, Rallis D, Kostara M, Siomou E, Tsabouri S. Characteristics of Exogenous Allergen in Breast Milk and Their Impact on Oral Tolerance Induction. Front Pediatr. 2022 Mar 4;10:830718. doi: 10.3389/fped.2022.830718. Erratum in: Front Pediatr. 2022 Apr 14;10:898795. PMID: 35311039; PMCID: PMC8931296.