Variations in composition of breast milk between different ethnic groups and the association with maternal nutrition and offspring health

Breast milk naturally provides the infant with the best possible nutrition and
it plays an important role in priming the immune system, colonizing the
gastrointestinal (GI) tract and protecting against diseases later in life. The
composition of breast milk largely varies between women as it changed according
to several factors, such as time of the day and time postpartum. The role of
maternal diet has been studied several times before, however due to limitations
in study design and execution, no conclusions can currently be made on the role
of maternal diet and several breast milk components. This information will be
of importance in the development of nutritional guidelines aiming to optimize
nutrition for both, mothers and infants. Next to that, some women cannot
breastfeed their children until the recommended age of 6 month. Infant formula
is an important alternative to breast milk for those mothers who cannot
breastfeed their children. Therefore, it is of special importance for infant
formulas to mimic the natural composition of breast milk as closely as possible
and thus to understand the determinants of breast milk composition.

This study aims to investigate the effect of maternal diet and ethnicity on
breast milk composition.

In addition, we look at possible differences in the intestinal flora and the
health of the infant based on the composition of the breast milk and other
characteristics of the mother.

In this cross-sectional study, data will be collected during 5 study days
spread over a 4 week period.
During the first study day, participants will complete a short questionnaire on
general characteristics and one food record.
On the second study day, mothers will collect the first breast milk sample and
fill in the second food record throughout the day, ending with the second
breast milk sample collection the following day. In addition, participants will
also be asked to collect a 24-hr urine sample, to assess urinary recovery
markers.
On the 3rd study day, mothers will collect 20 ml of pooled breast milk during
their morning feed (between 6:00 and 8:00). Mothers will also collect faecal
samples of their infants, the sample collection can be planned in on a day of
choice of the mothers, but should be completed by the time the researcher is
doing the home visit and sample collection (study day 3). The stool sample will
be labelled and stored in the household freezer. All other biological samples
will be stored in the household fridge and picked up by a research staff on the
3rd study day. During the home visit on study day 3, the researcher will also
measure the weight and height of both, mothers and infants.
On the 4th study day, mothers will complete brief questionnaires on general
infant characteristics and infant GI health, and complete the third food
record.
The 5th study day will be a weekend day, during which mothers will fill in a
questionnaire assessing infant development, and complete the fourth and final
food record. Together the four food records will enable to estimate the
habitual dietary intake of the mothers.

No risk is expected for participants participation in this study. The
measurements will be home-based and the different questionnaires and sampling
procedures were spread out over several study days, to lower the burden on the
participants. While there are no direct benefits for the mothers, they still
get the opportunity to learn more about their infant and the impact nutrition
can have on breast milk composition and ultimately infant health.