Periodic Reporting for period 1 - ExMilk (Exercised breastmilk: a kick-start for childhood obesity prevention)
Reporting period: 2023-03-01 to 2025-08-31
Childhood obesity is reaching alarming proportions in many countries and poses an urgent challenge to healthcare systems. It affects a child’s immediate health and quality of life, and children with obesity are five times more likely to remain obese as adults compared with those without childhood obesity. Preventing childhood obesity is not just a medical concern, as it represents the largest contributor to the overall healthcare costs. Mothers’ pre-pregnancy body mass index (BMI) is a strong risk factor for childhood obesity, accounting for over 20% of childhood obesity cases, indicating a strong mother-to-child transmission. While genetics play a role, environmental factors during pregnancy and early life are also important. The period from conception to age two—“the first 1000 days”—is the most critical for developing obesity-related disorders. Data from human cohorts indicate that faster weight gain in the first 3 months of life is associated with a higher body fat percentage and a greater degree of abdominal obesity in childhood and later in life.
Breastfeeding is a recognized protective factor against obesity, offering nutritional and immunological advantages. Breastfed infants have a lower risk of becoming overweight than formula-fed ones. The ExMilk project is based on the premise that breastmilk is nutritionally optimal, even for infants of women with overweight or obesity. However, recent evidence shows that breastmilk composition differs between mothers with high and low BMI. ExMilk aims to improve breastmilk composition in women with overweight or obesity.
Maternal obesity is associated with changes in breastmilk components linked to childhood obesity risk, suggesting certain milk molecules mediate obesity transmission. The interaction between maternal lifestyle, breastmilk composition, and infant health is an emerging research field, with known influences from smoking, BMI, gestational diabetes, and diet. Yet, there is no experimental evidence that lifestyle-induced changes in breastmilk affect infant obesity risk. Exercise, a key behavioral factor influencing metabolic health, remains largely unexplored in this context. The ExMilk project will determine how exercise during lactation affects breastmilk composition and, consequently, infant obesity risk.
This interdisciplinary project investigates both acute and long-term exercise effects on a wide range of breastmilk components in women with overweight/obesity. By linking breastmilk data to comprehensive data for the infants, we aim to identify mechanisms through which maternal exercise influences infant obesity risk. To reach our goals, we will perform gold-standard randomised trials and analyse biological samples from mothers and infants on several analytical platforms. Our interdisciplinary expertise will enable us to break new ground in understanding how exercise during lactation modifies infant obesity risk.
Breastfeeding is a recognized protective factor against obesity, offering nutritional and immunological advantages. Breastfed infants have a lower risk of becoming overweight than formula-fed ones. The ExMilk project is based on the premise that breastmilk is nutritionally optimal, even for infants of women with overweight or obesity. However, recent evidence shows that breastmilk composition differs between mothers with high and low BMI. ExMilk aims to improve breastmilk composition in women with overweight or obesity.
Maternal obesity is associated with changes in breastmilk components linked to childhood obesity risk, suggesting certain milk molecules mediate obesity transmission. The interaction between maternal lifestyle, breastmilk composition, and infant health is an emerging research field, with known influences from smoking, BMI, gestational diabetes, and diet. Yet, there is no experimental evidence that lifestyle-induced changes in breastmilk affect infant obesity risk. Exercise, a key behavioral factor influencing metabolic health, remains largely unexplored in this context. The ExMilk project will determine how exercise during lactation affects breastmilk composition and, consequently, infant obesity risk.
This interdisciplinary project investigates both acute and long-term exercise effects on a wide range of breastmilk components in women with overweight/obesity. By linking breastmilk data to comprehensive data for the infants, we aim to identify mechanisms through which maternal exercise influences infant obesity risk. To reach our goals, we will perform gold-standard randomised trials and analyse biological samples from mothers and infants on several analytical platforms. Our interdisciplinary expertise will enable us to break new ground in understanding how exercise during lactation modifies infant obesity risk.
The first two years of the project period have mainly been spent recruiting participants for our studies and collecting data. We have expanded the activities in the project to also include analyses of the human milk samples that we collected in a pilot study before the start of the ExMilk project, as well as a separate cross-sectional study.
The participants in our studies complete the exercise protocols as intended, with very good adherence. We collect milk samples at multiple time points in the studies. In the randomised, controlled trial that we are running, we collect samples at baseline, and after four and eight weeks. In parallel, we collect comprehensive data on maternal health outcomes and data and biological sampling from the infants. The randomised controlled trial will determine whether regular exercise impacts human milk composition. We have also included a follow-up of the mothers when the baby is 9 months old to investigate long-term effects of the exercise intervention on maternal health outcomes. We have included 62 of the planned 74 (approximately) participants in the randomised controlled trial and have only three who have dropped out.
To investigate the acute effect of exercise on milk composition, we have collected repeated samples from participants in a randomised cross-over trial in which the participants completed two different exercise protocols. We have included 23 participants who have completed all training sessions and milk sampling per protocol. We plan to include two additional participants in this study before we start analysing the milk samples.
The data collection in both studies above is somewhat delayed. We have therefore analysed some milk compounds in the milk collected in our pilot study (insulin and two selected human milk oligosaccharides). We found no major impact of exercise on these compounds.
In the cross-sectional study, we are investigating the relationship between maternal cardiorespiratory fitness and milk composition. The recruitment of participants and data collection is ongoing in this study, and we have included 87 of the planned 100 participants.
We have worked on developing the methodology for isolation of extracellular vesicles in human milk and tried two different commercially available kits. A PhD student also spent time in a laboratory specialised in extracellular vesicles in Amsterdam to try to find the best option for this. This work is still ongoing. Our next step is to sequence microRNA from the isolated extracellular vesicles.
We have received two additional grants that build on the ExMilk project. One of these grants is for a PhD student to work with the cross-sectional study, the other is a grant to further investigate human milk oligosaccharides in maternal serum.
The participants in our studies complete the exercise protocols as intended, with very good adherence. We collect milk samples at multiple time points in the studies. In the randomised, controlled trial that we are running, we collect samples at baseline, and after four and eight weeks. In parallel, we collect comprehensive data on maternal health outcomes and data and biological sampling from the infants. The randomised controlled trial will determine whether regular exercise impacts human milk composition. We have also included a follow-up of the mothers when the baby is 9 months old to investigate long-term effects of the exercise intervention on maternal health outcomes. We have included 62 of the planned 74 (approximately) participants in the randomised controlled trial and have only three who have dropped out.
To investigate the acute effect of exercise on milk composition, we have collected repeated samples from participants in a randomised cross-over trial in which the participants completed two different exercise protocols. We have included 23 participants who have completed all training sessions and milk sampling per protocol. We plan to include two additional participants in this study before we start analysing the milk samples.
The data collection in both studies above is somewhat delayed. We have therefore analysed some milk compounds in the milk collected in our pilot study (insulin and two selected human milk oligosaccharides). We found no major impact of exercise on these compounds.
In the cross-sectional study, we are investigating the relationship between maternal cardiorespiratory fitness and milk composition. The recruitment of participants and data collection is ongoing in this study, and we have included 87 of the planned 100 participants.
We have worked on developing the methodology for isolation of extracellular vesicles in human milk and tried two different commercially available kits. A PhD student also spent time in a laboratory specialised in extracellular vesicles in Amsterdam to try to find the best option for this. This work is still ongoing. Our next step is to sequence microRNA from the isolated extracellular vesicles.
We have received two additional grants that build on the ExMilk project. One of these grants is for a PhD student to work with the cross-sectional study, the other is a grant to further investigate human milk oligosaccharides in maternal serum.
We have discovered an increase in adiponectin, a hormone linked to good cardiometabolic health, in human milk acutely after high-intensity exercise. Our further studies will determine if this finding can also be replicated in individuals who all have a body mass index in the overweight or obese categories. We will also determine if regular exercise chronically impacts human milk concentrations of adiponectin.
Our results so far also indicate that there is a decreased insulin concentration in human milk acutely after exercise, albeit not statistically significant. Our further research will determine the impact of both acute and chronic exercise on insulin concentrations in human milk.
Our preliminary analyses of the acute effect of exercise on human milk concentrations of two selected human milk oligosaccharides determined by NMR spectroscopy showed that there was no effect of exercise on these molecules. Our further research will establish the acute and chronic effects of exercise on several human milk oligosaccharides.
Our results so far also indicate that there is a decreased insulin concentration in human milk acutely after exercise, albeit not statistically significant. Our further research will determine the impact of both acute and chronic exercise on insulin concentrations in human milk.
Our preliminary analyses of the acute effect of exercise on human milk concentrations of two selected human milk oligosaccharides determined by NMR spectroscopy showed that there was no effect of exercise on these molecules. Our further research will establish the acute and chronic effects of exercise on several human milk oligosaccharides.