The World Health Organization (WHO) recommends that babies be exclusively breastfed for the first 6 months of life , since breastfeeding plays an important role in public health. Nevertheless, many mothers struggle with initiating and maintaining breastfeeding. Although this can be ascribed to a variety of limiting factors, many mothers (40 to 60 percent) stop breastfeeding due to a perception of low milk supply. Evidence is increasing that low milk supply is certainly not a perception only, with an estimated incidence of actual lactation insufficiency of 10 to 15 percent. The underlying causes of actual lactation insufficiency are currently poorly understood.
To better understand the causes of these lactation problems, objective and noninvasive methods to measure human milk intake and composition are necessary. This is why researchers from the University of Twente in The Netherlands are studying the optical properties of human milk. The light scattering behavior of milk contains a wealth of information about the milk composition, in particular fat content. Fat forms the main source of energy in human milk, and changes in fat concentration are predictive for adequate milk production after birth.
Two of their studies have been recently published in Biophotonics Discovery . In the first study , they collaborated with colleagues from the University of Amsterdam to investigate the refractive indices of the light scattering particles in human milk. An important finding is that the refractive indices of fat particles in human milk are significantly different from those in cow’s milk, which advocates for the use of human milk, and the relevant specific values, for further research.
In the second study , they therefore used the measured human milk refractive indices from the first study to predict the light scattering behavior of the milk. They further analyzed the influence of other sample specific properties from their earlier work, including fat concentration, milk serum refractive index and milk particle sizes. The main finding from the second study is that the light scattering behavior of human milk is not only influenced by its fat concentration, but also by the sample specific size distribution of the fat particles in the milk. Variations in particle refractive index between human milk samples and other sample-specific properties had a negligible effect on variations in light scattering behavior between milk samples.
The combined findings from both studies in Biophotonics Discovery aid the future development of light scattering based methods for human milk analysis. Compared to other methods for milk analysis, these light scattering methods can be made compact, fast, and preserve the milk for infant consumption afterwards. These benefits open possibilities for the inline monitoring of changes in milk composition during a single breastfeed, which will provide a powerful tool for more in-depth research into lactation insufficiency.
For details, see the original Gold Open Access articles:
“ Refractive index of milk fat globules and extracellular vesicles in human milk ,” by J. R. de Wolf et al., Biophoton. Discovery 3(1), 012104 (2026), doi: 10.1117/1.BIOS.3.1.012104
“ Influence of sample-specific properties on light scattering by human milk ,” by W. Verveld et al., Biophoton. Discovery 3(1), 012105 (2026), doi: 10.1117/1.BIOS.3.1.012105
These articles feature in the BIOS Special Section “ Maternal, Reproductive, and Neonatal Health ”.
Biophotonics Discovery
Not applicable
Influence of sample-specific properties on light scattering by human milk
9-Mar-2026