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Research on donkey milk · Study 17
Lysozyme from donkey milk & the gut barrier
In 2018, Jiang et al. isolated the enzyme lysozyme from donkey milk and examined in a mouse model what changes in the intestinal wall, inflammatory markers and gut flora during a colitis induced in the laboratory.
Why this study is interesting
One enzyme, three perspectives
Lysozyme is an enzyme that can cleave sugar chains in the cell walls of certain bacteria. It occurs naturally in donkey milk – according to the literature in considerably higher amounts than in cow's milk.
The researchers at China Agricultural University wanted to know what changes in the gut of mice when they receive isolated lysozyme from donkey milk and a colitis is then induced in the laboratory. They looked simultaneously at the intestinal wall, at inflammatory markers and at the gut flora.
In addition, they determined the spatial structure of the enzyme – to understand how it binds its target molecules.
What exactly was tested?
Study logic
From the enzyme to the measurement
Lysozyme was isolated from donkey milk and its structure determined by X-ray crystallography.
Some of the mice received the lysozyme orally. Comparison groups did not receive it.
DSS (dextran sulfate sodium) was used to induce colitis – a common laboratory model.
Weight, tissue, barrier proteins, inflammatory markers and the gut flora were examined.
Interactive · A look into the intestinal wall
Three states, five measuring points
Switch between the healthy reference, the inflammation model and the lysozyme group. Tap the numbers to see what was measured at each point.
Schematic illustration, not a microscopy image from the study. It shows the direction of the reported changes, not their size. "With lysozyme" means: compared with mice with DSS but without lysozyme.
Key findings
What the researchers report
Signs of disease
Less weight loss, less damage to the colon and less inflammation of the mucosa.
Occludin & ZO-1
Two proteins that tightly connect intestinal cells and seal the barrier.
Claudin-2
A cell-junction protein that tends to make the barrier more permeable.
TNF-α & IL-13
Messenger substances of the immune system that rise during inflammatory processes.
Myeloperoxidase
An enzyme from infiltrating immune cells that is regarded as an inflammatory marker.
Gut flora
Greater diversity and altered composition of the gut bacteria.
All figures compared with mice with DSS inflammation without lysozyme. Group sizes, doses and exact measured values are not given in the freely available abstract – we therefore only show the direction of the results.
A look into the molecule
The X-ray structure showed a lysozyme with a conserved active site – the cleft in which the enzyme works. In some binding sites it differs from other lysozymes. The researchers suspect that it therefore binds its target molecules somewhat differently.
Possible relationships
A chain with question marks
Cleaves sugar chains in bacterial cell walls.
Composition changes.
Cell junctions are measured.
Messenger substances and immune cells.
Important for interpretation: The findings are consistent with each other but do not prove a sequence. An altered gut flora can be the cause, consequence or concomitant of weaker inflammation. The chain is a hypothesis that further studies must test.
Critical assessment
Interesting – but don't over-interpret
What the study shows
What it does not show
Research question for DON DONKEY’S®
How much active lysozyme is in our milk?
Literature values for lysozyme in donkey milk vary depending on herd, stage of lactation and measurement method. There are no measurements of our own yet for our frozen raw milk. The question arising from the study: how much lysozyme is present, how active is it after freezing and storage – and what remains after simulated digestion?
DON DONKEY’S®
DON DONKEY’S® donkey milk
100 % donkey milk · raw milk, frozen
Discover our donkey milk as a food. Our research pages show which questions science is investigating about donkey milk – and where the limits of the available evidence lie.
100 ml bottle / 100ml · Unit price: €249,00 / 1 l · incl. VAT, plus shipping
Original publication
Donkey milk lysozyme ameliorates dextran sulfate sodium-induced colitis by improving intestinal barrier function and gut microbiota composition
Jiang L., Lv J., Liu J., Hao X., Ren F., Guo H.
Journal of Functional Foods · 2018 · 48:144–152
DOI: 10.1016/j.jff.2018.07.005
The publication describes preclinical research with isolated lysozyme in a mouse model. The results do not allow any statement of efficacy in humans or any product-related statement for DON DONKEY’S®. If you have bowel complaints, please consult a doctor.