Fermented mare’s milk, also known as koumiss, is a traditional beverage consumed in Central Asia. It typically contains alcohol, lactic acid, milk sugar, protein, fat, and it is rich in essential amino acids, trace elements, and vitamins.
In a previous study, researchers from China reported that koumiss consumption was effective in lowering lipid levels in patients with hyperlipidaemia. Hyperlipidaemia is an elevated level of blood total cholesterol and triglycerides, and is a significant risk factor for coronary heart disease.
However, the mechanism behind koumiss’s lipid-lowering effect remains unclear.
So, the same researchers conducted this follow-up work using liquid chromatography-mass spectrometry (LC-MS) and proton nuclear magnetic resonance (1H NMR) to study faecal samples of participants.
“This work found that some of the natural nutrients in koumiss were active ingredients associated with the beneficial blood lipid-lowering effect for the first time,” researchers wrote in the Journal of Functional Foods.
“Additionally, koumiss consumption not only changed the gut microbiota but also increased the level of microbiome-derived metabolites, which are associated with lipid transport and reduction,” they added.
The study utilised data collected previously, involving 13 patients aged 43 to 57 years old, recruited from the Xilin Gol hospital.
They were all diagnosed with severe hyperlipidaemia (total cholesterol > 5.82 mmol/L).
Koumiss was provided three times daily (250mL) before each meal. Faecal samples of patients were collected at day 0, 30, and 60.
By combining the results obtained by LC-MS and 1H NMR, 10 significant abundant metabolites were found to be associated with the koumiss treatment.
Seven of them were nutrients naturally found in koumiss (linoleic acid, stearic acid, sphingosine, alanine, tyrosine, α-tocotrienol, and γ-tocotrienol), and the other three were acetate, butyrate, and ursolic acid.
These metabolites significantly increased in concentration at days 30 and 60.
Most of the identified metabolites were involved in lipid metabolism and lipid transport.
Sphingosine has been found to limit intestinal cholesterol absorption by binding to cholesterol, inhibiting cholesterol transport.
Tyrosine, α-tocotrienol, and γ-tocotrienol could not interact directly with cholesterol, but could block the translation of 3-hydroxy-3-methyl-glutarylcoenzymeA (HMG-CoA) reductase, the key enzyme that produces endogenous cholesterol.
Acetate and butyrate are not naturally found in koumiss, but as short chain fatty acids produced by the intestinal microbiota through fermentation of indigestible carbohydrates, they may also facilitate lipid transport and reduction.
These findings could explain the lipid-lowering effect seen after koumiss treatment.
“This work not only provided an in-depth understanding of the biochemical mechanism of the beneficial hypolipidemic effect, but also practical information supporting the feasibility of applying diet modification in alleviating hyperlipidaemia,” researchers wrote.
Source: Journal of Functional Foods
“Untargeted fecal metabolomics revealed biochemical mechanisms of the blood lipid-lowering effect of koumiss treatment in patients with hyperlipidemia”
Authors: Bohai Li, et al.