Vetagro Journal Club, #8

It is common knowledge that human milk has several immediate and medium/long-term positive effects on the health of babies, but what about milk consumption in adulthood? Industrial milk production is often on trial, but recent findings can give us a new point of view about this wonderful food.

Milk is appreciated for its good organoleptic characteristics and is part of the diet of many people. It also contains several interesting macro- and micro-nutrients, important for human wellbeing: protein, fat, carbohydrates, calcium, vitamins, and mineral salts. Moreover, the vast majority of people can eat milk without any allergic phenomena or food intolerance. Nevertheless, milk is often substituted by vegetable-based drinks for personal life choices and ethics. These drinks are commonly called “vegetable milk”, but there are many differences between them and real milk.

To start off, there is a substantial difference in terms of nutrient composition, but mostly, the latest discovered “nutrient” in milk marks a significant difference compared to vegetable-based drinks. Milk contains microRNA (miRNA), noncoding RNA of about 18-25 nucleotides, contained in extracellular vesicles (EVs), and able to modulate the expression of several genes through post-transcriptional gene silencing. All species produce miRNA and secrete them into the milk, but the exciting feature is that more than 100 miRNA in milk are highly conserved among species.

miRNAs physiologically regulate the innate and adaptive immune activity that controls the inflammatory response of the organism. We all face inflammation in our everyday life. Even if it is the starting point to face infections, inflammation can also be a negative reaction if not correctly regulated. For this reason, milk could be a useful tool to protect us from severe diseases.

The EVs contained in the raw milk are not degraded by gastric or pancreatic digestion so that they can be absorbed by the host even though recent studies indicate that EVs can be partially destroyed by industrial ultraheat treatment (UHT). On the other hand, pasteurization or homogenization don’t reduce the number of EVs but alter their structure and content. Anyway, milk-derived miRNA can be detected in human tissues and bloodstream, even after heat treatments.

Based on all these findings, nutrimiromics was born: a new science that studies the influence of the diet on the modification of gene expression due to epigenetic processes related to miRNAs. The production and excretion of miRNA can be controlled by environmental and dietary factors. More research and experiments are mandatory to delineate the situation more accurately but in the future diet manipulation may become a therapeutic approach in modulating inflammation. If we must improve livestock sustainability and environmental impact by every means available, it is undeniable that milk is important to improve our health status and useful to have a balanced diet.

miRNA and industrial milk heat-processing. Kleinjan, et al. 2021. J. Nutr. 151(6):1416-1425. Full text here.
Bovine milk miRNAs and humans. Wang et al. 2018. J. Nutr. 148(1):153-159. Full text here.
miRNA and the immune system. Metha and Baltimore. 2016. Nat. Rev. Imm. 16:279-294. Full text here.

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