Fresh Milk Consumption Reduces the Risk of Type 2 Diabetes in People with Lactose Insufficiency?!

The inclusion of cow’s milk in the diet is a common practice, but the connection between milk consumption and type 2 diabetes remains controversial. Researchers, using data from various studies, find that higher consumption of fresh milk is associated with a lower risk of type 2 diabetes in individuals with intermittent lactase non-persistence (LNP), a specific variant of the LCT gene, a single nucleotide polymorphism rs4988235, but not in those with persistent lactase.

Previous studies on the relationship between cow’s milk consumption and a reduced risk of developing type 2 diabetes have yielded mixed results, with some showing a connection and others finding little or no association. In this new study, scientists suspect that such discrepancies may be related to the genetic profiles of the study participants.

To explore this possibility, researchers examine tissue samples collected from approximately 12,000 adult Spaniards. They conduct a genome-wide association study (GWAS), searching for links between milk consumption and a reduced risk of type 2 diabetes.

The scientists evaluate the dietary intake of volunteers and find a correlation with the presence of a genetic variant that encodes lactase. Lactase is an enzyme the body uses to break down sugars in milk.

Most people synthesize lactase in childhood, and this decreases with age. Some develop lactose intolerance, also known as intermittent lactase non-persistence. The difference is traced back to a variant of the LCT gene. People with intermittent lactase non-persistence who regularly consume milk also have a 30% reduced risk of developing type 2 diabetes, according to the study. This risk reduction is not observed in individuals who regularly consume milk but do not have the genetic variant.

The genotype in the LCT locus determines lactase expression and significantly varies among different populations. Milk intake variably influences the etiology of the risk of type 2 diabetes depending on the origin. Increased milk intake alters both the abundance of gut bacteria and circulating metabolites in favor of reducing the risk of type 2 diabetes in people with lactase deficiency.

To confirm these findings, the team repeats their study using data from the UK Biobank and obtains similar results. These findings explain the diverse results found in previous tests regarding the connection between milk consumption and the risk of developing type 2 diabetes.

In additional analyses, it is discovered that among people with intermittent lactase non-persistence, higher milk intake is associated with changes in gut microbiota and circulating metabolites. Many of these metabolites are linked to the identified bacteria present in milk and partially mediate the relationship between milk consumption and type 2 diabetes.