Even people with lactose intolerance have benefited from milk
On average, 65% of the world's adult population is lactose intolerant. This carbohydrate, found in dairy products, is not absorbed through the wall of the small intestine and is normally broken down by the enzyme lactase. But in its absence, lactose passes into the large intestine. There, bacteria take over: they metabolize lactose, releasing a mixture of gases (carbon dioxide and methane), which leads to various intestinal disorders.
It turned out that the consumption of milk with lactase deficiency can have a positive effect: undigested lactose, which gets to the bacteria, leads to an increase in their diversity, which helps to reduce the risk of type 2 diabetes. This is the conclusion of scientists who studied the genotype, gut microbiome and blood levels of metabolites in 12,000 participants in the Hispanic Community Health Study over an average follow-up period of six years. Their results were published today in the journal Nature Metabolism.
Researchers assessed dietary milk intake using two dietary recalls (participants were asked to recall all the foods and beverages they consumed in 24 hours) and a food cravings questionnaire. As a result, an increase in milk consumption per one cup serving was associated with a reduction in the risk of developing type 2 diabetes by about 30%, and only in participants with a non-functioning lactase gene. The link between milk consumption, lactase genotype and risk of developing type 2 diabetes was then confirmed in 167,000 people in the UK Biobank.
When analyzing the participants' microbiome, the study authors found a distinct change in the number of intestinal bacterial species, particularly bifidobacteria. Also, lactase-deficient milk consumers showed changes in circulating blood profiles (e.g., increased levels of indolepropionate, a beneficial gut metabolite). These changes were associated with certain bacteria associated with milk.
The new work significantly changes the view of lactose intolerance per se. For years, it was often concluded that people with this intolerance should not consume milk. There have even been lactose-free product lines. Now, however, it turns out that even for those with intolerance, it makes sense to consume milk.
Type 2 diabetes is one of the most widespread diseases of our time, and its frequency in modern conditions is only increasing. In total, more than half a billion earthlings suffer from this disease. It is believed that at least 1.5 million people a year die from diabetes itself, and another 2.2 million annual deaths are closely related to it.